Egor A Bersenev

Evgeniia A Nikitina

Erfan Dashtimoghadam

Sergei S Sheiko

Dimitri A Ivanov

Bottlebrush Elastomers with Crystallizable Side Chains: Monitoring Configuration of Polymer Backbones in the Amorphous Regions during Crystallization

ABSTRACT: Brush-like elastomers with crystallizable side chains hold promise for biomedical applications requiring the presence of two distinct mechanical states below and above body temperature: hard and super-soft. The hard semicrystalline state facilitates piercing of the body whereupon the material softens to match the mechanics of surrounding soft tissue. To understand the transition between the two states, the crystallization process was studied with synchrotron X-ray scattering for a series of brush elastomers with poly(ε-caprolactone) side chains bearing from 7 to 13 repeat units. The so-called bottlebrush correlation peak was used to monitor configuration of bottlebrush backbones in the amorphous regions during the crystallization process. In the course of crystallization, the backbones are expelled into the interlamellar amorphous gaps, which is accompanied by their conformational changes and leads to partitioning to unconfined (melt) and confined (semi-crystalline) (conformational) states. The crystallization process starts by consumption of the unconfined macromolecules by the growing crystals followed by reconfiguration of macromolecules within the already grown spherulites.

Bottlebrush polymers are unique systems where the counteraction between the backbone elasticity and steric repulsion of densely grafted side chains imposes strong effect on molecular packing and mechanical properties. Such materials hold promise for applications as photonic crystals [START_REF] Sunday | Confinement and Processing Can Alter the Morphology and Periodicity of Bottlebrush Block Copolymers in Thin Films[END_REF][START_REF] Guo | Structure Memory Photonic Crystals Prepared by Hierarchical Self-Assembly of Semicrystalline Bottlebrush Block Copolymers[END_REF][START_REF] Zhao | Angular-Independent Photonic Pigments via the Controlled Micellization of Amphiphilic Bottlebrush Block Copolymers[END_REF] , materials for organic electronics [START_REF] Obhi | Self-Assembly of Poly(3-Hexylthiophene) Bottlebrush Polymers into End-On-End Linear Fiber Morphologies[END_REF] and biomedicine [START_REF] Johnson | Drug-Loaded, Bivalent-Bottle-Brush Polymers by Graft-through ROMP[END_REF] . In particular, the architectural disentanglement of macromolecules allows for the design of ultrasoft and hyper-elastic materials that can replicate the deformation response of soft tissues [START_REF] Dobrynin | Chameleon-like Elastomers with Molecularly Encoded Strain-Adaptive Stiffening and Coloration[END_REF][START_REF] Keith | Bottlebrush Bridge between Soft Gels and Firm Tissues[END_REF][START_REF] Keith | Independently Tuning Elastomer Softness and Firmness by Incorporating Side Chain Mixtures into Bottlebrush Network Strands[END_REF] . Introduction of crystallizable side chains [START_REF] Yu-Su | Crystallization of molecular brushes with block copolymer side chains[END_REF] affords thermoplastic materials with a sharp transition from a hard state to super-soft state, where the elastic modulus drops by unprecedented six orders of magnitude from ~1 GPa to ~1 kPa, unmatched by conventional thermoplastics. [START_REF] Zhang | Tissue-Adaptive Materials with Independently Regulated Modulus and Transition Temperature[END_REF] Furthermore, controlling the side chain length allows tuning the melting temperature, which empowers as the design of tissue-adaptive microneedles that soften upon insertion to the body to mechanically blend with the surrounding tissue. [START_REF] Zhang | Tissue-Adaptive Materials with Independently Regulated Modulus and Transition Temperature[END_REF] Recent studies of crystallizable bottlebrushes polymers have focused on crystallization kinetics and semi-crystalline morphology. [START_REF] López-Barrón | Isothermal Crystallization Kinetics of α-Olefin Molecular Bottlebrushes[END_REF][START_REF] Sun | Configurationally Constrained Crystallization of Brush Polymers with Poly(Ethylene Oxide) Side Chains[END_REF] The so-called bottlebrush correlation peak was observed in X-ray scattering curves at 𝑞 1 * and interpreted as an average distance between the neighboring bottlebrush backbones. [START_REF] López-Barrón | Syndiotactic α-Olefin Molecular Bottlebrushes: Crystallization, Melting, and Hierarchical Microstructure[END_REF] In contrast to linear polymers, where interchain correlation vanishes upon melting, the bottlebrush peak remains distinctly visible in the melt state due to side chain repulsion, which both separates the backbones and generates strong electron density contrast at the backbones. In a melt of bottlebrushes with short aliphatic side chains (up to C18), the peak position, 𝑞 1 * , was shown to linearly shift for with the side-chain length, 𝑛 𝑠𝑐 . [START_REF] López-Barrón | Highly Entangled α-Olefin Molecular Bottlebrushes: Melt Structure, Linear Rheology, and Interchain Friction Mechanism[END_REF] However, for longer side chains (up to 𝑛 𝑠𝑐 =156 for chains of poly(dimethyl siloxane)), the correlation becomes non-linear and can be approximated by a scaling law with a power of 0.41. [START_REF] Keith | Independently Tuning Elastomer Softness and Firmness by Incorporating Side Chain Mixtures into Bottlebrush Network Strands[END_REF] Upon crystallization, the appearance of the bottlebrush peak becomes strongly affected, [START_REF] López-Barrón | Isothermal Crystallization Kinetics of α-Olefin Molecular Bottlebrushes[END_REF] suggesting changes in the conformation and packing of the bottlebrush backbones in the semicrystalline state. During side-chain crystallization, the backbones are rejected into the interlamellar amorphous regions. The variation of the peak position and intensity can serve as a marker for configuration of the bottlebrush backbones in the amorphous regions. [START_REF] Sarapas | Bottlebrush Polymers in the Melt and Polyelectrolytes in Solution Share Common Structural Features[END_REF] Such information is complementary to the conventional assessment of crystallinity and semicrystalline micro-structure by wide-and small-angle X-ray scattering (WAXS and SAXS), as it adds a new dimension to the analysis of the crystallization process. This provides a unique opportunity for characterization of microstructure of the confined amorphous regions that are typically inaccessible in linear chain systems. As mentioned above, linear polymers usually do not generate a distinct single-chain structure factor, which prohibits using X-ray scattering for monitoring molecular conformation in the amorphous phase of semi-crystalline polymers.

So far, the state of confined interlamellar amorphous chains and its evolution during polymer crystallization process has been successfully acquired from their relaxation behavior. For example, for semirigid-chain semicrystalline polymers, it was shown that confining polymer chains in the interlamellar amorphous regions might result in significant increase of the glass transition temperature. [START_REF] Ivanov | The crystallization of poly(aryl-ether-ether-ketone) (PEEK). Interdependence between the evolution of amorphous and crystalline regions during isothermal cold-crystallization[END_REF][START_REF] Ivanov | The crystallization of poly(aryl-ether-ether-ketone) (PEEK). Reorganization processes during gradual reheating of cold-crystallized samples[END_REF][START_REF] Ivanov | Vitrification/Devitrification Phenomena during Isothermal and Nonisothermal Crystallization of Semi-Crystalline Polymers and Blends : Poly(aryl-ether-etherketone) (PEEK) and PEEK/ Poly(ether-imide)[END_REF] Monitoring the relaxation behavior of such polymers during crystallization allowed observing two distinct relaxation processes, where the signal of the initial bulk amorphous phase was gradually decreasing at the expense of a new relaxation pertinent to the growing fraction of the amorphous regions confined in the inter-crystalline gaps. The modified state of the confined amorphous chains was further elucidated with transmission electron microscopy. 19 In the present work, we use the bottlebrush X-ray correlation peak to extract information about the configuration of bottlebrush backbones in a semi-crystalline state (or during side-chain crystallization). This is implemented by monitoring variation of the 𝑞 1 * -peak intensity and position during crystallization process. Simultaneously, real-time characterization of the semicrystalline microstructure (thickness of the crystalline and amorphous regions, and bulk crystallinity) using the classical SAXS and WAXS data analysis. A series of chemically crosslinked bottlebrushes with systematically varied degree of polymerization (DP) of poly(εcaprolactone) (PCL) side chains was synthesized (Table 1). The resulting crosslink density corresponds to approximately one crosslink per 50 monomers of the main backbone. The details of the synthesis, the chemical structure and parameters of the molecular weight distribution are provided in Supplementary Material.

Table 1. Molecular and thermal characteristics of the synthesized bottlebrush networks Sample name nsc [START_REF] Sunday | Confinement and Processing Can Alter the Morphology and Periodicity of Bottlebrush Block Copolymers in Thin Films[END_REF] d1, [START_REF] Guo | Structure Memory Photonic Crystals Prepared by Hierarchical Self-Assembly of Semicrystalline Bottlebrush Block Copolymers[END_REF] nm Tm, [START_REF] Zhao | Angular-Independent Photonic Pigments via the Controlled Micellization of Amphiphilic Bottlebrush Block Copolymers[END_REF] °C Tc, [START_REF] Zhao | Angular-Independent Photonic Pigments via the Controlled Micellization of Amphiphilic Bottlebrush Block Copolymers[END_REF] °C Tm, [START_REF] Obhi | Self-Assembly of Poly(3-Hexylthiophene) Bottlebrush Polymers into End-On-End Linear Fiber Morphologies[END_REF] °C Tc, [START_REF] Obhi | Self-Assembly of Poly(3-Hexylthiophene) Bottlebrush Polymers into End-On-End Linear Fiber Morphologies[END_REF] [START_REF] Sunday | Confinement and Processing Can Alter the Morphology and Periodicity of Bottlebrush Block Copolymers in Thin Films[END_REF] DP of the poly(ε-caprolactone) side chains; [START_REF] Guo | Structure Memory Photonic Crystals Prepared by Hierarchical Self-Assembly of Semicrystalline Bottlebrush Block Copolymers[END_REF] d-spacing of the 𝑞 1 * -peak of the bottlebrush melt; melting and crystallization temperatures of the bottlebrush networks [START_REF] Zhao | Angular-Independent Photonic Pigments via the Controlled Micellization of Amphiphilic Bottlebrush Block Copolymers[END_REF] and the corresponding macromonomer used for the synthesis [START_REF] Obhi | Self-Assembly of Poly(3-Hexylthiophene) Bottlebrush Polymers into End-On-End Linear Fiber Morphologies[END_REF] .

Basic thermodynamic and structural features of the synthesized bottlebrush networks were characterized by Differential Scanning Calorimetry (DSC) and SAXS (Table 1). The bottlebrush architecture imposes constraints on chain mobility during crystallization process, which explains the decrease of both melting temperature (Tm) and crystallinity compared to linear oligomers of the same length as well as the corresponding macromonomers used in the synthesis. Thus, the difference in Tm between bottlebrush elastomers and the corresponding macromonomers can reach 27 K (cf. Table 1 and Fig. S2).

Figure 1 displays 1D SAXS curves of the sample with 𝑛 𝑠𝑐 = 13 measured in the melt at 80°С and in the semicrystalline state at 20°С. These curves exemplify two characteristic features of all studied materials: (i) bottlebrush correlation peak, d1, in both amorphous and semicrystalline states and (ii) Bragg peak (Lp) originated from the interference between the crystals.

By examining the bottlebrush correlation peak with more scrutiny, we can see that the peak shape and position are different for the amorphous and semicrystalline states. This difference becomes apparent in the corresponding background-corrected curves (Fig. 1, inset). Upon completion of crystallization, the bottlebrush peak notably weakens, broadens, and shifts to higher q-values. Therefore, the incorporation of side chains into growing crystals causes significant modification of the bottlebrush configuration by expelling the backbones to the neighboring inter-crystalline amorphous layers. The envelope of a bottlebrush polymer is likely to lose its initial symmetrical shape due to disordering of the backbones arrangement and squeezing them closer to each other. Figure 1. Top: SAXS patterns of sample PCL_13 recorded in the melt at 80 °C and after 30 min of isothermal crystallization at 20 °C. Dashed lines represent the background intensity used to correct the data. Inset shows the background-corrected regions of the curves with the bottlebrush peak shifted vertically for clarity. Bottom: 1D SAXS curves of the bottlebrush melts at 80 °C with subtracted background showing the d1 correlation peak. The PCL_13 curve is given in black, PCL_11 in purple, PCL_9 in green, and PCL_7 in orange. Inset shows the scaling of the d1spacing with the side-chain length (nsc).

For the bottlebrush networks, the position of the bottlebrush peak in the melt correlates with their side-chain length (Fig. 1B). The dependence of d1 on nsc can be approximated by a scaling law with an exponent of 0.42±0.03, which is in good agreement with the theoretical prediction mentioned in the introductinon. [START_REF] Keith | Independently Tuning Elastomer Softness and Firmness by Incorporating Side Chain Mixtures into Bottlebrush Network Strands[END_REF] This allows extending the observed scaling behavior to a broader family of bottlebrushes with side chains of very different chemical structure, e.g., ranging from poly(dimethylsiloxane) to aliphatic polyesters. The results of a typical isothermal melt crystallization experiment are shown in Figure 2. In the measurement, the sample was shortly brought to the molten state at 80 °C after which it was cooled down to the temperature of crystallization at a rate of 80 °C/min. The SAXS/WAXS frames were acquired every 6s with exposure of 6 ms. Selected time-resolved SAXS and WAXS curves show that the fast stage of crystallization completes within several minutes. The progressive increase of the Lp peak intensity occurs simultaneously with enhancement of the crystalline peaks' intensity in WAXS. In parallel, the changes occur in the q-region of the bottlebrush correlation peak as discussed earlier. To provide a quantitative description of the crystallization process based on the evolution of the bottlebrush correlation peak, the intensity in this q-region was approximated as a linear combination of the initial and final intensities as follows: 𝐼(𝑞, 𝑡) = 𝛼(𝑡)𝐼 𝑚𝑒𝑙𝑡 (𝑞, 𝑡) + 𝛽(𝑡)𝐼 𝑠𝑐 (𝑞, 𝑡) + 𝐼 𝑏𝑐𝑘𝑔𝑟 (𝑞, 𝑡)

where 𝐼 𝑚𝑒𝑙𝑡 , 𝐼 𝑠𝑐 and 𝐼 𝑏𝑐𝑘𝑔𝑟 stand for the intensity of the quiescent melt before the onset of crystallization, intensity of the final semicrystalline state of the sample and the background intensity. The functions 𝛼(𝑡) and 𝛽(𝑡) reflect the fractions of the initial (i.e., bulk amorphous) and final (i.e., confined semicrystalline) phases contained in the sample at time t. The 𝐼 𝑚𝑒𝑙𝑡 and 𝐼 𝑠𝑐 were obtained by averaging ca. 10-20 frames and were subsequently approximated by an appropriate analytical function. The example of decomposition of the intermediate state recorded during crystallization of sample 13 at 20°C is given in Figure 3 for the elapsed time of 220 s. At this stage of the crystallization process, the bottlebrush peak exhibits a pronounced composite character being approximately 0.4:0.6 mixture of the initial and final states. Experimental points are shown in dots, solid lines correspond to fits of the data with Eq(1). Inset: intermediate state of the bottlebrush correlation peak at t = 220 s (light grey dots). Light red solid line denotes the bottlebrush correlation peak in the melt with α= 0.41, blue solid line is intercrystalline confined state with β= 0.59.

The results of deconvolution of the SAXS intensity on the initial and final states (eq 1) are given in Figure 4A. The computed 𝛼(𝑡) and 𝛽(𝑡) vary between 1 and 0 as expected. The progress in the crystallization process is marked by a decay of 𝛼(𝑡) with simultaneous increase of 𝛽(𝑡). Moreover, the sum of the two functions stay close to unity at all times meaning that the intensity of the bottlebrush peak can be indeed well approximated by a linear combination of the initial and final states, i.e. the 𝐼 𝑚𝑒𝑙𝑡 and 𝐼 𝑠𝑐 functions. As expected, the 𝛼(𝑡) and 𝛽(𝑡) level out when all the initial amorphous phase is consumed. In the considered case this occurs after ca. 300s of crystallization, which corresponds to the stage of spherulites' impingement when all the amorphous phase in the sample becomes confined. It is, therefore, clear that the bottlebrush peak provides a means to monitor the consumption of the bulk amorphous phase and its gradual replacement by the amorphous regions confined in-between the crystals. This information is somehow similar to what has been achieved in the past by monitoring the intensity of the α-relaxation peak during crystallization. [START_REF] Ivanov | The crystallization of poly(aryl-ether-ether-ketone) (PEEK). Interdependence between the evolution of amorphous and crystalline regions during isothermal cold-crystallization[END_REF] Here, the bottlebrush peak can also serve as a indicator allowing to discriminate and quantify the bulk and confined amorphous regions based on the configuration of the polymer chain. However, the information contained in the acquired data has broader implications discussed below. Figure 4B displays the computed 𝛽(𝑡) together with the simultaneously measured SAXS invariant and WAXS crystallinity index. The three curves follow similar paths during the rapid stage of crystallization (stage I), where the bulk amorphous phase is consumed. However, upon levelling out of the 𝛽(𝑡) function, the SAXS invariant continues to increase for about 300 s more (stage II), suggesting that secondary crystallization processes take place within the grown spherulites. At an even later stage (stage III), when the invariant does not change anymore, the WAXS crystallinity index continues showing a slight increase. This development can be understood by analyzing the crystal thickness from the 1D correlation functions computed from SAXS data. The inset in Fig. 4B shows that crystal thickness exhibits a monotonic increase, which continues even after 900 s of the isothermal crystallization process. Such slow crystal thickening in PCL was previously observed based on real-time imaging with Atomic Force Microscopy. [START_REF] Basire | Evolution of the lamellar structure during crystallization of a semicrystalline-amorphous polymer blend: time-resolved hot-stage SPM study[END_REF] Later, some evidence for crystal perfectioning The described findings allow us to conclude that the crystallization process in the PCL-based bottlebrush elastomers is multistage. At the first stage, the side chains of the bottlebrush elastomers get progressively involved in the crystal growth process whereas the backbones are being rejected in the inter-crystalline amorphous gaps. This is schematically illustrated in Figure 5 showing possible packing of the bottlebrush backbones inside the interlamellar amorphous regions. The full consumption of the unconfined material occurs after about 450 s, which corresponds to the end of stage I. From the morphological point of view, this corresponds to impingement of growing banded spherulites of the bottlebrush as shown in the figure inserts. At stage II (up to 780s), the entire structure formation processes occur inside the already grown spherulites. Here, the SAXS invariant still exhibits a noticeable increase (cf. Fig. 4, bottom), which is likely due to some postcrystallization processes. Some of these processes continue beyond ~780s (stage III), where the SAXS invariant levels out but the WAXS crystallinity index is still increasing (i.e., the third stage of crystallization). Importantly, the SAXS crystal thickness Lc displays a logarithmic increase throughout the whole process, which is consistent with our earlier observations on blends of linear PCL and poly(vinyl chloride). [START_REF] Basire | Evolution of the lamellar structure during crystallization of a semicrystalline-amorphous polymer blend: time-resolved hot-stage SPM study[END_REF] The computed Lc-values correspond to the crystalline stems of the length varying from ca. 4.5 to 5.2 repeat units, which slightly more than one third of the total side-chain length. Therefore, it is logical to assume that the ends of the side chains enter lamellar crystals leaving the parts of the side chains located closer to the main backbone in the amorphous region.

To understand the universality of the described crystallization behavior, it is instructive to compare the crystallization process occurring in the studied bottlebrushes with the longest and shortest side chains, i.e. for PCL samples with 𝑛 𝑠𝑐 = 7 and 13. Figure S3 shows selected SAXS and WAXS curves corresponding to isothermal melt crystallization of PCL_7 at -10 °C. Application of the same strategy for the analysis of the bottlebrush peak shows much similarity in the crystallization behavior of the two samples. Indeed, the 𝛼(𝑡) and 𝛽(𝑡) functions add up to 1 as is the case of the PCL (𝑛 𝑠𝑐 = 13) crystallization (cf. Fig. S5, left), which shows that the bottlebrush peak provides indeed the means of quantifying the unperturbed bulk and confined intercrystalline fraction of the bottlebrushes. Also, the crystallization process is multistage and is characterized by post-crystallization in the interior of the spherulites with a long-term thickening of the crystals. The difference in the behavior of the two samples is in the kinetics, which can be accounted for by the different degree of supercooling and in crystal thickness. Since the remaining amorphous part of the bottlebrush molecules become smaller, the position of the bottlebrush correlation peak shifts to larger q-values. Also, perturbation of the bottlebrush packing causes the bottlebrush peak to become broader. The interlamellar amorphous regions can in principle host a couple of layers of the bottlebrush backbones as shown in the figure. The details of packing and orientation of the bottlebrush backbones are still to be explored. It is noteworthy that during melting the evolution of the bottlebrush correlation peak shows an opposite trend: the bottlebrush peak typical of the semicrystalline state vanishes and the one characteristic of the bulk polymer melt reappears as the melting process advances (cf. Fig. S7).

The impact of soft confinement of the PCL side chains imposed by the bottlebrush backbones can be analyzed in comparison with hard confinement, which can be generated for example by infiltration of linear PCL into the well-studied nanoporous anodic aluminum oxide (AAO) templates. [START_REF] Shi | Reexamining the Crystallization of Poly(εcaprolactone) and Isotactic Polypropylene under Hard Confinement: Nucleation and Orientation[END_REF][START_REF] Safari | Effect of Nanoconfinement on the Isodimorphic Crystallization of Poly(butylene succinate-rancaprolactone) Random Copolymers[END_REF] The walls of the AAO pores well isolate each polymer domain and can cause a dramatic depression in the PCL crystallization temperature Tc. By contrast, crystallization of the bottlebrush networks studied in the present work does not show such an effect on Tc (cf. Fig. 2S). Therefore, contrary to the hard confinement the mechanism of crystal nucleation in the bottlebrushes is likely to be unchanged with respect to the bulk linear polymer. In our case, the resulting semicrystalline morphology of banded spherulites is typical of polymer crystallization at small and moderate undercoolings and testifies the fact that crystallization proceeds via breakout growth. In this process, the bottlebrush phase-separated morphology becomes disrupted by the growing lamellar crystals which "pass through" the interfaces delimited by the backbones and eventually trap the backbones in the interlamellar amorphous gaps. In conclusion, the synchrotron time-and temperature-resolved SAXS and WAXS techniques with an aid of optical microscopy unveil the hierarchical organization of the bottlebrush elastomer with crystallizable side chains. Moreover, the presence of a unique bottlebrush correlation peak provides a unique probe to observe configuration of chains in the amorphous regions. Using this peak as an amorphous phase marker makes it possible to follow the consumption of the unconfined material during crystallization and address the state of the bottlebrushes in the interlamellar amorphous gaps. However, a more detailed evaluation of the structure of such crystallizable bottlebrushes is required, including nano X-ray beam diffraction experiments on the banded spherulites grown from these materials.

ASSOCIATED CONTENT

Supporting Information. Materials and synthesis, NMR characterization of the bottlebrush polymers, molecular and structural parameters of the studied bottlebrush copolymers, SAXS data treatment and analysis. The Supporting Information is available free of charge via the Internet at http://pubs.acs.org."

Figure 2 .

 2 Figure 2. Selected 1D-reduced SAXS (top) and WAXS (bottom) patterns of sample PCL_13 recorded during isothermal melt crystallization at 20 °C. The color code bar represents the elapsed time of crystallization.

Figure 3 .

 3 Figure 3. Variation of the bottlebrush peak during crystallization of sample PCL_13 at 20°C. The color code is the same as in figure 2.Experimental points are shown in dots, solid lines correspond to fits of the data with Eq(1). Inset: intermediate state of the bottlebrush correlation peak at t = 220 s (light grey dots). Light red solid line denotes the bottlebrush correlation peak in the melt with α= 0.41, blue solid line is intercrystalline confined state with β= 0.59.

  from X-ray scattering data by Strobl and coworkers.[START_REF] Kohn | Continuous Changes in the Inner Order of the Crystalline Lamellae during Isothermal Crystallization of Poly(-Caprolactone)[END_REF]

Figure 4 .

 4 Figure 4. A: Evolution of 𝛼(𝑡) and 𝛽(𝑡) for isothermal crystallization of PCL (𝑛 𝑠𝑐 = 13) at 20°C. Optical micrographs in crossed polars show growth and impingement of banded spherulites resulting from crystallization. B: Comparative behavior of SAXS invariant (black symbols) and WAXS crystallinity index (green symbols). Inset shows the evolution of crystal thickness computed from SAXS data using 1D correlation function analysis.

Figure 5 .

 5 Figure 5. Schematics of the backbone and side chain arrangement in the molten and semicrystalline states.

ACKNOWLEDGMENT E.A.B, E.A.N and D.A.I. acknowledge financial support from the Ministry of Science and Higher Education of the Russian Federation within State Contract 075-15-2022-1117 from June 30, 2022. E.D., and S.S.S. acknowledge funding from the National Science Foundation (DMR 1921835 and DMR 2004048). The authors acknowledge perfect technical support from the personnel of the ID02 beamline of the ESRF in Grenoble (France).

Funding Sources

E.A.B, E.A.N and D.A.I. acknowledge financial support from the Ministry of Science and Higher Education of the Russian Federation within State Contract 075-15-2022-1117 from June 30, 2022. D.Z., E.D., and S.S.S. acknowledge funding from the National Science Foundation (DMR 1921835 and DMR 2004048).

AUTHOR INFORMATION

Corresponding Author *Email: dimitri.ivanov@uha.fr.

Author Contributions § These authors contributed equally to this manuscript and have shared co-first authorship. E.D., and S.S.S. synthesized and characterized bottlebrush elastomers; E.A.B., and E.A.N. performed synchrotron and laboratory X-ray experiments and data analysis; D.A.I. supervised the X-ray data analysis and conceived the idea of using the bottlebrush peak to monitor chain configuration in a crystallization process; D.A.I. was primary writer of the manuscript. The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript. SYNOPSIS TOC (Word Style "SN_Synopsis_TOC").

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Waltraud Paul
email: wpaul@ehess.fr

SVCs in disguise: the so-called "directional verb compounds" in Mandarin Chinese *

The so-called directional verb compounds (cf. Li & Thompson 1981: 58) or directional constructions in Mandarin Chinese, 'V1displacement V2direction lái (come)/ qù (go)', e.g. bān chū lái 'transport exit come' = 'bring out (towards the speaker)' are not compounds, but genuine object sharing serial verb constructions in Collins' (1997) sense. The different positions of the shared internal argument are derived by raising one, two or three verbs to v, each verb adjoining to v as closely as possible (tucking in à la Richards 1997), thus maintaining the relative order between the verbs (cf. Collins 2002). This analysis automatically predicts that the internal argument must follow the verb (sequence) bearing the aspectual suffix, a correlation left unexplained in previous works.

* This article has benefited from discussions with Liu Chang, Lu Yaqiao and Thomas Hun-tak Lee, as well as from comments by an anonymous reviewer and the editor of this volume, Andrew Simpson. 1 Given that for the position of the object and of aspect suffixes, adjacent verbs behave as a compound in syntax, they are linked by a hyphen.

Introduction

Practically every surface string with more than one verb in Chinese has been considered a serial verb construction (SVC), because in Chinese linguistics the term SVC is typically not used to refer to a unique construction with an associated set of predictable properties, but instead serves as a cover term for a myriad of separate constructions with completely different structures, such as control structures, sentences with postverbal purposive clauses or preverbal adjunct clauses, with sentential subjects etc. (cf. Paul 2008 and references therein). Strangely enough, the socalled directional verb compounds (cf. Li & Thompson 1981: 58), 'V1displacement V2direction lái (come)/ qù (go)', have not been termed SVCs. This is probably due to their misanalysis as compounds, i.e. as words, despite the well-known fact that aspect suffixes and objects can occur at different positions "inside" the alleged compound (e.g. bān-chū-lái ), as shown in (1b) -(1c):

(1) a.

Tā cóng fángjiān lǐ bān -chū-lái -le [yī bǎ yǐzi]. 1 3SG from room in transport-exit-come -PERF 1 CL chair b.

Tā cóng fángjiān lǐ bān -chū -le [yī bǎ yǐzi] lái. 3SG from room in transport-exit-PERF 1 CL chair come c.

Tā cóng fángjiān lǐ bān -le [yī bǎ yǐzi] chū-lái. 3SG from room in transport-PERF 1 CL chair exit-come 'She brought out a chair from the room.' (Liu/Pan/Gu 2001: 572) In fact, these "compounds" turn out to be genuine SVCs in the strict sense as defined by [START_REF] Collins | Argument sharing in serial verb constructions[END_REF], representing a single event with one aspect/tense marker and sharing of the internal argument. (For first proposals in this direction, cf. [START_REF] Ernst | On verb subcategorization in Chinese[END_REF][START_REF] Law | A note on the serial verb construction in Chinese[END_REF][START_REF] Paul | The "serial verb construction[END_REF], 2008). This analysis allows us to derive the different positions for the shared internal argument yī bǎ yǐzi 'a chair' observed in (1a-c) by raising of the verb(s) to v, starting from the internal argument sharing SVC 'V1 object DP pro V2 lái '. In (1c), only V1 raises to v (as is standard), whereas in (1a-b) V1 and V2 or all 3 verbs move to v, each verb adjoining to v as closely as possible (tucking in à la [START_REF] Richards | What moves where when in which language?[END_REF], thus maintaining the relative order between the verbs (cf. [START_REF] Collins | Multiple verb movement in Hoan[END_REF]. This also correctly predicts that the object must follow the verb (sequence) bearing the aspectual suffix, for it is the verb (sequence) adjoined to v that further raises to Asp° (if projected).

The present article provides ample evidence for such an analysis. It is organized as follows. Section 2 establishes the basis for the present study. It presents an overview of the phenomena subsumed under the traditional label "directional verb compound", discusses the properties of the verb classes involved in their formation and determines the subset of structures that indeed involve SVCs and are to be further examined. Section 3 spells out the details of my analysis of SVCs, based on [START_REF] Collins | Multiple verb movement in Hoan[END_REF] and [START_REF] Richards | What moves where when in which language?[END_REF]. This new analysis avoids major shortcomings encountered by earlier proposals and can derive the correct order of verbs after raising as well as the different positions available for the object. Section 4 turns to aktionsart differences and takes as its starting point the general observation in the literature (cf. a.o. Zhu Dexi (1982), [START_REF] Kimura | On two functions of the directional complements lái and qù in Mandarin[END_REF], [START_REF] Yuehua | Qūxiàng bŭyŭ de yŭfă yìyì [The grammatical meaning of directional complement[END_REF]) that the order where all verbs are adjacent 'V1-V2-lái O' gives rise to a telic predicate, while the non-adjacent orders 'V1-V2 O lái' and 'V1 O V2-lái' are atelic. Section 5 addresses the issue of definite DP objects in SVCs. Their distribution is subject to constraints, in contrast to indefinite objects of the format 'Num CL N' which are allowed in all three position theoretically available in a complex SVC. Again, this is a well-known fact and goes back at least to Zhu Dexi (1982: §9.4), but has so far not received a satisfying account. Section 6 concludes the article and outlines some of the remaining open research questions.

Clearing the ground

Before presenting the relevant generalizations about "directional verb compounds" known from the vast literature in Chinese on this subject, a brief caveat about terminology is called for. In the following, the term SVC exclusively refers to the internal argument sharing SVC in the sense of [START_REF] Collins | Argument sharing in serial verb constructions[END_REF], not to the cover term for any multi-verb surface string as currently (mis-)applied in the literature. "Directional verb compounds" enclosed in quotation marks is used when I want to refer to the traditional term and the constructions subsumed here, which turn out not to be homogeneous, either. Note that the Chinese literature uses the term "verbs with a directional complement (qūxiàng bǔyǔ)", which, however, has the same coverage as the English term "directional verb compound".

Three verb classes

Taking the "directional verb compounds" consisting of three verbs 'V1 V2 lái/qù ('come/go')' (which will be shown to involve genuine SVCs) as a starting point (cf. (1a-c) above), three verb classes are to be distinguished.

The first, V1, is an open class which can largely be described as involving displacement, i.e. change in location of the patient in the case of transitive verbs such as bān 'transport', sòng 'send', rēng 'throw', dài 'carry' etc., and movement of the agent in the case of intransitive verbs such as pǎo 'run ', fēi 'fly' etc. 2 V2 is the closed class of so-called "directional verbs" (with six to eight members depending on the author):3 shàng 'ascend ', xià 'descend', jìn 'enter', chū 'exit', huí 'return', guò 'cross', qǐ 'rise, start', kāi 'open'. The first six all select locative nouns as object when used in isolation (e.g. xià lóu 'descend staircase', huí jiā 'return home'). Both qǐ 'rise, start'and kāi are more complex cases. Besides the unaccusative verb qǐ 'rise, start' as in Qǐ fēng le. 'rise wind SFP' = 'Wind came up.', there is also the unergative verb qǐ 'rise, get up' as in Tā hái méi qǐ '3SG still NEG rise' = 'He still hasn't gotten up (from bed).'. Similarly, in addition to the transitive verb kāi 'open' (kāi mén 'open the door'), we also have the unaccusative verb kāi 'bloom', as in Jīntiān kāi-le xǔduō méiguīhuā 'today bloom-PERF many rose' = 'Today there bloomed many roses.'. Given this and other complications, inter alia specific constraints on the object position (cf. Lu Jianming 2002: 15), examples with kāi 'open, bloom' and qǐ 'rise' as V2 will not be included.

V3 is the closed class consisting of the two deictic verbs laí 'come' and qù 'go', which as in other languages indicate direction towards or away from the speaker, respectively. As will become clear in the remainder of the article (cf. section 5 below), two cases need to be distinguished: (i) the unaccusative verbs laí 'come' and qù 'go (away)' with a unique internal argument as in (2); (ii) the transitive verbs laí 'come (to)' and qù 'go (to)', with a locative noun as object as in (3). (For a detailed study of the existential construction as a diagnostics for unaccusative verbs, cf. Paul/Lu/Lee 2020; also cf. Basciano 2010: 140ff, § 4.2):

(2) a.

Jīntiān lái -le sān ge kèrén. today come-PERF 3 CL guests 'There have come three guests today.' b.

Zuótiān yǐjing qù-le sān ge rén. yesterday already go-PERF 3 CL person 'Yesterday, there already left three persons.'

(3) Tāmen lái -le /qù-le Běijīng. 3PL come-PERF/go-PERF Beijing 'They have come/gone to Beijing.' 2.2. SVCs: complex and simple: Vdisplacement (Vdirectional) lái/qù 'come/go' (4) -( 6) below provide some more examples of SVCs with three verbs, henceforth called "complex" SVCs to distinguish them from "simple" SVCs of the form 'Vdisplacement DP lái/qù ', illustrated in (7-9) 155)) 3SG transport-cross-go-PERF 1 CL chair direction to or away from the speakers, translated as a 'verb + particle' combination into English: shàng-lái 'ascend-come'= 'come up (towards the speaker)', xià-qù 'go down (away from the speaker)' etc.

b.

Tā bān -guò -le [yī bǎ yǐzi] qù. 3SG transport-cross-PERF 1 CL chair go c.

Tā bān -le [yī bǎ yǐzi] guò -qù. 3SG transport -PERF 1 CL chair cross-go 'He carried over a chair (away from the speaker).' (6) a.

Tā ná -chū -lái-le [yī běn cídiǎn]. 3SG take-exit-come-PERF 1 CL dictionary b.

Tā ná -chū-le [yī běn cídiǎn] lái. 3SG take-exit-PERF 1 CL dictionary come c.

Tā ná -le [yī běn cídiǎn] chū-lái. 3SG take-PERF 1 CL dictionary exit-come 'She took out a dictionary.'

The "simple" SVCs consist of only two verbs, i.e. a displacement verb plus the deictic verbs lái 'come' or qù 'go'. (Cf. Lu Jianming 2002: 8;(18-29) In both complex and simple SVCs, it is the leftmost, i.e. highest verb (sequence) that carries the aspect marker, here the perfective aspect suffix -le. It is also this very same verb (sequence) plus aspect that is followed by the object DP. This results in three object positions for complex SVCs and two for simple SVCs.

The fact that the position to the right of the verb (sequence) cum aspect suffix coincides with the object position has so far not been accounted for, but straightforwardly follows from the analysis proposed here, for only the verb(s) raised to v can further raise to Asp° and thus occupy a position above, hence precede the (overt) object in SpecVP. While the detailed analysis is presented in section 3 below, the somewhat simplified tree structure in (10) below already conveys the basic idea for the case where only the displacement verb bān 'transport, move' has undergone v-to-Asp° raising: This differs from the three positions in principle available for a patient DP in complex SVCs (cf. section 2.1 above). (17a-c), for example, neatly contrasts with the complex SVC bān-jìn lái 'transport-enter-come', where the object DP has the patient role: These facts are well-known from the literature, but have so far not been accounted for. Note, though, that Chao (1968: 477) makes the crucial observation that a locative noun object is unacceptable in the bǎ construction, in contrast to non-locative objects such as yǐzi 'chair' in (20): The contrast between ( 21) and ( 22) and the single position for locative noun objects follow directly from my proposal, where ( 22), but not (21), is analysed as an SVC, the object bearing a patient role. The difference between the two constructions is confirmed by the fact that the agent of lái/qù 'come/go' in ( 16) -( 19) is the (matrix) subject, not the object. I therefore suggest the same analysis as for ( 11) -( 13) above, i.e. an adjunct clause preceding the main verbs lái 'come' or qù 'go' (cf. ( 14) above). For semantic reasons, only locative objects are allowed in such an adjunct clause:

(
(23) Tāi [adj.cl. proi zǒu -jìn jiàoshì] lái /qù. 3SG walk-enter classroom come/go 'He walked into the classroom (towards/away from the speaker).' As a result, cases of "directional verb compounds" with locative objects are excluded from further examination in the remainder of the article, because they do not involve SVCs. 2.3.3 "Directional verb compounds" without lái 'come' or qù 'go' Finally, there are also "directional verb compounds" of the form 'Vdisplacement + Vdirectional', i.e. without lái 'come' or qù 'go'. Depending on the semantics of the verbs involved, they select either a patient as object (cf. ( 24) -( 26)) or a location (cf. ( 27) -( 28)). In both cases, the object must follow the entire sequence, the order 'Vdisplacement [DP] Vdirectional' being excluded. They are therefore analysed as compounds, on a par with compounds such [V° bà-shǒu] 'stop-hand' = 'give up', [V° bāng-zhù] 'assist-help' = 'assist, help', [V° xué-huì]'learn-know' = 'acquire, master' etc., which in syntax behave like simple verbs and are followed by their object. Not being SVCs, [Vdisplacement -Vdirectional] (29b) shows that the clause serving as adjunct of the matrix verb lái 'come' in (29a) is a wellformed independent sentence with a [Vdispl + Vdir] compound. In other words, sentences with a [Vdispl + Vdir] compound predicate selecting a locative noun object are all acceptable as adjunct clauses for lái 'come' and qù 'go' as matrix verbs.

Interim summary

The phenomena subsumed under the traditional label "directional verb compounds" are not homogeneous, but involve different constructions.

First, there is the case just discussed which indeed is to be analysed as a compound verb, consisting of a displacement verb plus a directional verb, where the object (a patient or a location) must follow the compound: [V° Vdispl. -Vdir.] DP.

Second, there are sentences where the matrix verb lái 'come' or qù 'go' is modified by an adjunct clause, whose predicate is either a simple directional verb or a compound verb 'Vdispl + Vdir', both selecting a locative noun object: DPi [adj.cl. proi [V° (Vdispl.) Vdir.] locative NP] lái/qù'.

Third, there are simple and complex SVCs of the format 'Vdispl. (Vdir). lái/qù' with a patient as object, which can occur in two or three positions, respectively. These SVCs crucially involve the presence of lái' come' and qù 'go', a point which will be shown to be important, because it is their status as unaccusative verbs that allows for (internal) argument sharing (cf. section 5 below). Only these genuine SVCs are to be further examined in the remainder of the article. [START_REF] Collins | Argument sharing in serial verb constructions[END_REF][START_REF] Collins | Multiple verb movement in Hoan[END_REF] This section applies Collins' (2002) "multiple verb movement" analysis to the genuine SVCs identified in the preceding section. The main challenge is to capture the correct order of the verbs, the position of aspectual suffixes such as the perfective -le and the several positions available for the object DP. As to be demonstrated, these three issues are intricately related and can be automatically derived from the analysis as an internal argument sharing SVC, with verb movement being constrained by the two locality conditions, Minimal Link Condition and Local Move (cf. Richards 1997: 114). Minimal Link Condition (MLC) (cf. Chomsky 1995: 296) α can raise to target K only if there is no legitimate operation Move β targeting K, where β is closer to K. Local Move (cf. Chomsky 2000: 136-137) Let X have a selectional feature F, and let Y satisfy F. The Y must move to the closest possible position to X. Collins (2002: 13) further states that a verb must left-adjoin to a functional head (such as v, T or C), not to another verb, and that the trace of a verb does not block movement. 6 (30b) below implements the derivation via multiple verb movement for the complex SVC in (1), repeated here as (30a):

Internal argument sharing SVCs

(30) a.

Tā bān -chū-lái -le

[yī bǎ yǐzi]. 3SG transport-exit-come -PERF 1 CL chair 'She brought out a chair.' b. AspP 3 Asp° vP1 bān-chū-lái-le 3 bān-chū-lái v1 VP1(displacement) 3 yǐzii V1' chair 3 bān vP2 carry 3 v2 VP2(directional) 2 3 chū- v2 proi V2' 2 3 lái v2 chū VP3 exit 3 proi lái 'come'
Starting from the bottom, the unaccusative verb lái 'come' projects VP3 hosting its unique (internal) argument, pro, co-indexed with the internal argument, yǐzi 'chair', of the displacement 6 Traces in general are invisible for the MLC. In Bulgarian multiple wh-movement, for example, the object whphrase in (ic) must skip the trace of the subject wh-phrase in SpecIP (cf. Finally, the resulting sequence bān-chū-lái 'transport-exit-come' raises to Asp° and adjoins to the left of the perfective aspect suffix -le, as is standard. "Tucking in" is irrelevant here, because with respect to syntax, bān-chū-lāi behaves as one block (whose internal structure is opaque), on a par with a simple verb, and as such is maximally close to Asp° when left-adjoining. Note that Collins' account must be slightly adjusted, because Chinese has SVCs with three verbs, unlike Hoan where the SVC giving rise to the (surface) compound only features two verbs. A second vP must therefore be postulated for Chinese, given that there is no V-to-V movement. (Cf. Carstens 2002 for additional vP projections sandwiched between the VP projections in an SVC.) Chinese is also different from Hoan insofar as not all verbs have to raise, as illustrated immediately below in (31b).

The derivation for (31b) shown in (31a) proceeds in the same way, modulo the fact that the verb lái 'come' remains in situ, and that it is only chū 'exit' and bān 'carry' that raise to Asp°.

(31) a.

AspP

3 Asp° vP1 bān-chū-le 3 bān-chū v1 VP1(displacement) 3 yǐzii V1' chair 3 bān vP2 carry 3 chū v2 VP2(directional) 3 proi V2' 3 chū VP3 exit 3 proi lái 'come'
7 Collins (2002: 8) leaves open for further research the choice between PRO and pro. For Chinese, Huang (1989: 194) abandons the distinction between PRO and pro and treats then as instances of the same null pronominal, subject to the same Generalized Control Rule (GCR), stating that "an empty pronominal is controlled in its control domain (if it has one). " (p. 193). In the following, this null pronominal is represented as pro. 8 According to Collins (2002: 12), V2 is closer to v in (i) ("inner adjunction") than in (ii) ("outer adjunction"), because there is no segment intervening between the "sisters" V2 and v:

(i) [ v V1 [ v V2 v]] (ii) [ v V2 [ v V1 v]]
b.

Tā bān chū -le [yī bǎ yǐzi] lái. 3SG transport exit -PERF 1 CL chair come 'She carried out a chair.' Finally, (32b) shows the derivation for (32a), where only the displacement verb bān 'transport, carry' raises to Asp°:

(32) a.

Tā bān -le [yī bǎ yǐzi] chū-lái. 3SG transport-PERF 1 CL chair exit-come 'She brought out a chair.' b.

AspP

3 Asp° vP1 bān-le 3 bān v1 VP1(displacement) 3 yǐzii V1' chair 3 bān vP2 carry 3 chū v2 VP2(directional) 3 proi V2' 3 chū VP3 exit 3 proi lái 'come'
In (32b), bān 'carry' behaves like any other verb in a sentence with a singe verb insofar as it raises to v and then to Asp°. It is difficult to choose between the option illustrated in (32b) where lái 'come' remains in situ, on the one hand, and the possibility for lái 'come' to raise to v2 as well. At the moment, I cannot think of any test to decide this issue.

Be that as it may, the analysis presented in ( 30) -( 32) makes it possible for the first time to derive the fact that the object must directly follow the verb (sequence) that bears an aspectual suffix such as the perfective -le. This coinciding of the object position with the position directly following the aspectual suffix is a direct consequence of v-to-Asp° raising; only the verb(s) raised to the highest v can further raise to Asp°. 9 As a result, the patient DP in SpecVP1 directly below the highest vP follows the verb (sequence) located in Asp°. Furthermore, the necessity of "tucking in" to guarantee Local Move finally provides a way to derive the correct word order 9 This is the reason why (i) -(iii) are all unacceptable (also cf. both in simple and complex SVCs, and thus contrasts with previous proposals, briefly discussed in the following section.

Previous proposals -a short overview

While all the observations reported here come from the substantial Chinese literature on "directional verb compounds", formal, analytic proposals are largely absent from previous studies. Recall, though, that the Chinese literature does not talk about "compounds", but of "verbs with a directional complement" (cf. a.o. [START_REF] Fan | Dòngcí hé qūxiàng-xìng hòuzhí chéngfēn de jiégòu fēnxī [Analysis of the construction 'verb + directional item[END_REF][START_REF] Li | Dòngcí de bīnyǔ hé jiégòu de bīnyǔ [The object of the verb and the object of the phrase[END_REF][START_REF] Lu | Guānyú "qù+VP" hé "VP+qù" jùshì [On the sentence patterns 'qù + VP and 'VP + qù[END_REF], 2002;[START_REF] Yuehua | Qūxiàng bŭyŭ de yŭfă yìyì [The grammatical meaning of directional complement[END_REF]Liu/Pan/Gu 2001: 546-579).

Interestingly, they are not subsumed under the cover term liándòngshì 'SVC', applied to practically every multi-verb sequence in the Chinese literature. This very probably reflects the tacit insight that liándòngshì 'SVCs' lack internal argument sharing, present in at least a subset of "verbs with a directional complement".

To my knowledge, [START_REF] Ernst | On verb subcategorization in Chinese[END_REF] and [START_REF] Law | A note on the serial verb construction in Chinese[END_REF] are the first proposals to explicitly challenge the compound status of "directional verb compounds" and to no longer content themselves with the schizophrenic state of affairs where alleged compounds can be "split up" by the object and aspectual suffixes, and thus violate general principles such as the Lexical Integrity Hypothesis (LIH) known to hold for Chinese as well (cf. C.-T. James [START_REF] Huang | Phrase structure, lexical integrity and Chinese compounds[END_REF]. 10Limiting themselves to (what I call) simple SVCs such as sòng lái 'send come' = 'send over', [START_REF] Ernst | On verb subcategorization in Chinese[END_REF] and [START_REF] Law | A note on the serial verb construction in Chinese[END_REF] both propose a tripartite VP structure where sòng 'send' is treated as a double object verb taking two complements, the NP (xiāngzi 'suitcase' in ( 33)) and the VP lái 'come'. As a consequence, no argument sharing is involved in such structures. The alternative word order in (33b) is derived by raising the verb lái 'come' to the verb sòng 'send'. [START_REF] Law | A note on the serial verb construction in Chinese[END_REF] does not observe or comment on the fact that canonical head-to head raising as left adjunction would result in the incorrect order *lái-sòng-le, or *lái-le sòng (depending on the non-spelt out position of aspect in his structure).

Taking [START_REF] Law | A note on the serial verb construction in Chinese[END_REF] as a starting point, Paul (2005: 17-20, § 5;2008: 371-372) proposes an analysis of "directional verb compounds" as argument sharing SVCs in the sense of [START_REF] Collins | Argument sharing in serial verb constructions[END_REF] and applies it to both simple and complex SVCs, hence with pro as the internal argument in the second VP, and with binary branching instead of Law's ternary branching. However, here as well the exceptional right adjunction required in order to obtain the correct word order for V-to-V movement is not seen as a problem, either.

Zou Ke (1994) likewise obtains the adjacent order in (34b) by raising and rightadjoining the verb lái 'come' to the verb sòng 'send', and glosses over this stipulation. Note that despite postulating a complex VP structure (cf. (34a-b)), he nevertheless talks about "split" and "non-split" compounds. 12 (34) a.

Tā

[VP1 sòng-le [VP2 [NP yī běn shū] [V2 lái] ]] 3SG send-PERF 1 CL book come b. Tā [VP1 sòng-lái -le [VP2 [NP yī běn shū] [V2 tlái] ]] 3SG
send-come -PERF 1 CL book 'He sent a book over here.' (Zou Ke 1994: (2a), simplified)

The same problem of not seeing the necessity of exclusively adjoining to v instead of V and satisfying Local Move by tucking in also holds for Chen Zhishuang ( 2016) and to a certain extent for Hu Xuhui (to appear). 13 Chen Zhishuang (2016: 150) adopts my earlier proposal in Paul (2005: 17-20, § 5;2008: 371-372) to analyse "directional verb compounds" as argument sharing SVCs in the sense of [START_REF] Collins | Argument sharing in serial verb constructions[END_REF]. 14 However, she recasts this in a model based on [START_REF] Ramchand | Verb meaning and the lexicon: A first-phase syntax[END_REF] and then introduces such a range of ad hoc changes that not much remains of Ramchand's proposal, in particular not the original insights into event decomposition. For example, Chen Zhishuang (2016: 163-164) simply inverts the hierarchy of subevents from Ramchand's 'InitiatorP > ProcessP > ResultP into 'Initiator > ResultP > ProcessP', because otherwise head incorporation 12 The null pronominals present in some of his derivations are all subject-controlled, hence do not involve internal argument sharing (Zou Ke 1994: 451, (1b'')

). (i) [ IP Lǐsì i [ Infl° zǒu-jìn j ] k -le] [ VP1 [ NP1 t i ] [ V1 t k [ VP2 [ NP2 pro i ] [ V2' t j [ NP3 wūzi] ]]]]]
Lisi walk-enter-ASP house 'Lisi walked into the house.' Similarly, when stating that his "lexical-syntactic analysis […] can derive the verb compound simply by verb raising and NP-movement" (p. 443), "NP movement" refers to raising of the subject from a VP-internal position to SpecIP. As illustrated in (i), IP is assumed to be headed by aspectual markers; this is, however, straightforwardly invalidated by the acceptability of adverbs between the subject and the verb (bearing an aspectual suffix or not). Cf. [START_REF] Ernst | Functional categories and the Chinese Infl[END_REF] for demonstrating that Infl in Chinese is never overtly realized. 13 Hu Xuhui's (to appear) proposal is so convoluted and ad hoc that nearly each of its assumptions can be challenged, because not tying in with the overall syntax of Chinese. To present its various claims and invalidate them one by one would go far beyond the scope of this article. Suffice it to say that according to Hu Xuhui, the items in a "directional verb compound" are not (always) verbs; instead, "the same directional item may in fact be the phonological form of a verb, a preposition, a part of a single preposition, or even a spatial aspectual marker in different directional constructions" (cf. abstract). Importantly, he does not even address the issue that his proposal is completely at odds with the basic assumption shared by all studies over the last 60 years, viz. that "directional verb compounds" are formed by verbs (including their respective argument structure) and that the meaning of the whole is obtained compositionally (with possible metaphoric extensions). No evidence is provided for the advantage of his proposal over those based on a verbal analysis of the parts in a "directional verb compound." Nor does he mention the well-known aktionsart differences between adjacent and non-adjacent orders and the equally well-known constraints on the distribution of objects in terms of their internal structure and thematic role (patient vs location); it is therefore impossible to know how these central problems would be accounted for in his proposal. Given this regression to a status quo ante it comes as a surprise that he complains about "past studies often touch[ing] upon parts, instead of all the constructions to be discussed in this paper" and furthermore claims "to provide a comprehensive account within the generative approach, attempting to cover the major issues involved in Chinese directional constructions" (p. 6-7, emphasis mine). 14 Chen Zhishuang (2016) has an awkward and confusing way of (not) acknowledging my work. First, though both [START_REF] Paul | The "serial verb construction[END_REF] (wrongly cited as [START_REF] Paul | The "serial verb construction[END_REF]) and [START_REF] Paul | The "serial verb construction" in Chinese: A tenacious myth and a Gordian knot[END_REF] argue against word status of "directional verb compounds", they are not mentioned when compoundhood is rejected (cf. Chen's chapter 2, p. 76ff); then (on p. 143) my analysis is incorrectly likened to Zou Ke's proposal (1994), and finally (on p. 150) it is said to be adopted. In general, it is very surprising that besides her brief reference to [START_REF] Liu | Qūxiàng bŭyŭ tōngshì [An account of the directional complements[END_REF] (on pp. 271-272), no other studies written in Chinese were consulted, notwithstanding the huge amount of literature existing on "directional verb compounds" and the important generalizations made there, some of which are reported in Chen Zhishuang (2016) as well.

(another feature absent from Ramchand 2008) resulting from verb raising will produce an incorrect order. Furthermore, the different orders are not obtained from the same underlying structure as argued for above, but instead directly start out as different structures. For this, it is necessary to stipulate that the verbs lái 'come' and qù 'go' can be inserted either under ResultP (for the adjacent order) or under the additionally postulated DeicticP (for the non-adjacent order), with DeicticP either adjoined to ResultP or the additionally postulated PathP. Similarly, the directional verbs are either to be inserted under ResultP or PathP; only the displacement verbs always occur in ProcessP. All these stipulations are not only necessary to obtain the correct order of the verbs and the object, but are also appealed to when "deriving" the wellknown aktionsart differences (cf. section 4 immediately below) between the adjacent and the non-adjacent order. In brief, a substantial number of under-motivated assumptions and machinery are needed to make Chen's proposal work and in the end nothing much appears to be gained.

Aktionsart differences between adjacent and non-adjacent orders in SVCs

It has long been noted in the literature that the order where all verbs are adjacent and the ones where they are not, are associated with aktionsart differences (cf. a.o. Fan Jiyan (1963[START_REF] Zhu | Yǔfǎ jiǎngyì [On grammar[END_REF]), Lü Shuxiang (1992: 164), [START_REF] Kimura | On two functions of the directional complements lái and qù in Mandarin[END_REF], [START_REF] Yuehua | Qūxiàng bŭyŭ de yŭfă yìyì [The grammatical meaning of directional complement[END_REF], Liu/Pan/Gu (2001: 572-3), Lu Jianming ( 2002)).

Yang [START_REF] Yang | The semantic and syntactic differences of Mandarin complex verbdirection constructions[END_REF] identifies this difference with the dichotomy between achievement verbs ([+dynamic], [+telic]) and accomplishment verbs ([+dynamic], [-telic]): the adjacent order gives rise to a telic predicate, whereas the non-adjacent order results in an atelic predicate. This generalization can capture the data contrasts observed in previous works, as to be demonstrated below.

First, there is a robust consensus that the adjacent order is unacceptable in imperatives (on a par with achievement verbs such as dào 'arrive'); only the non-adjacent orders are allowed here. More precisely, according to Lu Jianming (2002: 10, (48) -(57); 13, (117) -129)), the object immediately follows the displacement verb, as illustrated by him for simple SVCs in (35), and for complex SVCs in (36): 15(35) a.

Lǎo Wáng, nǐmen bān (*qù) [yī zhāng chuáng] qù! Lao Wang 2PL transport go 1 CL bed go 'Lao Wang, you carry a bed (away from the speaker).' b.

Lǎo Wáng, jì (??-lái) yīxiē qián lái! Lao Wang send -come some money come 'Lao Wang, send some money (over to the speaker)!' [START_REF] Lu | Dòngcí hòu qūxiàng bǔyǔ hé bīnyǔ de wèizhí wèntí [On the order of the postverbal directional complement and the object[END_REF] Nǐmen tái [yī tǒng píjiǔ] shàng-qu! 2SG lift 1 barrel beer ascend-go 'Carry up a barrel of beer (away from the speaker)!' (Lu Jianming 2002: 13) Second, disallowing telic predicates, the progressive aspect zài is incompatible with the adjacent order (cf. (37b)) and requires the non-adjacent order:

(37) a.

Tā 34)) below can be easily accommodated. They observe that the non-adjacent order (i.e. duān DP lái 'serve DP come') can be used in the same context as the adjacent order (duān-lái DP 'serve-come DP') and likewise conveys the completion of the event:

(38) Shuì jiào qián , māma gěi wǒ duān [yī wǎn tàng] lái / duān-lái [yī wǎn tàng],

sleep sleep before mum for 1SG serve 1 bowl soup come/ serve-come 1 bowl soup yīdìng jiào wǒ hē -le. absolutely make 1SG drink-PERF 'Before going to sleep, mum brought me a bowl of soup and told me to absolutely drink it.' Although they do not provide any further comment, it is the presence of the continuing clause yīdìng jiào wǒ hē le 'and told me to absolutely drink it' which provides a temporal boundary for the preceding clause, whence the interpretation of the non-adjacent order duān yī wǎn tàng lái 'serve 1 bowl soup come' as a completed event, on a par with the adjacent order, duān-lái yī wǎn tàng 'serve-come 1 bowl soup', modulo the latter not requiring the continuing clause.

Xiao Xiumei (1992: 61) makes a similar observation for the pair (39a-b). While the adjacent order in (39a) indicates the completion of the event without any aspect marker, for the non-adjacent order in (39b), the aspectual suffix -le is obligatory in the same context: (39a) Tā (zuótiān) cóng shāngdiàn mǎi-lái yī jiàn yīfu. 3SG yesterday from shop buy-come 1 CL dress 'She bought a dress from the shop (yesterday).' (39b) Tā zuótiān jìn chéng le , mǎi*(-le) yī ge lùyīnjī lái. 3SG yesterday enter city SFP buy -PERF 1 CL tape.recorder come 'She went downtown yesterday and bought a tape recorder."

As demonstrated above, Yang [START_REF] Yang | The semantic and syntactic differences of Mandarin complex verbdirection constructions[END_REF] characterization of the non-adjacent order as atelic, in contrast to the telic nature of the adjacent order can nicely account for the earlier observations in the literature.

Her syntactic account of SVCs (cf. her section 4), however, suffers from various drawbacks. Although both are derived from a phrasal structure, the adjacent order is analysed as a "non-separable" complex verb and the non-adjacent order as a verb phrase. The deictic verbs lái 'come' and qù 'go' occur in the highest verb position "because of the weakest meaning". Furthermore, the situation type differences are captured by positing several "light verbs" in the sense of Lin Tzong-Hong ( 2001) such as BECOME and CAUSE. In the adjacent order, all verbs raise to the (covert) light verb BECOME. By contrast, the highest "light verb" in the two non-adjacent orders is CAUSE, and the object is hosted by a FocusP below the CAUSE projection and above the BECOME projection. Not much motivation is provided for these additional projections, and the basic feature of internal argument sharing can no longer be captured in these structures, given that lái 'come' and qù 'go' now occupy the highest position. 16 To summarize my analysis, when all verbs have raised to v and are thus adjacent, this gives rise to a telic predicate, whereas raising to v of one verb in simple SVCs and of one or two verbs in complex SVCs, respectively, results in an atelic predicate. Given that the different orders co-exist in the grammar of the same speaker, no "parametric" differences can be appealed to here, as done by Collins' (2002: 9) for the difference between Hoan and Ewe. 17

Constraints on the position of definite object DPs in SVCs

While indefinite object DPs of the form 'Num CL N' are allowed in all the three positions available in a complex SVC, the distribution of definite DP objects is more constrained. Again, this is a well-known observation and goes back at least to Zhu Dexi (1982: §9.4), but has so far not received a satisfying account.

(45) a.

* but NEG be Dad / 1 plate dish 'Mum brought in a bowl of soup, (and it was) not a dish.' (Yang Ching-Yu 2009: (14-16); my glosses and translation) While these observations are very intriguing, they involve contrast, not focus, and certainly do not warrant the projection of a FocusP within the vP. It is not obvious, either, what such a FocusP would predict for the positions of definite object DPs to be discussed in section 5 below 17 Collins (2002: 9) simply stipulates that in Hoan all verbs must raise to v (thus giving rise to surface compounds), whereas in e.g. Ewe only the first verb raises and we obtain SVCs. Given that he compares the Hoan -Ewe contrast with the contrast between English, where only one wh phrase moves in multiple questions, on the one hand, and Bulgarian, on the other, where all wh phrases move, he seems to have a parameter in mind, distinguishing the two languages. As illustrated in (51b), qù 'go' on its own is in general excluded from the sentence-final position (for all speakers) and contrasts with lái 'come' which is acceptable in this position. The ExC can therefore provide us with a clue to the asymmetry of lái 'come' vs qù 'go', holding for a subset of speakers in complex SVCs with transitive verbs (cf. ( 47) -( 48) above).

In fact, the unaccusative verb (uaV) qù where the agent (and not the locative goal) is the unique internal argument also differs semantically from the corresponding transitive verb qù 'go' with a locative noun as object, insofar as the uaV qù means 'go away, depart' rather than simply 'go' (also cf. ( 2 Gāng qù -le yī liàng xiāofángchē. just go.away-PERF 1 CL fire-engine 'There just departed a fire-engine.' (Lü Shuxiang 2000: 455) This is confirmed by Lu Jianming's (2002: 8, fn 9) observation that the sequence fēi-qù 'flygo (away)' is only acceptable in the ExC when meaning 'fly away, fly off', precisely with qù as 'leave, depart':

(53) Shù shàng yǒu wǔ zhī niǎo, fēi-qù -le liǎng zhī niǎo, tree on exist 5 CL bird fly-go.away-PERF 2 CL bird hái yǒu jǐ zhī niǎo ? still exist how.many CL bird 'In the tree there are five birds; after three have flown away, how many birds remain?' Note that no such meaning difference is observed for the uaV lái 'come' and its transitive counterpart lái 'come (somewhere)'.

Returning to the asymmetry between lái and qù in the sentence-final position of complex SVCs, summarized in (54) below, I propose that native speakers reject the sentence-final qù in (54b), because they cannot construe qù as an uaV here. This contrasts with the sequences 'Vdirqù' and 'Vdis-Vdir-qù' which clearly function as unaccusative predicates, as demonstrated in the ExC in (51a,c) above. 21 As for the speakers that do not manifest the asymmetry lái 'come' vs qù 'go (away)'in the sentence-final position of transitive complex SVCs, it seems plausible to surmise that the uaV qù has both the meaning 'go' and 'go away, leave' for them:

(54) a.

Tāmen bān -jìn -{lái /qù}-le [yī bǎ yǐzi]. 3PL transport-enter-come/go -PERF 1 CL chair b.

Tāmen bān -jìn -le [yī bǎ yǐzi] {lái / % qù}. 3PL transport-enter-PERF 1 CL chair come/ go c. Tāmen bān -le [yī bǎ yǐzi] {jìn -lái/ jìn -qù}. 3PL transport-PERF 1 CL chair enter-come/ enter-go 'They brought in a chair (towards/away from the speaker).'

The uaV status of qù in (54b) is crucial, because only with qù 'go (away)' as uaV can there be the required argument sharing. When qu is not an uaV, but the transitive verb qù 'go somewhere', whose internal argument is the locative goal (which remains covert here), then no argument sharing is possible between this locative goal and the patient DP of the displacement and directional verbs.

Conclusion

Genuine argument sharing SVCs in the sense of [START_REF] Collins | Argument sharing in serial verb constructions[END_REF][START_REF] Collins | Multiple verb movement in Hoan[END_REF] have been argued to exist in Chinese as well. They are either composed of two verbs, viz. a displacement verb (e.g. bān 'transport') plus the verb lái 'come' or qù 'go' (simple SVCs) or of three verbs, viz a displacement verb, a directional verb (e.g. jìn 'enter') plus lái or qù (complex SVCs). Crucially, lái 'come' and qù 'go' are unaccusative verbs, thus allowing for the sharing of their unique internal argument with the patient of the directional verb and the displacement verb.

The different orders observed for the verbs and their internal argument DP in simple and complex SVCs can be divided into an adjacent order 'Vdis (Vdir) lái 'come'/qù 'go' DP', on the one hand, and a non-adjacent order, on the other. More precisely, there is one non-adjacent order in the case of simple SVCs: 'Vdis DP lái/qù', and two non-adjacent orders in the case of complex SVCs: 'Vdis DP Vdir lái/qù' and 'Vdis Vdir DP lái/qù'. They can all be derived from the structure [vP1 [VPdis DPi Vdis [vP2 [VPdir proi Vdir [VP proi lái/qù ]]]]] by V-to-v movement and tucking in à la [START_REF] Richards | What moves where when in which language?[END_REF], where each verb adjoins to v as close as possible.

This analysis correctly predicts the relative order of the verbs, the possible position of aspect suffixes and the distribution of the internal argument DP, something previous works had not achieved so far. It confirms [START_REF] Collins | Multiple verb movement in Hoan[END_REF] claim that the verb raises to a functional category such as v or T, not to another verb. It also nicely fills the "gap" noticed by Collins (2002: 9) who only observes SVCs with two verbs in the languages examined by him.

Naturally, it is impossible to provide a comprehensive analysis of the entire array of phenomena involved, and in fact a monograph would be needed here.

The observed correlation between the different orders (adjacent vs non-adjacent) and the aktionsart (telic vs atelic) of the predicate is a first step in the right direction, but needs to be examined further by controling inter alia for the co-varying (in)definiteness of the internal argument DP.

There remain open questions such as the factors determining whether a given verb raises or not. This is not surprising, because the precise semantic/syntactic differences between the (i)

Tāmen bān {lái /qù}-le yī zhāng chuáng {lái /qù}. 3 PL transport come/go -PERF 1 CL bed come/go 'They moved a bed (towards/away from the speaker).' different output structures are not well-understood. It is evidently always possible to postulate some ad hoc features triggering the desired verb movement, but that would simply amount to restating the facts, as long as the phenomenon in question cannot be tied in with independently known principles of Chinese grammar.

  lái -le [yī bǎ yǐzi]. 3SG transport-enter-come -PERF 1 CL chair b. Tā bān -jìn -le [yī bǎ yǐzi] lái. 3SG transport-exit-PERF 1 CL chair come c Tā bān -le [yī bǎ yǐzi] jìn -lái. 3SG transport-PERF 1 CL chair exit-come 'She brought in a chair.'

(

  21) *Tā bǎ jiàoshì zǒu -jìn -lái -le. 3SG BA classroom walk-enter-come-PERF (22) Ta bǎ yǐzi bān -jìn -lái -le. 3SG BA chair transport-enter-come -PERF 'She brought in the chair.'

  11

  ) -(3) above):20 (52) a.Zuótiān yǐjīng qù -le sān ge rén. yesterday already go.away-PERF 3 CL person 'Yesterday, there already left 3 persons.' b.

  further below (cf. Lu Jianming 2002: 14, § 4.2.3.2 for a complete paradigm):

	(4)	a.	Tāmen rēng -shàng -qù-le [yī kuài zhuāntou]. (Fan Jiyan 1963: 46)
			3PL	throw-ascend-go-PERF 1 CL brick
		b.	Tāmen rēng -shàng -le [yī kuài zhuāntou] qù.
			3PL	throw-ascend -PERF 1 CL brick	go
		c.	Tāmen rēng -le [yī kuài zhuāntou] shàng -qù.
			3PL	throw -PERF 1 CL brick	ascend-go
			'They threw up a brick.'
	(5)	a.	Tā bān

-guò -qù-le [yī bǎ yǐzi].

(Lu Jianming 2002: 14, (

  ) are acceptable without the locative object, thus showing that it is indeed the presence of the latter that causes the unacceptability.Second, in the sequence 'Vdispl +Vdirectional + lái/qù', the only position available for a locative noun object is after the directional verb, suggesting that the locative noun is selected by the verb sequence 'Vdisplacement + Vdirectional': 5

	b. *Tāmen jìn -lái /qù fángjiān.
		3SG enter-come/go room
	(13) a.	Tā huí gōngchǎng lái /qù.
	10) 2.3. "Directional verb compounds" not to be analysed as SVCs AspP (= (5c) above: 'He carried over a chair.') 3 Asp° vP bān-le 2 carry-PERF v VP1 bān 2 yǐzii V1' chair 2 V1 V2P bān 'carry' 2 proi V2' 2 V2 V3P guò 'cross' 2 proi qù 'go' 2.3.1 'Vdirectional + locative NP + lái 'come'/qù 'go' While 'displacement V + lái/qù 'come/go' in (7) -(9) above instantiates a simple SVC, this is not the case for the sequence 'directional verb + locative NP + lái/qù' (cf. (11) -(13) below). No argument sharing is involved here; the locative nouns selected for by the directional verbs shàng 'ascend', xià 'descend', jìn 'enter', chū 'exit', huí 'return', guò 'cross' are clearly not the internal argument of the deictic verbs lái 'come' or qù 'go'. This is also reflected in the availability of a single object position only (cf. (11b-13b)), an observation omnipresent in the literature (cf. a.o. Fan Jiyan 1963: 74; Liu Yuehua 1980, Lu Jianming 1985, 2002). (11) a. Tā shàng shān lái /qù. (Lu Jianming 2002: 10, (58) -(65)) 3SG ascend mountain come/go 'He climbs the mountain (towards/away from the speaker).' b. *Tā [shàng -lái /-qù] shān. 3SG return factory come/go 'He returned to the factory (towards/away from the speaker).' b. *Tā huí -lái /qù gongchǎng. 3SG return-come/go factory It seems therefore plausible to analyse lái/qù as matrix verbs preceded by an adjunct clause: 4 (14) [TP DPi [vP [adj.cl. proi Vdirectional locative NP] lái 'come'/qù 'go']]. The analysis proposed in (14) is different from the traditional view. Although the latter does observe the constraint on the object position and explicitly mentions that the subject is the agent of lái/qù 'come/go' here (not the locative NP), it still subsumes these cases under the same label "verbs with a directional complement" alongside genuine (simple and complex) SVCs. (Cf. a.o. Fan Jiyan 1963: 74 Liu Yuehua 1980, Lu Jianming 1985). 2.3.2 Locative nouns as objects in "directional verb compounds" In fact, locative nouns as objects in "directional verb compounds" in general can only occur in (Lu Jianming 2002: 9 (30) -(33)) ball roll bed under go-PERF 'The ball rolled under the bed.' b. *Píqiú gǔn-qù [PostP chuáng dǐxià] le. ball roll-go bed under SFP (16) a. Mìfēng fēi [PostP fángjiān lǐ] lái -le. bee fly room in come-PERF 'The bee flew into the room.' b. *Mìfēng fēi-lái [PostP fángjiān lǐ] le. bee fly-come room in SFP Tā zǒu -jìn jiàoshì lái. 3SG walk-enter classroom come 'He walked into the classroom (toward the speaker).' b. *Tā zǒu -jìn -lái jiàoshì. 3SG walk-enter-come classroom c. *Tā zǒu jiàoshì jìn -lái. 3SG walk classroom enter-come Note that (15b) and (16b(17) a. (18) Tā pǎo (*mén) chū mén lái /qù (*mén).
		3SG ascend-come/-go mountain
	(12) a.	Tāmen jìn fángjiān lái /qù.
		3SG enter room come/go
		'They entered the room (towards/away from the speaker).'

one position, irrespective of the number of verbs involved. No SVCs are involved here, as argued for in detail below.

First, in contrast to simple SVCs 'Vdispl + lái/qù 'come/go' where the patient DP can occur in two positions (cf. (6-8) above), a locative noun as object again must immediately follow the displacement verb: 'Vdispl [locative NP] lái/qù : (15) a.

Píqiú gǔn [PostP chuáng dǐxià] qù-le. 3SG run door exit door come/go door 'She ran out of the door (toward/away from the speaker) (19) Hǎi'ōu fēi (*hǎi) guò hǎi qu (*hǎi).

[START_REF] Chao | A grammar of spoken Chinese[END_REF]

: 477) seagull fly sea cross sea go 'The seagull flew away over the sea.'

  compounds are not discussed any further in the remainder of the article.

	(27) a.	Tā [V° zǒu-chū]-le fángjiān.
		3SG walk-exit-PERF room
		'She walked out of the room.'
	b.	*Tā zǒu -le fángjiān chū.
		3SG walk-PERF room exit
	(28) a.	Tāmen tiào -shàng -le	diànchē.
		3PL	jump-ascend-PERF tram
		'They jumped onto the tram.'
	b.	*Tāmen tiào -le	diànchē shàng.
		3PL	jump-PERF tram ascend
	In fact, (27a) and (28a) illustrate the same case as (23), repeated in (29a) below, modulo the
	fact that in (29a), the [Vdispl + Vdir] compound is the predicate of an adjunct clause preceding
	the matrix verb lái 'come'.
	(29) a.	[Tāi [adj.cl. proi zǒu -jìn jiàoshì ] lái].	(= (23) above)
		3SG	walk-enter classroom come
		'He walked into the classroom (toward the speaker).'
	b.	Tā [V° zǒu -jìn ] jiàoshì le.
		3SG	walk-enter classroom SFP
		'He walked into the classroom.'
	(24) a.	Tā [V° chuān-shàng]-le yīfu.
		3SG	wear -asend -PERF clothes
		'He put on clothes.'
	b.	*Tā chuān -le yīfu shàng.
		3SG wear -PERF clothes ascend
	(25) a.	Tā shōu -huí -le	wénjiàn.
		3SG receive-return-PERF documents
		'He recovered the documents.'
	b.	*Tā shōu -le		wénjiàn huí.
		3SG receive-PERF documents return
	(26) a.	Tā ná -chū-le		shǒujī.
		3SG take-exit-PERF cell.phone
		'She took out the cell phone.'
	b.	*Tā ná -le	shǒujī	chū.
		3SG take-PERF cell.phone exit

  bān 'carry' in VP1.7 The VP3 headed by lái 'come' in turn merges with the directional verb V2 chū 'exit', whose internal argument is again pro, co-indexed with yǐzi 'chair' in SpecVP1. Since chū 'exit' is closest to the target, i.e. v2, it must raise and left-adjoin to v2 first (as per the MLC), before lái 'come' raises to v2 as well. Since by Local Move, lái 'come' must adjoin as close as possible to v2, it "tucks in" (cf. Richards 1997) and we obtain the order chūlái 'exit-come'. 8 VP1 headed by bān 'carry, transport' is projected: its internal argument yǐzi 'chair' occurs in SpecVP1 and vP2 occupies the complement position. Being closest to v1, the verb bān 'carry' raises first: [v1 bān'carry' v1]; the sequence chū-lái 'exit-come' likewise raises and "tucks in" immediately left-adjacent to v1: [v1 bān 'carry' [v1 chū-lái 'exit-come' v1]].

			Collins 2002: 10, referring to Chomsky
	1995: 304):
	(ia)	[ CP C IP]	(underlying structure)
	(ib)	[ CP 'who' [ C' C IP]]	(MLC)
	(ic)	[

CP 'who' [ C' 'whom' [ C' C IP]]] (Local Move) verb

  You carry the table over there (i.e. away from the speaker)!' d.

	c.	Nǐmen bān	[yī zhāng zhuōzi] guò -qù!
		2PL	transport 1 CL	table cross-go
		'
					10)
	(36) a.	Rēng [yī ge jiǔpíng]	xià	-lái !
		throw 1 CL wine.bottle descend-come
		'Throw down a wine bottle (towards the speaker)!
	b.	*Rēng -xià	-lái [yī ge jiǔpíng]!
		throw-descend-come 1 CL wine.bottle

  There is a broad consensus in the literature subsequent[START_REF] Zhu | Yǔfǎ jiǎngyì [On grammar[END_REF] that definite object DPs are banned from the postverbal position in the adjacent order. While native speakers in general share the judgements for inanimate DPs (hence the unacceptability of (47a) below with wǒ de shūzhuō 'my desk', in addition to Zhu's (45a) above), the situation is less clear-cut for proper names (Xiǎo Míng) and definite animate DPs (wǒ de māo 'my cat') in (48):

	b.	Tā ná [DP nà běn xīn de shū] chū-lái.
	(51) a.	3SG take [Gāng] zǒu -jìn -lái /-qù-le [yī ge háizi]. that CL new SUB book exit-come
		just	walk-enter-come/ -go-PERF 1 CL child
	c.	Tā ná -chū [DP nà běn xīn de shū] lái.
	b.	3SG take-exit [Gāng] zǒu -jìn -le [yī ge háizi] lái /*qu. that CL new SUB book come
		just	walk-enter-PERF 1 CL child come/ go
		'He took out that new book.'
	c.	[Gāng] zǒu -le	[yī ge háizi] jìn -lái / jìn -qù.
	(46) a.	*Tā jiào-chū-lái {Lǎo Wáng / tā} just walk-PERF 1 CL child enter-come/ enter-go
		3SG call-exit-come Lao Wang / 3SG
	b.	Tā jiào {Lǎo Wáng / tā } chū-lái 18 'A child just walked in (into the direction of/away from the speaker).'
		3SG call Lao Wang / 3SG exit-come
	c.	Tā jiào-chū {Lǎo Wáng / tā } lái
		3SG call-exit Lao Wang / 3SG -come
		'He called for/summoned Lao Wang/him.'
	(47) a.	*Tā yīgerén bān		-guò -qù-le	[wǒ de shūzhuō].
		3SG alone transport-cross-go-PERF 1SG SUB desk
	b.	Tā yīgerén bān		-le	[wǒ de shūzhuō] guò -qù.
		3SG alone transport-PERF 1SG SUB desk	cross-go
	c.	??Tā yīgerén bān	-guò -le	[ wǒ de shūzhuō] qù.
		3SG alone transport-cross-PERF 1SG SUB desk	go
		'He moved my desk over (away from the speaker) all on his own.'
	(48) a.	%Tā gǎn -chū-qù-le Xiǎo Míng/[wǒ de māo].
		3SG chase-exit-go-PERF Xiao Ming/ 1SG SUB cat
	b.	Tā gǎn -le Xiǎo Míng/[wǒ de māo] chū-qù.
		3SG chase-PERF Xiao Ming/ 1SG SUB cat exit-go
	c.	??Tā gǎn -chū -le Xiǎo Míng/ [wǒ de māo] qù.
		3SG chase-exit PERF Xiao Ming/ 1SG SUB cat go
		'He chased away/drove out (away from the speaker) Xiao Ming/my cat.'

The inclusion of intransitive verbs might at first sight seem surprising. Cf. section 5 below for further discussion.

The Latin-stem based meaning is used for the glosses here to emphasize their word status, the more so as these directional verbs can all combine with the deictic verbs lái 'come' and qù 'go' and then indicate movement in a

(11) -(13) thus show the same structure as (i) below (cf. Fan Jiyan 1963: 82): (i) [ TP1 Wǒmen i [ vP [ adj.cl. pro zǒu ] qù]] háishi [ TP2 pro i [ vP [ adj.cl. pro zuò chē] qù]]? 1PL walk go or sit train go 'Should we go [there] on foot or by train?'

According to Lu Jianming (2002: 17, footnote 12), this constraint on locative objects is not observed in Taiwanese Mandarin nor in Southern Min and Cantonese.

To my knowledge, Fan Jiyan (1963: 70-71) is the only one among the Chinese linguists to explicitly challenge the idea that the object as well as aspectual suffixes are "inserted" (binyǔ chárù shuō 'object insertion hypothesis').

Nevertheless, Law (1996) calls this structure an SVC. Given that he also treats as SVC sentences with an adjunct clause preceding the main verb (as in (11) -(13) above), this voids the term SVC of its substance, because not referring to a unique construction with a fixed set of syntactic and semantic properties (cf. Paul 2008 for discussion).

[START_REF] Lü | Tōngguò duìbǐ yanjiū yǔfǎ [Grammar research by comparison[END_REF]

164) also states that the adjacent order 'Vdis-Vdir-lái' is not acceptable in imperatives, but includes 'Vdis-Vdir DP lái/qù' as a second possible order in imperatives.

As pointed outby Zhu Dexi (1982: 130), when stress is not on jiào 'call' as intended in (46b), but on chū 'exit', then the sequence is interpreted as 'tell Lao Wang/him to come out'; in other words, it is analysed as a control construction, not as a complex SVC.

The uaV qù 'go away' is thus like the uaV zǒu 'leave' modulo the component of movement away from the speaker present in qù 'go away'.

Somewhat surprisingly, the speakers rejecting sentence-final qù 'go' in complex SVCs accept it in simple SVCs:

 [START_REF] Kimura | On two functions of the directional complements lái and qù in Mandarin[END_REF]explicitly talks about an aspectual opposition between the two orders, where the adjacent order is said to imply a "static aspect" (as the result of previous motion) and the non-adjacent order a "motion aspect". The evidence cited by [START_REF] Kimura | On two functions of the directional complements lái and qù in Mandarin[END_REF] can be easily recast into the dichotomy telic vs atelic posited by [START_REF] Yang | The semantic and syntactic differences of Mandarin complex verbdirection constructions[END_REF]. More precisely, the atelic nonadjacent order(s) are compatible with process-related manner adverbs and auxiliaries and can be presented as consecutive events in a listing. The adjacent order is excluded from these contexts:

( When listing consecutive events and when conveying the simultaneous occurrence of events with e.g. yī biān 'one side'…. yī biān 'one side' = 'at the same time', only the nonadjacent order is acceptable:

(42) Xiǎohuā zuò-qǐ -lai , rǒu -le rǒu yǎnjing, xiǎng-le xiǎng, Xiaohua sit rise-come rub-PERF rub eye think -PERF think gǎnjǐn ná qǐ bàozhǐ lai /?? [ná -qǐ -lai ] bàozhǐ, dǎkāi-le. hastily take rise newspaper come/ take-rise-come newspaper open -PERF 'Sitting up, Xiaohua rubbed his eyes and thought for a while, then took up the newspaper hastily and opened it.' (43) Lǎoshi yī biān jiūzhù Xiǎopō de lǐngzi, [START_REF] Kimura | On two functions of the directional complements lái and qù in Mandarin[END_REF]: 271, (10)) teacher 1 side hold.fast Xiaopo SUB collar yī biān {chǎo -qǐ bǎnzi lai / ??[chǎo -qǐ -lai] bǎnzi } 1 side clutch-rise paddle come clutch-rise-come paddle 'In one hand the teacher grasped Xiaopo by the collar, and in the other hand he grasped the paddle.' Finally, only the non-adjacent order is acceptable as complement of modal auxiliaries: (44) Tā yào {tái-qǐ [zuǒ shǒu] lai / ?? [tái-qǐ -lai ] zuǒ shǒu} 3SG will lift-rise left hand come / lift-rise-come left hand 'He will raise his left hand. [START_REF] Kimura | On two functions of the directional complements lái and qù in Mandarin[END_REF]: 272, ( 13))

The definite object DP wǒ de shūzhuō 'my desk' is excluded from the postverbal position with the adjacent order (47a), but acceptable in the non-adjacent order (47b). The marginality of (47c) in fact involves still another factor, i.e. the asymmetry between lái and qù in sentencefinal position observed for a subset of speakers and to be discussed further below (cf. ( 54)). While Yang Ching-yu ( 2009) marks (48a) with the proper name as unacceptable, native speakers consulted accepted it, hence the mark "%" indicating the heterogeneity of judgements. (48b) is the order reported as acceptable in the literature for definite object DPs in complex SVCs and confirmed by the native speakers consulted. The marginal character of (48c) with qù 'go' on its own in sentence-final position again is not linked to the definite character of the object DP, but to the sentence-final position of qù 'go', given that the same subset of native speakers likewise rejected the order in (48c) with an indefinite object DP such as yī zhī māo '1 CL cat' = 'a cat'.

The conditioned ban on definite DPs in the postverbal position of the adjacent order, contrasting with the acceptability of inanimate DPs in all of the three possible positions, is reminiscent of the Definiteness Effect (DE) observed in existential constructions (ExC), where definite DPs are in general excluded from the postverbal position (cf. Huang 1987, Paul/Lu/Lee (2020)). Interestingly, here as well proper names are an exception insofar as they are allowed postverbally in list contexts (cf. (Jīntiān) lái -le Lǐ lǎoshī , Wáng lǎoshī hé tāmen de xuéshēng. today come-PERF Li professor Wang professor and 3PL SUB student 'Today arrived Prof. Li, Prof. Wang and their students. ' Zhu Dexi (1982: 130) in a certain way draws this parallel when stating that a definite DP must occupy the preverbal subject position in the case of SVCs with an intransitive motion verb such as fēi 'fly' and is excluded from the postverbal position:

(50) a.

Nà zhī cāngyíng yòu fēi-jìn -lái -le. that CL fly again fly-enter-come-PERF 'That fly has again flown in.' b.

Lǎo Wáng pǎo-huí -qù-le. Lao Wang run-return-go-PERF 'Lao Wang has run back (away from the speaker). [START_REF] Zhu | Yǔfǎ jiǎngyì [On grammar[END_REF] observation must be seen against the backdrop of ExC with complex SVCs featuring intransitive motion verbs (cf. Lu Jianming 2002: 12-13; (104-110): 19 19 In the following, I concentrate on complex SVCs, because there seems to be only one DP position available with simple SVCs in the existential construction, i.e. lái 'come' in (i) preferrably raises to v (cf. Xiao Xiumei 1992: 59): (i) Fēi-{lái } -le [yī zhī cāngyíng] {??lái}. fly -come-PERF 1 CL fly come 'There has a fly come in.' (Lu Jianming 2002: 8, (11))