Paul Massé

Sabine Choppin
email: sabine.choppin@unistra.frlucia.chiummiento@unibas.it

Lucia Chiummiento

Gilles Hanquet

Francoise Colobert

Françoise Colobert

0]-metacyclophane

Keywords: myricanol, target-oriented synthesis, diarylheptanoid, natural product, macrocycle, Suzuki-Miyaura cross-coupling, RCM, Alzheimer's disease biological activities

come   L'archive ouverte pluridisciplinaire

Myricanol 1 was extracted from the stem bark of Myricacae species, trees that produce bayberries, and more particularly from Myrica Nagi in 1970 by Whiting and co-workers. 1 There is a vivid interest in the community for this strained meta,metabridged phenolic diarylheptanoid 1 which displays a very intriguing structure with its biaryl system linked by an oxygenated aliphatic heptyl chain. [2][3] Besides, it exhibits many different biological activities such as anti-oxidant and antiandrogenic. 4 Very recently, it was discovered that 1 displays as well anti-inflammatory along with anti-obesity and anti-muscle atrophy properties. 5 This [7,0]-metacyclophane 1 also features anti-cancer virtues. It was shown to undoubtedly strive against human lung adenocarcinoma A549 cells. 6 Furthermore, Dickey et al found that 1 potently reduces the levels of the microtubuleassociated protein tau in both cultured cells and ex vivo mouse brain slices, which results in an anti-Alzheimer's disease effect, notably owing to the (-)-aS,11R-myricanol enantiomer which has been separated by chiral HPLC. 7 Scheme 1 State-of-the-art on macrocylizations leading to (±)-myricanol Three total syntheses have been previously described in a racemic way. The first one was reported by Whiting et al in 1983. 8 They achieved the challenging macrocyclization in 7% yield by a nickel-mediated intramolecular oxidative coupling from a linear diiodide diarylheptanoid. Dickey and coworkers reported in 2015 the second total synthesis of racemic myricanol 1. 7 They performed an intramolecular Suzuki-Miyaura cross coupling between an aryl boronic acid pinacol ester and an aryl iodide delivering the macrocycle in 22% yield. Colobert et al carried out a Suzuki-Miyaura domino reaction to obtain the expected 13-membered cycle in 12% yield (Scheme 1). 9 Scheme 2 Retrosynthetic analysis of 1

Based on our deep-rooted enthusiasm for the chemistry of bioactive natural products, 10 we were eager to perform the total synthesis of this uncommonly strained compound. Meta-meta cyclic diarylheptanoids are considered as congested cyclophanes because of their high ring strain due to the short heptyl bridge. 2a,3 As for all cyclic compounds, macrocyclization is the most critical step, which determines the overall efficiency of a synthetic route. 3 To the best of our knowledge, endeavor of macrocyclization to prepare meta,meta-bridged diarylheptanoids in the literature other than by biaryl coupling have failed so far (Heck coupling and Thorpe-Ziegler reaction). 11 However, none of those routes have envisioned a convergent approach of this 13-membered strained compound 1 via a sequence of two key reactions: a Suzuki-Miyaura coupling followed by a ring closing metathesis (RCM). RCM is often efficiently applied for the construction of strained natural compounds and with a large variety of substrates. 12 For instance, Kundig et al prepared a strained 12-membered macrolactone bearing an ortho,meta diarylheptanoid performing a RCM in presence of HGII in an optimized yield of 37%. 13 A large variety of catalysts are available for RCM as GII, HGII, but also more exotic catalysts like Mauduit's (Umicore M71), Nolan's (Umicore M2) and Grela's (nG-I2) which could achieve this challenging macrocylization (Scheme 5). 14 Herein, we describe a new convergent retrosynthetic pathway of 1 that could be arisen from 2 by RCM, itself stemming from the Suzuki-Miyaura coupling from key building blocks 3 and 4, envisaged respectively from commercially available compounds 5 and 6 (Scheme 2). As depicted in Scheme 3, the first building block 10 has been synthetized in 5 steps on a multigram scale without any required purification from the readily available benzylprotected phenol 6. 15 The ester moiety was derivatized into the corresponding Weinreb amide in toluene in remarkable yield using AlMe3 and the corresponding hydroxylamine hydrochloride. The latter underwent a regioselective iodination in ortho position of the benzyl ether using I2 as well as Ag2SO4 to give 7 in 83% yield. 9 Subsequent vinylation of the amide with a Grignard reagent allowed us to isolate the α,β-unsaturated ketone 8 in a quantitative yield upon quick hydrolysis with a strong acid to avoid the formation of a side-product coming from the Michael addition of the released hydroxylamine onto 8. 16 Luche reduction furnished 9 in 88% yield with complete chemoselectivity. Consecutive protection of the formed allylic carbinol as its corresponding benzyl ether afforded the first building block 10 with an overall yield of 58%. A variant protecting group (4, bearing a THP group) was envisaged to perform the remainder of the synthesis. As outlined in Scheme 4, the synthesis of the second key coupling partner 3 started with commercially available trimethoxybenzaldehyde 5 which was regioselectively demethylated in ortho position of the aldehyde using a Lewis acid. The reaction has to be performed under 20 °C to avoid a second competitive demethylation. Then, regioselective iodination of the aromatic cycle was accomplished and provided 11 exclusively in 51% yield. It should be noted that a complete conversion was observed; however, aryl iodide was trapped in the silver salts and remained unextractable; many experimental conditions were screened to improve yield, without any success. Upon allylation on the aldehyde with a Grignard reagent, homoallylic alcohol was afforded in excellent yield. Thereupon, the formed carbinol was cleaved using triethylsilane in acidic medium, 17 followed by the addition of a solution of TBAF due to the resulting partial triethylsilylation of the phenol group, thus affording 12. Subsequently, the latter was subjected to a protection to give its corresponding benzyl ether 13 in 95% yield. Aryl iodide 13 was treated with t-BuLi and isopropoxypinacolborane at -78 °C in dry hexane to provide 14 as a boronic acid pinacol ester. Finally, 3 was prepared on exposure to an aqueous solution of KHF2 in MeOH in 89% yield over two steps. 3 was reached in 7 steps with an overall yield of 25%. 18 Scheme 5 First RCM attempts. Reagents and conditions: (a) Pd(PPh3)4, K2CO3, TBAB, H2O, 100 °C, 16 h, 83%.

With both partners 3 and 10 in hand, we were able to synthetize the biaryl 15 by Suzuki-Miyaura coupling in the presence of palladium(0) (Scheme 5). We have to point out that with the pinacol boronic ester 14, no reaction occurred; also, we were never able to synthetize the corresponding boronic acid, justifying the selection of the more reactive trifluoroborate salt. 19 Moreover, the yield was low when the reaction was performed in dioxane (28%). By modifying the ratio dioxane/H2O up to H2O only, yield was increased to 83%. With Buchwald conditions (palladium(II) acetate and SPhos ligand), we ended up with the isomerization of the terminal double bond.

To finalize the preparation of myricanol 1, first RCM assays were next attempted with the seco-precursor 15 by screening various solvents (CH2Cl2, PhMe, DCE, Et2O, H2O) catalysts (GI, GII, HGII, M71, M2) and temperatures (from 25 to 110 °C). None of those experimental conditions gave us rise to the expected cyclized compound 16 even in the required high dilution conditions (Scheme 5). The benzyl-protected allylic alcohol being a type III olefin, 20 hence less reactive, we therefore tried with the free allylic alcohol along with its corresponding α,βunsaturated ketone (likely to be more prone to macrocyclize due to the presence of the sp 2 carbon center). Notwithstanding, it was impossible to deprotect regioselectively the benzyl group on the allylic alcohol versus the benzyl-protected phenols. Consequently, we tried the Suzuki-Miyaura coupling between our trifluoroborate salt 3 and ketone 8. Unfortunately, we could not access 18 directly (Path A, Scheme 6). Ketones are apparently not compatible with those conditions. Hence, we then attempted the coupling with 9 bearing the free hydroxy group instead, which afforded 17 in order to get by its further oxidation the corresponding ketone 18. In this way, 17 was obtained in low yield (Path B, Scheme 6). Based on these results, we further proceeded to a three-step sequence using 4 (THPprotected 9 derivative) that was coupled with 3 to obtain biaryl 2 in excellent 86% yield. Finally, removal of THP group and oxidation using MnO2 followed smoothly (Path C, Scheme 6). Further RCM attempts on 17 gave us unexpected results: we obtained two regioisomers 19 and 19'. Allylic alcohol isomerized into the corresponding ethyl ketone, 21 and terminal double bond isomerized once, but also twice to be conjugated with the aromatic core (both compounds were obtained in a 1:1 ratio). 22 The failure of the RCM of 17 could be explained by the free rotation of the biaryl axis which increase the difficulty of the two terminal alkenes to cross path. The presence of a Csp 3 leads also to a more strained chain compared to the presence of a Csp 2 . [START_REF] Whiting | 091 mmol) in toluene (180 mL) was degassed for 30 minutes under a flow of argon. The reaction mixture was heated at reflux. Then, Grubbs 2 nd generation (20 mol%, 15 mg, 0.018 mmol) was added in one portion. The reaction mixture was stirred at reflux for 16 h. The reaction mixture was filtered through a pad of both activated charcoal and silica gel and solvent was evaporated under reduced pressure to afford 20 (20 mg, 35 mmol, 39%) as an oil. 1 H NMR (500 MHz, Chloroform-d) δ 7[END_REF] As for RCM attempts on 18, we were quite pleased to see by 1 H NMR that we obtained the expected cyclized compound. Nonetheless, we realized we formed the head-to-tail dimer 20 thus involving a C2 symmetry as evidenced from HR mass spectrum. 24 Changing the solvent, the catalyst, lowering the concentration or adding the starting material via a syringe pump over a long period unfortunately did not circumvent our issue. (Table 1) To overcome this synthesis drawback, we next sought to solicit the concept of Relay RCM (RRCM). 25 RRCM involves the incorporation of a temporary pentenyl tether containing a terminal olefin to initiate the catalytic process. Once you add the catalyst, the ruthenium carbene can be formed on the terminal olefin, a 5-membered ring is extruded which leads to the desired metal carbene that can undergo further cyclization. Porco et al reported in 2004 the synthesis by RRCM of oximidine III, a 12membered macrocycle. 26 They managed to obtain a yield of 71% for the macrocyclization step whereas with a classical RCM they could not get any traces of the expected compound. In our case, we chose to put a malonate group onto the temporary tether to improve the efficiency of our RRCM by dint of the Thorpe-Ingold effect. 25 Starting from 9, we performed the cross-metathesis with dimethyl allylmalonate in the conditions described by Lipshutz et al, with a surfactant and copper iodide as an additive thus affording 21. 27 Subsequently, both deprotonation of the methylene-active malonate motif followed by the trapping with allyl bromide and protection of the allylic alcohol with a THP group were quantitative. THP was a protecting group of choice given that it is easily accessible and easy to orthogonally deprotect. Afterwards, the Suzuki-coupling between 22 and 3 was implemented in a great yield and RRCM assays were attempted. RRCM assay on 23 was not conclusive: we extruded the 5-membered ring but the formed carbene did not react further, we therefore ended up with 2. We proceeded to the RRCM on free allylic alcohol 24, but we obtained the same results as with the RCM: isomerization of allylic alcohol into ethyl ketone and isomerization of the terminal double bond. 25 bearing the carbonyl function ended up degraded in the RRCM conditions (Scheme 7). The free rotation of the biaryl axis combined with the high congestion of the desired compound could undeniably explain the uncompletion of the reaction. Accordingly, we attempted to make the less strained 14-membered cycle analogue, more prompt to undergo cyclization, as a proof of concept. Instead of using commercially available allyl Grignard reagent to prepare the RCM precursors, chain was introduced via an in situ homoallylic Grignard reagent on 11. Successive reduction, protection of 26, lithium-iodine exchange, trifluoroboration, Suzuki-Miyaura coupling on 27 and 4, deprotection and oxidation proceeded smoothly to procure 29. Unfortunately, RCM attempts on 28 gave us notably a 28-membered macrocycle 30 among a myriad of isomerized products (adding benzoquinone to prevent isomerization did not succeed). 28 29 with the ketone gave us also a head-to-tail dimer 31 in 37% yield (Scheme 8).

In conclusion, a 26-membered macrocycle and two 28membered macrocycles have been successfully synthetized using RCM in high dilution conditions. No traces of 13-or 14membered cyclized products were spotted even with RRCM. We can infer that the strain outpaces the reactivity, even in our attempts to prepare the 14-membered macrocycle.

Scheme 3

 3 Scheme 3 Preparation of the first building-block 10 Reagents and conditions: (a) CH3NHOCH3•HCl, AlMe3, PhMe, r.t., 24 h, 99%; (b) I2, Ag2SO4, CH2Cl2, r.t., 3 days, 83%; (c) vinylmagnesium bromide, THF, 0 °C, 1 h, 99%; (d) NaBH4, CeCl3•7H2O, MeOH, -78 °C, 0.5 h, 88%; (e) NaH, BnBr, NaI, DMF, 0 °C to r.t., 1.5 h, 91%; (f) DHP, PPTS, CH2Cl2, r.t., 24 h, 79%.

Scheme 4

 4 Scheme 4 Preparation of the second coupling partner 3 Reagents and conditions: (a) AlCl3, CH2Cl2, r.t., 3 h, 81%; (b) I2, Ag2SO4, CH2Cl2, r.t., 3 days, 51%; (c) allylmagnesium bromide, THF, 0 °C, 0.5 h, 87%; (d) i. TES, TFAA, CH2Cl2, 0 °C, 1.5 h; ii. TBAF, THF, 70%; (e) BnBr, NaH, NaI, DMF, 1.5 h, 0 °C to r.t., 95%; (f) i. t-BuLi, hexane, -78 °C; ii. i-PrOBpin, -78 °C to r.t., 2.5 h; (g) KHF2, H2O, MeOH, r.t., 1.5 h, 89% (over 2 steps).

Scheme 6

 6 Scheme 6 Different routes towards 18 Reagents and conditions (a) Pd(PPh3)4, K2CO3, TBAB, H2O, 100 °C, 16 h; (b) PPTS, MeOH, CH2Cl2, 60 °C, 3 h, 99%; (c) MnO2, CH2Cl2, 40 °C, 3 h, 66%.

Scheme 7

 7 Scheme 7 Synthesis of RRCM precursor and subsequent RRCM attempts Reagents and conditions (a) dimethyl allylmalonate, GII, CuI, TPGS-750-M, H2O, 40 °C, 16 h, 55%; (b) DHP, PPTS, DCM, r.t., 16 h, 99%; (c) NaH, allylbromide, THF, 60 °C, 1.5 h, 99%; (d) 3, Pd(PPh3)4, K2CO3, TBAB, H2O, 100 °C, 16 h, 74%; (e) PPTS, MeOH, CH2Cl2, 60 °C, 3 h, 99%; (f) MnO2, CH2Cl2, 40 °C, 3 h, 64%; (g) GII, PhMe (1 mM), 110 °C, 16 h.

Scheme 8

 8 Scheme 8 Synthesis of corresponding 14-membered macrocycle precursor and subsequent RCM attempts Reagents and conditions (a) butenylbromide, Mg, THF, 0 °C, 0.5 h, 98%; (b) i. TES, TFAA, CH2Cl2, 0 °C, 1.5 h; ii. TBAF, THF, 80%; (c) BnBr, NaH, NaI, DMF, 1.5 h, 0 °C to r.t., 47%; (d) i. t-BuLi, hexane, -78 °C; ii. i-PrOBpin, -78 °C to r.t., 2.5 h; (e) KHF2, H2O, MeOH, r.t., 1.5 h, 93% (over 2 steps); (f) 4, Pd(PPh3)4, K2CO3, TBAB, H2O, 100 °C, 16 h; (g) PPTS, MeOH, CH2Cl2, 60 °C, 3 h, 35% (over 2 steps); (h) MnO2, CH2Cl2, 40 °C, 3 h, 37%. (i) GII, CH2Cl2 (1 mM), 16 h, 11% (j) GII, PhMe (1 mM), 16 h, 37%.

Table 1

 1 Unexpected results in the course of RCM attempts on 19 and 20

	Entry	Catalyst	Solvent	Concentration	Dimer yield
	1	GII	CH 2 Cl 2	2 mM	20%
	2	GII	PhMe	2 mM	30%
	3	GII	PhMe	0.5 mM	39%
	4	M71	PhMe	0.5 mM	37%
	5	GI	PhMe	0.5 mM	n.o.
	6	nG-I 2	PhMe	1 mM	17%
	Reagents and conditions (a) GII, PhMe (2 mM), 110 °C, 16 h, 35%.

Acknowledgment

We thank the CNRS France (Centre National de la Recherche Scientifique) as well as the University of Strasbourg, and Paul Massé is grateful to the French ministry of research and development for financial support. We are also really grateful to Marc Mauduit who provided us his catalyst.

Supporting Information

YES (this text will be updated with links prior to publication)

Primary Data

NO (this text will be deleted prior to publication)


Yoko Sakai-Otsuka

Yoshiharu Nishiyama

Jean-Luc Putaux

Martin Brinkmann

Toshifumi Satoh

Wen-Chang Chen

Redouane Borsali

Competing Molecular Packing of Blocks in Lamellaforming Carbohydrate-block-Poly(3-hexylthiophene) Copolymer

A molecular packing model of poly(3-hexylthiophene)-block-peracetylated maltopheptaose (P3HT-b-AcMal7) was proposed based on the X-ray and electron diffraction measurements. The P3HT and AcMal7 segments are confined in the lamellae in which the AcMal7 segments are aligned side-by-side. The extended P3HT chain segments are tilted with respect to the lamellae plane and strongly π-stacked. This molecular arrangement results from a subtle balance between segregation strength of the P3HT and AcMal7 blocks, strong π-π interactions of the P3HT backbones, geometrical mismatch between two blocks, space filling requirement and entropic penalties. The small-angle X-ray scattering (SAXS) analysis above the melting temperature of P3HT block indicates a strong segregation strength between P3HT and AcMal7 blocks. Differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FT-IR) and SAXS measurements underline the improved thermal stability of P3HT crystalline domains in the phaseseparated P3HT-b-AcMal7.

INTRODUCTION

Block copolymers containing p-conjugated semiconducting polymers have attracted attention at the frontier of polymer chemistry and optoelectronic engineering due to their exceptional physical properties and wide structural tunability. [START_REF] Segalman | Block Copolymers for Organic Optoelectronics[END_REF][START_REF] Lee | Challenges and Opportunities in the Development of Conjugated Block Copolymers for Photovoltaics[END_REF] They possess high potential for applications in optoelectronic technology including low-cost and flexible organic photovoltaic devices. In the past decade, the external power conversion efficiencies (EPCEs) of single junction donor-acceptor (D/A) bulk-heterojunction (BHJ) solar cells has continuously improved, reaching 14 % 3 owing mostly to the development of new materials, such as p-type low-band-gap conjugated polymers [START_REF] Fu | Polymer Donors for High-Performance Non-Fullerene Organic Solar Cells[END_REF][START_REF] Cui | High-performance conjugated polymer donor materials for polymer solar cells with narrow-bandgap nonfullerene acceptors[END_REF] and non-fullerene acceptors. [START_REF] Zhang | Nonfullerene Acceptor Molecules for Bulk Heterojunction Organic Solar Cells[END_REF] While a large variety of promising materials have been reported, morphology control of the BHJ blend at multiple length scales remains another central quest in the field. For instance, at the nanometer scale, the electron donating and accepting materials must be uniformly interfaced over the whole active layer (typically in form of lamella), ideally with each domain size compatible to the exciton diffusion length (10-15 nm), to guarantee that generated excitons reach the donor-acceptor interface within their lifetime prior to radiative and/or nonradiative decays. [START_REF] Shaw | Exciton Diffusion Measurements in Poly(3hexylthiophene)[END_REF] At the molecular scale, the crystal structure of semiconducting compounds must be optimized to get efficient charge carrier transport. Furthermore, morphological instability of the simply-blended BHJ impacts the long-term device performance. The self-assembly of p-conjugated block copolymers is an alternative and promising bottom-up strategy to meet these prerequisites. Among the wealth of conjugated polymers synthesized so far, regioregular poly(3alkylthiophene) (P3AT) have been extensively employed as an electrically active polymer block due to their well-balanced characteristics such as optoelectronic properties, thermal and environmental stability, and synthetic accessibility. [START_REF] Liu | Conducting Block Copolymers of Regioregular Poly(3-hexylthiophene) and Poly(methacrylates): Electronic Materials with Variable Conductivities and Degrees of Interfibrillar Order[END_REF][9][START_REF] Boudouris | Nanoporous Poly(3-alkylthiophene) Thin Films Generated from Block Copolymer Templates[END_REF][START_REF] Grancharov | Stereocomplexed Materials Based on Poly(3-hexylthiophene)-b-poly(lactide) Block Copolymers: Synthesis by Organic Catalysis, Thermal Properties, and Microscopic Morphology[END_REF][START_REF] Lim | Modulating Crystallinity of Poly(3-hexylthiophene) via Microphase Separation of Poly(3-hexylthiophene)-Polyisoprene Block Copolymers[END_REF][START_REF] Kim | Molecular Design of "Graft" Assembly for Ordered Microphase Separation of P3HT-Based Rod-Coil Copolymers[END_REF][START_REF] Dai | Facile Synthesis of Well-Defined Block Copolymers Containing Regioregular Poly(3-hexyl thiophene) via Anionic Macroinitiation Method and Their Self-Assembly Behavior[END_REF][START_REF] Verduzco | Polythiophene-block-polyfluorene and Polythiophene-block-poly(fluorene-cobenzothiadiazole): Insights into the Self-Assembly of All-Conjugated Block Copolymers[END_REF][START_REF] He | All-conjugated poly(3-alkylthiophene) diblock copolymer-based bulk heterojunction solar cells with controlled molecular organization and nanoscale morphology[END_REF] In particular, regioregular poly(3hexylthiophene) (P3HT) has been the working horse of p-type semiconducting polymers. A variety of reports on the P3HT-based block copolymers can be found in the literature, [START_REF] Liu | Conducting Block Copolymers of Regioregular Poly(3-hexylthiophene) and Poly(methacrylates): Electronic Materials with Variable Conductivities and Degrees of Interfibrillar Order[END_REF][9][START_REF] Boudouris | Nanoporous Poly(3-alkylthiophene) Thin Films Generated from Block Copolymer Templates[END_REF][START_REF] Grancharov | Stereocomplexed Materials Based on Poly(3-hexylthiophene)-b-poly(lactide) Block Copolymers: Synthesis by Organic Catalysis, Thermal Properties, and Microscopic Morphology[END_REF][START_REF] Lim | Modulating Crystallinity of Poly(3-hexylthiophene) via Microphase Separation of Poly(3-hexylthiophene)-Polyisoprene Block Copolymers[END_REF][START_REF] Kim | Molecular Design of "Graft" Assembly for Ordered Microphase Separation of P3HT-Based Rod-Coil Copolymers[END_REF][START_REF] Dai | Facile Synthesis of Well-Defined Block Copolymers Containing Regioregular Poly(3-hexyl thiophene) via Anionic Macroinitiation Method and Their Self-Assembly Behavior[END_REF][START_REF] Verduzco | Polythiophene-block-polyfluorene and Polythiophene-block-poly(fluorene-cobenzothiadiazole): Insights into the Self-Assembly of All-Conjugated Block Copolymers[END_REF] but in most cases, strong p-p interactions of P3HT chains dominate over microphase separation. This results in a randomly-oriented nanofibril morphology, [START_REF] Liu | Conducting Block Copolymers of Regioregular Poly(3-hexylthiophene) and Poly(methacrylates): Electronic Materials with Variable Conductivities and Degrees of Interfibrillar Order[END_REF][9][START_REF] Boudouris | Nanoporous Poly(3-alkylthiophene) Thin Films Generated from Block Copolymer Templates[END_REF][START_REF] Grancharov | Stereocomplexed Materials Based on Poly(3-hexylthiophene)-b-poly(lactide) Block Copolymers: Synthesis by Organic Catalysis, Thermal Properties, and Microscopic Morphology[END_REF][START_REF] Lim | Modulating Crystallinity of Poly(3-hexylthiophene) via Microphase Separation of Poly(3-hexylthiophene)-Polyisoprene Block Copolymers[END_REF] which is often found in the P3HT homopolymer, irrespective of the volume fraction of each blocks. In this context, several research groups have attempted chemical modifications of alkyl side chain of P3ATs to weaken the rod-rod interaction between polythiophene backbones. [START_REF] Ho | Tuning Polythiophene Crystallization through Systematic Side Chain Functionalization[END_REF][START_REF] Ho | Poly(3-alkylthiophene) Diblock Copolymers with Ordered Microstructures and Continuous Semiconducting Pathways[END_REF][START_REF] Moon | Self-Assembly of Poly(3-dodecylthiophene)-blockpoly(methyl methacrylate) Copolymers Driven by Competition between Microphase Separation and Crystallization[END_REF][START_REF] Patel | Morphology and Thermodynamic Properties of a Copolymer with an Electronically Conducting Block: Poly(3-ethylhexylthiophene)-block-poly(ethylene oxide)[END_REF][START_REF] Lin | Rational Design of Versatile Self-Assembly Morphology of Rod-Coil Block Copolymer[END_REF] For instance, Segalmen et al. reported the synthesis of poly(3-(2'-ethynyl)-hexylthiophene-block-polylactide (P3EHT-b-PLA) bearing a bulkier branched alkyl side chain and successfully demonstrated various phase-separated structures including lamellae and cylinder depending on the volume fraction of the P3EHT block. [START_REF] Ho | Poly(3-alkylthiophene) Diblock Copolymers with Ordered Microstructures and Continuous Semiconducting Pathways[END_REF] This enriched phase behavior was attributed to the introduction of a branching point in the side chain that results in a decrease of crystallization temperature of P3EHT. Whereas the P3EHT-b-PLA retained a good charge transport property comparable to the P3HT homopolymer, the low thermal stability of the block copolymers (melting point: P3HT (» 220 ºC) >> P3EHT-b-PLA (» 90 ºC)) and less crystalline nature of the P3EHT may be detrimental for OPV applications. In this regard, the use of pristine P3HT as one of the blocks is important to exploit full potential of its characteristics.

With this mind, we have recently reported on the design and synthesis of a new class of carbohydrate-based block copolymer, poly(3-hexylthiophene)-block-peracetylated maltoheptaose (P3HT-b-AcMal7), and demonstrated that the P3HT-b-AcMal7 self-organized into a lamellar structure with a half-pitch of sub-10 nm that corresponds to the exciton diffusion length upon thermal annealing. [START_REF] Sakai-Otsuka | Self-Assembly of Carbohydrate-block-Poly(3-hexylthiophene) Diblock Copolymers into Sub-10 nm Scale Lamellar Structures[END_REF] The carbohydrate block was strategically introduced to impart a strong segregation strength to the block copolymer system, i.e. high Flory-Huggins interaction parameter χ, that arises from their chemical and steric imbalance between two blocks. In addition, the carbohydrate can be a sacrificial block because it can be removed by selective etching with acidic or basic medium. The resulting cavity would be eventually filled with electron acceptors to realize a nanostructured D/A morphology. It is interesting to note that rod-coil block copolymer systems containing π-conjugated polymer block such as the P3HT, the phase behavior is more complex than that of classical coil-coil block copolymer systems. Two additional parameters, the Maier-Saupé interaction (µN) and the conformation asymmetry (e), should be taken into account in addition to the segregation strength parameter (χN) and the volume fraction of the segment. These two additional parameters often affect boundaries of the phase diagram. For instance, Olsen et al. [START_REF] Olsen | Universalization of the Phase Diagram for a Model Rod-Coil Diblock Copolymer[END_REF] investigated self-assembly of a conjugated rod-coil block copolymer (PPV-b-PI) and reported a universal phase diagram for the rod-coil block copolymers. According to the study, lamellar phases occupy a very large region in the phase diagram with a coil fraction up to 0.8, which is considerably a broader range than in classical block copolymers, most likely due to the strong rod-rod interaction.

As will be described below, the value of 0.65 (the volume fraction of the P3HT in the P3HT-b-AcMal7) fits within the range of lamellar phase in this specific rod-coil block copolymer system.

Although our previous work has highlighted the great potential of the P3HT-b-AcMal7, several aspects relative to the copolymer structuring needed further investigations.

Importantly, the crystallinity of constituent semiconducting materials has a significant impact on the device performance because it determines their charge transport properties. [START_REF] Poelking | Effect of Polymorphism, Regioregularity and Paracrystallinity on Charge Transport in Poly(3-hexylthiophene) [P3HT] Nanofibers[END_REF][START_REF] Steyrleuthner | The Role of Regioregularity, Crystallinity, and Chain Orientation on Electron Transport in a High-Mobility n-Type Copolymer[END_REF] The orientation and crystalline structure of the semiconducting segments must be optimized to the practical use and must be controlled simultaneously with phase separation of block copolymers. Such organization is predominantly governed not only by the molecular properties but also by the processing conditions. [START_REF] Zen | Effect of Molecular Weight and Annealing of Poly(3hexylthiophene)s on the Performance of Organic Field-Effect Transistors[END_REF] Hence, the knowledge of the detailed molecular packing of the P3HT block and its variation in the course of post-treatment are important aspects to investigate in order to attain a precisely-controlled model structure.

In this paper, we extend our previous study on self-assembly of carbohydrate-based block copolymers [START_REF] Sakai-Otsuka | Self-Assembly of Carbohydrate-block-Poly(3-hexylthiophene) Diblock Copolymers into Sub-10 nm Scale Lamellar Structures[END_REF] to gain further insight into the internal structure of the self-assembled P3HT-b-AcMal7 and the self-assembly behavior upon thermal treatment. A comprehensive study on the thermally-induced structural evolution of the P3HT-b-AcMal7 was carried out by in situ smalland wide-angle X-ray scattering (SAXS/WAXS) analysis with step-wise heating and cooling. The X-ray scattering were carefully interpreted together with the data from differential scanning calorimetry (DSC) and Fourier-transform infrared spectroscopy (FT-IR).

EXPERIMENTAL SECTION

Materials. Maltoheptaose was purchased from Nagase & Co., Ltd. (Japan) and all other reagents were purchased from Sigma-Aldrich and used as received without further purification unless otherwise specified. Peracetylated azido-functionalized maltoheptaose (AcMal7-N3) was synthesized as previously described. [START_REF] Sakai-Otsuka | Self-Assembly of Carbohydrate-block-Poly(3-hexylthiophene) Diblock Copolymers into Sub-10 nm Scale Lamellar Structures[END_REF] Regioregular alkyne-terminated poly(3-hexylthiophene) (alkyne-P3HT) was prepared by post-functionalization modification of Br/H-terminated P3HT via Stille coupling between Br-terminated polymer end with ethynyltributylstannane. The obtained mono-ethynyl-capped P3HT (SEC: Mw = 6210 g mol -1 , Mn = 5670 g mol -1 , Đ = 1.07; HT-HT regioregularity: > 95 %) was coupled with AcMal7-N3 through copper-catalyzed azide-alkyne cycloaddition (CuAAC "click" reaction) to afford poly (3-hexylthiophene)-b-peracetylated maltoheptaose (P3HT-b-AcMal7) (volume fraction of P3HT: 0.65). The detailed synthetic procedures and characterization of the products are available in the supporting information.

Instruments. [START_REF] Segalman | Block Copolymers for Organic Optoelectronics[END_REF] H (400 MHz) and [START_REF] Kim | Molecular Design of "Graft" Assembly for Ordered Microphase Separation of P3HT-Based Rod-Coil Copolymers[END_REF] C (100 MHz) NMR spectra were recorded using a Bruker Avance DRX 400 MHz. FT-IR spectra were recorded using a Perkin-Elmer Spectrum RXI FT-IR Spectrometer. Size exclusion chromatography (SEC) was performed at 30 °C using an Agilent 390-MDS system (290-LC pump injector, ProStar 510 column oven, 390-MDS refractive index detector) equipped with Knauer Smartline UV detector 2500 and two Agilent PLgel 5µm MIXED-D 300 x 7.5 mm columns (Part No: PL1110-6504) in THF at the flow rate of 1.0 mL min -1 . DSC analysis was performed using a TA Instruments DSC Q200 equipped with RCS 90 cooling unit.

The samples (ca. 5 mg) were firstly dissolved in THF and deposited on the aluminum DSC pan followed by slow evaporation of the solvent. These DSC samples were stored at 100 °C under vacuum for several hours prior to analysis. The measurements were carried out under a nitrogen atmosphere at a scan rate of 10 °C min -1 . AFM phase images were recorded in tapping mode using a Picoplus microscope (Molecular Imaging, Inc., Tempe, AZ). Transmission electron microscopy (TEM) images and electron diffraction (ED) patterns of the spin-coated thin films were recorded using a CM200 Philips microscope (Hillsboro, OR, USA) operating at 200 kV equipped with a TVIPS F216 TemCam camera. The oriented thin films were observed by TEM at 120 kV in bright field (BF) and ED modes using a CM12 Philips microscope equipped with a MVIII (Soft Imaging System) Charge Coupled Device camera. SAXS and WAXS analyses were performed on the BM02 beamline D2AM at the European Synchrotron Radiation Facility (ESRF, Grenoble, France). X-rays of 18 keV (λ = 0.6888 Å) with a spot size of 100 μm were used for all the measurements. Scattering patterns were recorded on two photon-counting pixel detectors (WOS and D5 from imXpad). Power spectra of selected images were calculated using the ImageJ software.

Thin film preparation by mechanical rubbing and structural analysis.

About 30nm-thick films of P3HT-b-AcMal7 were prepared by doctor blading from solutions in chloroform (5 wt % solution) on clean glass substrates. Mechanical rubbing of the copolymer films was performed following the methodology described in previous work. [START_REF] Brinkmann | Molecular Weight Dependence of Chain Packing and Semicrystalline Structure in Oriented Films of Regioregular Poly(3-hexylthiophene) Revealed by High-Resolution Transmission Electron Microscopy[END_REF][START_REF] Tremel | Charge Transport Anisotropy in Highly Oriented Thin Films of the Acceptor Polymer P(NDI2OD-T2)[END_REF][START_REF] Biniek | High-Temperature Rubbing: A Versatile Method to Align π-Conjugated Polymers without Alignment Substrate[END_REF] The rubbing temperature was adjusted between ambient and 200 °C. Two rubbing cycles were used. The alignment of the P3HT blocks was probed by polarized UV-vis absorption spectroscopy using a Cary 5000 spectrometer. Optimal alignment was observed for films rubbed at 190 °C. For TEM analysis, the copolymer films were first coated with an evaporated amorphous carbon film (Edwards Auto 306 evaporator). The samples were recovered from the glass substrate by the polyacrylic acid (PA) (20wt% aqueous solution, Aldrich). In brief, a droplet of PA is deposited on the carbon-coated film and left to dry for 3 hours. The dried PA with the film is stripped off from the glass substrate using a razor blade and deposited on distilled water to dissolve PA. The carboncoated films are then recovered on TEM copper grids.

RESULTS AND DISCUSSION

Synthesis of P3HT-b-Carbohydrate Diblock Copolymer via Modified Synthetic Route and its Self-Assembly in the Solid State. The P3HT-b-AcMal7 diblock copolymer was synthesized in a similar way as described in the previous report except for the preparation of the alkynefunctionalized P3HT block (Figure 1a). [START_REF] Sakai-Otsuka | Self-Assembly of Carbohydrate-block-Poly(3-hexylthiophene) Diblock Copolymers into Sub-10 nm Scale Lamellar Structures[END_REF] In the previous study, an in situ end-functionalization was used to prepare regioregular alkyne-P3HT. [START_REF] Sakai-Otsuka | Self-Assembly of Carbohydrate-block-Poly(3-hexylthiophene) Diblock Copolymers into Sub-10 nm Scale Lamellar Structures[END_REF] However, this method yields P3HTs with a small amount of high molecular weight impurities possibly due to alkyne-alkyne homocoupling between reactive ethynyl-capped P3HTs during the end-capping process. To circumvent these undesirable by-products which may affect the morphology of the self-assembled block copolymer film, an alternative synthetic route based on a post-polymerization modification method was applied. [START_REF] Biniek | High-Temperature Rubbing: A Versatile Method to Align π-Conjugated Polymers without Alignment Substrate[END_REF] The selective ethynyl-functionalization onto the Br-terminal of the stable precursor polymer resulted in a remarkable reduction of the production of dimerized P3HT and a small 1.07 polydispersity index Đ (see Supporting Information Figure S1). All the synthetic details and characterization data are available in the supporting information. The self-assembly behavior of the newly synthesized P3HT-b-AcMal7 showed almost the same trend as the previous one 22 except for the domain size. Both samples self-organized into well-defined lamellar structures upon thermal heating when the block copolymers obtained enough mobility to reach the equilibrium state (Figures 1b andS3). On the one hand, the d-spacing of the new sample estimated from the power spectrum of the TEM images was found to be ca. 12 nm which is slightly smaller than that of the block copolymer synthesized by the previous method (ca. 14 nm) (Figure S3) that had the same molecular weight. The difference in d-spacing was further supported by SAXS analysis, showing the d-spacing of 12.2 nm for the new sample and of 15.4 nm for the previous sample (Figures 1d andS3). This deviation is most likely attributed to the amount of dimerized P3HT in the block copolymer sample (Table S2). The ED pattern of the new sample indicates that the P3HT segments form crystalline domains by showing a diffraction ring attributable to the p-p stacking of the P3HT backbone corresponding to a spacing of ca. 0.38 nm (Figure 1c). monolayer packing with non-interdigitated AcMal7 segments, (b) monolayer packing with interdigitated AcMal7 segments, (c) a bilayer structure with a tail-to-tail packing of P3HT blocks and non-interdigitated AcMal7 segments. According to the SAXS measurements, the phase separation of the P3HT-b-AcMal7 results in a 12.2 nm d-spacing of the lamellar structure. On the other hand, the d-spacing calculated from a broad primary scattering peak of the alkyne-P3HT homopolymer was found to be 10.7 nm, which is consistent with the average width of the P3HT nanofibers (Figure S4). Twice the length of the extended P3HT blocks in tail-to-tail configuration (c) amounts to 21.4 nm that exceeds largely the observed periodicity of 12.2 nm. Therefore, we can rule out the bilayer packing of the copolymer (c). Only the packing schemes (a) and (b) are a priori possible and will be discussed hereafter. Since the P3HT and AcMal7 blocks are tethered, they must share the same lateral arrangement.

The cross-sectional areas (A) of the P3HT and AcMal7 segments, which deservedly have an impact on the molecular conformation especially at the interface of the two blocks, were therefore estimated on the basis of the unit cell parameters (a, b, and γ) according to the following equation:

A = absin(g)/n ( 1
)
where n is the number of chains per unit cell. Since the peracetylated maltoheptaose does not contain enough glucose units, it does not form periodic helical structures observed for many other polysaccharides but may have an amorphous structure. Thus, alternatively, the unit cell parameters of amylose triacetate (form I) which has exactly the same chemical structure as AcMal7, i.e.

peracetylated linear α-1,4 linked D-glucan was used for the calculation. [START_REF] Takahashi | Crystal Structure of Amylose Triacetate I[END_REF] We suppose that this crystal structure is the most compact one for AcMal7 in the solid state. The calculated crosssectional areas of the P3HT (AP3HT) and AcMal7 (AAcMal7) are 0.62 and 1.03 nm 2 , respectively (Table 1). The AAcMal7 is found to be 1.7 times larger than the AP3HT. Considering the fact that a diffraction ring attributable to the π-stacking of the thiophene backbone (ca. 0.38 nm) has been observed in the ED pattern of the phase-separated P3HT-b-AcMal7 thin film (Figure 1c), the P3HT segments should have a crystalline structure closely similar to the unit cell reported for form I. [START_REF] Kayunkid | Structural Model of Regioregular Poly(3hexylthiophene) Obtained by Electron Diffraction Analysis[END_REF] In this case, the AcMal7 segments cannot interdigitate each other due to their large molecular dimension compared with that of the P3HT segments. Therefore, the side-by-side arrangement (Figure 2a) seems the most likely model. 13

Non-polar molecules tend to fill the space avoiding free volumes, to reduce the enthalpy. Now suppose that the AcMal7 segments first form a stable structure analogous to the crystal structure of the model compound of amylose triacetate. If the P3HT segments are aligned parallel to the AcMal7 segment without tilt as shown Figure 3a, the π-π stacking distance of the P3HT backbone would be determined by intermolecular distance of AcMal7 of 1.09 nm because of the bulky structure of the AcMal7. In this case, the predicted density of the P3HT segment for this arrangement (ρP3HT, EX = 0.77 g cm -3 ) is considerably lower than that of the crystal (ρP3HT, crystal = 1.14 g cm -3 ), [START_REF] Takahashi | Crystal Structure of Amylose Triacetate I[END_REF] indicating that the non-tilted P3HT arrangement is thermodynamically unfavorable.

In order to maintain the crystal density, the P3HT should be stacked with a stacking period of 0.78 nm per two chains equivalent to the lattice parameter b. Hence, the tilting of the P3HT main chain is the only solution compatible with a thermodynamically stable packing. The structure in consideration of the consistency with the crystal density is presented in Figure 3b. The tilt angle based on this model can be estimated as follows:

q » arccos (0.78 nm/1.09 nm) » 44° To further assess the tilt arrangement based on space-filling arguments, additional ED measurements were performed on a highly oriented P3HT-b-AcMal7 film. A uniform alignment of the lamellar structure over large area was achieved by high-temperature rubbing and allowed for a precise evaluation of the tilt angle of the P3HT backbone with respect to the lamellar plane.

Rubbing is particularly effective to prepare alignment layers in the field of display technology [START_REF] Toney | Nearsurface alignment of polymers in rubbed films[END_REF] and to orient semiconducting polymers such as P3HT. [START_REF] Tremel | Charge Transport Anisotropy in Highly Oriented Thin Films of the Acceptor Polymer P(NDI2OD-T2)[END_REF][START_REF] Biniek | High-Temperature Rubbing: A Versatile Method to Align π-Conjugated Polymers without Alignment Substrate[END_REF][START_REF] Hartmann | 2D Versus 3D Crystalline Order in Thin Films of Regioregular Poly(3hexylthiophene) Oriented by Mechanical Rubbing and Epitaxy[END_REF] It is also noteworthy that for a homopolymer of equivalent Mn, cP3HT//R, indicating that the ±33° tilt is a consequence of the presence of the AcMal7 block.

From the above-mentioned considerations and experimental evidence obtained by ED, it can be concluded that the P3HT and AcMal7 segments are confined in the lamellae in which the AcMal7 Figure 5a shows DSC heating traces of the P3HT-b-AcMal7 and alkyne-P3HT samples crystallized at a slow 2 °C min -1 cooling rate. As seen in the previous study, [START_REF] Sakai-Otsuka | Self-Assembly of Carbohydrate-block-Poly(3-hexylthiophene) Diblock Copolymers into Sub-10 nm Scale Lamellar Structures[END_REF] an endothermic peak associated with the melting process of P3HT crystal of the P3HT-b-AcMal7 was observed at higher temperature (Tm = 194 °C) than that of the P3HT homopolymer (Tm = 188 °C). The relation of the corrected melting enthalpy DHm,P3HT for the respective polymers coincides with the order of Tm, P3HT-b-AcMal7 (18.9 J g -1 ) > alkyne-P3HT (15.5 J g -1 ). Note that the DHm,P3HT were determined by integration of melting peak area followed by normalization by the weight fraction of P3HT in the sample to give the amount of heat per P3HT unit weight. These trends in the Tm and DHm,P3HT

indicate an enhanced stability of the crystalline P3HT domain confined in the phase-separated P3HT-b-AcMal7 whereas the Tm and DHm of many other phase-segregated rod-coil block copolymers were often reported lower than those of the constituent crystalline homopolymer due to a detrimental effect of non-crystalline coil-block on the crystalline perfection. [START_REF] Lim | Modulating Crystallinity of Poly(3-hexylthiophene) via Microphase Separation of Poly(3-hexylthiophene)-Polyisoprene Block Copolymers[END_REF][START_REF] Lee | Self-assembly and phase transformations of π-conjugated block copolymers that bend and twist: from rigid-rod nanowires to highly curvaceous gyroids[END_REF][START_REF] Lee | Morphology, and Field-Effect Transistor Characteristics of Crystalline Diblock Copolymers Consisted of Poly(3hexylthiophene) and Syndiotactic Polypropylene[END_REF] This observation is further supported by temperature-dependent in situ FT-IR spectroscopy. According to the preceding study, the absorption bands in the 850-790 cm -1 region are susceptible to the outof-plane bending mode of the Cb-H (see Figure 5d; related atoms are indicated in blue) on the thiophene ring (d(Cb-H)). Particularly, the characteristic bands at 820 and 833 cm -1 have been respectively assigned to the d(Cb-H) in the crystalline and in the amorphous phases. [START_REF] Yazawa | Dynamic Structure of Regioregulated Poly(alkylthiophene)S[END_REF] Thus, both bands were used to monitor the crystalline state of the P3HT segment of the block copolymer. The whole absorption spectrum of the P3HT-b-AcMal7 (4000-450 cm -1 ) recorded at room temperature and the assignments of the characteristic bands are available in the Supporting Information (Figure S6 and Table S4). Figures 5b and5c show variations of FT-IR absorption spectra of the P3HT-b-AcMal7 in the 850-790 cm -1 region during heating and cooling process, respectively. In the heating cycle, the band located at 820 cm -1 decreases in intensity while the band at 833 cm -1 becomes dominant. At 195 °C, the peak at 820 cm -1 completely disappeared, meaning that the P3HT segments are in the amorphous phase. In the cooling cycle, a reverse phase transition from amorphous to crystal is observed. A similar spectral change was observed in the P3HT homopolymer except that the temperature ranges where the phase transitions occurred were lower (Figure S7). In Figure 5e, the intensities at 820 cm -1 (A820) are plotted as a function of increasing temperature to better visualize the structural change. With increasing temperature, an abrupt decrease of A820 is observed for both samples. However, the crystalline-to-amorphous phase transition of the homopolymer begins/completes at a temperature about 5 °C lower than that of the P3HT-b-AcMal7. These results provide another evidence to confirm the higher thermal stability of the P3HT crystalline structure in the P3HT-b-AcMal7 organization.

b) Effect of Crystallization Rate on the Melt Behavior of P3HT-b-AcMal7

Figures 6a and6b show the DSC thermograms of P3HT-b-AcMal7 and alkyne-P3HT, respectively.

The thermograms correspond to the heating cycles (heating rate of 10 °C min -1 ) recorded after a cooling process from 220 to 0 °C. The cooling was realized at different cooling rates in the range 2-30 °C min -1 . The melting enthalpy based on the total sample weight (DHm, total,) and corrected melting enthalpy (DHm, P3HT) were determined from each thermograms. The detailed data are summarized in the Table S5. For all heating traces of the P3HT homopolymer, a single endothermic peak corresponding to the Tm of the P3HT segment was observed. The value of Tm is insensitive to the cooling rate. On the other hand, in a series of heating traces of the P3HT-b-AcMal7, an obvious change in the melting behavior was found depending on the cooling rate. In the first heating run and second heating run after underwent the slow crystallization (cooling rate of 2 °C min -1 ), a single endothermic peak was observed around 193-194 °C. When the sample was crystallized at a higher cooling rate, an additional endothermic peak appeared in the heating scans.

For example, for a cooling rate of 10 °C min -1 , two melting peaks were observed at 190 and 198 °C.

With the increase of the cooling rate, the former peak was shifted to lower temperature from 190 to 186 °C, whereas the later peak remained at the same position. This observation implies that there are at least two crystalline states which are formed through different crystallization process, i.e. the lower-T peak corresponds to the crystallization governed by kinetic factor and the higher-T peak corresponds to the crystallization governed by thermodynamic factor. If the crystallization rate is fast enough, the crystallization behavior may be governed by thermodynamic factor and is not susceptible to the cooling rate. On the contrary, if the crystallization rate is very slow, with increasing cooling rate, kinetic factor becomes dominant and it results in less ordered semicrystalline structures because of an insufficient time to crystallize into thermodynamically stable equilibrium structure. Therefore, it is reasonable to assume that the crystallization of the P3HT-b-AcMal7 system takes place via two processes: slow and fast crystallization. The existence of these multi-crystallization processes might reflect the different environments for the P3HT segment in the P3HT-b-AcMal7 melt, i.e., chain-end tethered with AcMal7 (low mobility, modest steric hindrance), middle part (highly crystalline part), and free chain-end (high mobility), etc. by Small-angle X-ray Scattering Analysis. To investigate the temperature dependence of the micro-phase separation in detail, an in situ SAXS analysis during the heating and cooling was performed on the bulk sample of the P3HT-b-AcMal7 (Figures 7a and7b). The bulk samples were stepwise heated from room temperature to 230 °C with an interval of 10 °C and then cooled below 100 °C by simple heat dissipation. As shown in Figure 7a, the SAXS profiles below 120 °C show no clear diffraction compared to the central scattering. At 130 °C, two peaks originated from the micro-phase separation (indexed as q* and 2q*) appeared in a q-range between 0.04 and 0.13 Å -1 and progressively become intense and sharper as the temperature increases. Then, above 188 °C, a drastic sharpening of the q* and 2q* peaks is observed. These sharply-defined peaks are sustained in the initial stage of cooling process between 210 to 180 °C, then become broader. At the same time, a broad peak indexed as the 100 reflection, corresponding to the interlayer distance separated by the hexyl side chain, is also observed in a higher q-range. As the temperature increases, the 100 peak became sharper and shifted toward lower q region. The shift is due to thermal expansion of the hexyl side chains, and the sharpening reflects an increasing long-range order. The same thermal behavior is found for the 100 reflection of the P3HT homopolymer expect for the fact that the 100 peak of homopolymer vanishes at 200 °C (Figure S8) whereas that of the block copolymer remains up to 220 °C. Again, this indicates that a higher temperature is required to melt the P3HT crystalline structure when AcMal7 is attached to the P3HT segment. In the cooling processes from the molten state, 100 reflection peak of the P3HT-b-AcMal7 and the homopolymer appear again at 180 and 150 °C, respectively. Upon further cooling, the 100 peak shifts back toward its original position while the peak broadens. The broadening of the 100 peak during the cooling is counterintuitive but the shrinking of the hexyl groups might have introduced internal strain. The detailed discussion about the crystal structure of the P3HT segment will be described later sub-section.

Herein, it is interesting to observe that the P3HT-b-AcMal7 system displays well-ordered lamellar structure in the molten state, which can be assimilated to liquid crystals or phase separation of flexible polymers. This is a direct evidence that the P3HT-b-AcMal7 possesses a strong segregation strength (χN) between P3HT and AcMal7 segments. In the crystalline-rubber block copolymer system whose Tc is in between the order-disorder temperature (TODT) and Tg (TODT > Tc > Tg), crystallization precedes solidification of rubber block upon cooling. Hence, when the segregation strength between crystalline and rubber blocks is not sufficiently high, microphase-separated structure formed in the molten state will be destroyed due to the strong crystallization tendency of the crystalline block. [START_REF] He | Crystallization assisted self-assembly of semicrystalline block copolymers[END_REF] In strong contrast, we observe that the crystallization of the P3HT segments of P3HT-b-AcMal7 takes place within the phase-separated nanodomains of the lamellar phase, indicating that P3HT and AcMal7 are strongly segregated throughout the whole structure formation process.

The variation of d-spacing of the lamellar structure calculated from the q* peak position is shown in Figure 7c. Throughout the entire process, three obvious transitions, that can be linked to the thermal properties of the two blocks, are observed. Firstly, in the vicinity of the glass transition of the AcMal7 (Tg, AcMal7, offset = 120 °C), a characteristic peak q* appeared. With the temperature increases up to 175 °C, the corresponding d-spacing gradually increases from 11.7 to 12.6 nm. As evidenced by DSC and temperature-dependent FT-IR measurements, in this temperature range, the AcMal7 and P3HT segments gain mobility and exhibited the structural change. Hence, it is reasonable to assume that the block copolymer experienced a rearrangement as a consequence of relaxations of the AcMal7 and P3HT segments from the collapsed state which was initially induced by rapid solvent evaporation during sample preparation. Secondly, above 175 °C where the P3HT block is partially molten, i.e. above the onset temperature of the melting area (Tm, P3HT-b-AcMal7, onset), the d-spacing shows a sudden downward trend due to a shrinkage of the P3HT in molten state and can be at least attributed to decreasing segregation strength. Thirdly, in the cooling cycle, the dspacing increases monotonically in the temperature range between 220 and 150 °C where the P3HT segment is in a molten state (above Tc,P3HT-b-AcMal7, onset) but the segment becomes more extended up to the fully extended state in the crystals. After the P3HT segment is crystallized, the d-spacing shows a small declining trend with the temperature decrease probably due to the thermal contraction of the existing lamellae. It is worth noting that in the cooling process, a linear dependence of d-spacing versus 1/T was always reported for the coil-coil block copolymer melts under the TODT. [START_REF] Sakamoto | Order-Disorder Transition of Low Molecular Weight Polystyrene-block-Polyisoprene. 1. SAXS Analysis of Two Characteristic Temperatures[END_REF] In our rod-coil system, the shrinkage in d-spacing with reduced temperature during the cooling process below 150 °C was observed. This could be caused by the more compact π-π stacking of crystallized P3HT segments under lower temperatures. Similar conclusion, the increased packing density of P3HT segments under a reduced temperature, was also reported in simulation study. 40 8a shows the diffraction pattern of as-prepared bulk sample of the P3HT-b-AcMal7. Three distinct diffraction peaks are observed in the q-range from 0.6 to 2.1 Å -1 . These peaks are found in the vicinity of the reflection positions of the P3HT estimated based on the reported unit cell, [START_REF] Kayunkid | Structural Model of Regioregular Poly(3hexylthiophene) Obtained by Electron Diffraction Analysis[END_REF] indicating that the P3HT synthesized in this study have a similar crystal structure to the reported unit cell of form I.

Two intense reflections located below 1.20 Å -1 can be indexed as 200 and 300 (periodicity along the hexyl side chain direction). The intense peak at 1.64 Å -1 arises from the overlap of the 020 and 002 reflections and is dominated by the intense 020 (p-p stacking periodicity). After thermal annealing, the entire diffraction peaks became sharper and the peak positions shifted (red profile in Figure 8a). In other words, thermal annealing leads to not only larger apparent crystallite sizes but also changes the crystal lattice. Taking a close look at the change, the h00 reflections shifted toward lower q after thermal treatment. To be specific, the d-spacing of 200 peak increased from 8.02 to 8.50 Å upon annealing, which corresponds to an expansion by 6% along the alkyl side chain direction. On the other hand, a broad reflection peak 020 centered at q = 1.64 Å -1 shifted to a higher q-range region at around q = 1.67 Å -1 . This reflects a shrinking of the lattice spacing from 3.83 to 3.77 Å that is equivalent to a reduction in size by 1.6 %. The similar structural changes of the P3HT homopolymer induced by temperature were reported by Pietsch 41 and Grigorian. [START_REF] Joshi | Bimodal Temperature Behavior of Structure and Mobility in High Molecular Weight P3HT Thin Films[END_REF][START_REF] Grigorian | Temperature-dependent structural properties of P3HT films[END_REF] For a monoclinic system, this reduction can be due to either (i) shrinking of c-axis (i.e. chain shrinkage),

(ii) reduction in the π-stacking distance (i.e. shortening of the b-axis) or (iii) change in the monoclinic angle. Since the backbone is quite rigid, and no explanation can be found to reduce the π-stacking distance with increased temperature, scenario (iii) seems to be the most probable.

Molecularly it represents a shift between layers composed of π-stacked chains that can be induced by the change in the tilt angle of hexyl groups. In any case, the P3HT segment in the block copolymer experienced a structural transition from the crystal structure analogous to that of P3HT unit cell to thermodynamically more stable structure by adopting its crystal conformation to the phase-separated nano-domain in the course of thermal treatment.

Figure 8b

presents the evolution of WAXS profiles during the heating process of the P3HT-b-AcMal7. With the temperature increase up to 120 °C, the 020 peak slightly shifts toward higher qrange, which is opposite to the shift of h00 peaks, then shifts back to lower q by further heating above 120 °C. Figures 8c and8d show a variation of the d-spacing calculated from the peak position of 200 reflection (d200) and one calculated from the peak position of 020 reflection (d020), respectively, together with the first temperature derivatives of the corresponding d-spacing. The d200 follows a similar trend as d100 what is seen in Figure 7a, with a slow transition between 60 and 110 °C superimposed with a linear thermal expansion coefficient of about 800 ppm K -1 . The transition is accompanied by about 6 % increase in d200. The d020 also shows a similar trend with a thermal expansion coefficient of 100 ppm K -1 and the transition between 60 and 110 °C which induces a decrease of d-spacing of about 1 %. The first derivatives of d200 showed a close similarity in shape to that of d020 but with opposite sign, supporting the phase transition occurring between 60 and 110 °C.

The in-situ WAXS experiment revealed the difference between the annealed and as cast samples of P3HT-b-AcMal7 comes from the phase transition occurring between 60 and 110 °C during the first heating, where the basic arrangement of P3HT segment slightly changes. This phase transition was not accompanied by a change in internal energy as no heat-flow could be detected in the DSC thermogram. If the d100 increased by 6 % and d020 shrank by 1 % during the phase transition, the net density of P3HT segments decreased which should lead to an increase in internal energy. This might have been compensated by the densification and rearrangement of AcMal7 segment, which was not detectable by diffraction due to its amorphous nature. In the solution casting, the P3HT segment starts to crystallize prior to complete evaporation of the THF solvent, and the structure formation might be dictated by the crystallization tendency of P3HT leading the AcMal7 in high-energy packing situation. In the complete absence of solvent, the thermal annealing would soften the P3HT segments, allowing the AcMal7 segment to relax, imposing some constraint on P3HT that converts into another crystalline form. The net enthalpy would be almost zero as the conversion is simply a transfer of internal energy from AcMal7 segments to P3HT segments. (ii) stable crystal formed under the control of thermodynamic factors. The origin of such a behavior can be attributed to the tethering of P3HT with AcMal7 which leads to the different chemical and geometrical environments for the P3HT segments (weakly mobile chain-end anchored by AcMal7, highly crystallizable middle part, and highly mobile free chain-end). Thus, the crystallization of the P3HT segment occurs in the confined space of the lamellar phase where the contribution of tethering effect cannot be avoided. While this study focused on the specific case of P3HT-b-AcMal7, we believe that our results provided new insights into the temperature-dependent selfassembly behavior of the P3HT confined in a phase-separated lamellar structure and hope that it

Materials

Maltoheptaose was purchased from Nagase & Co. Ltd. (Japan) and all other reagents were purchased from Sigma-Aldrich and used as received without further purification unless otherwise noted. THF was refluxed and distilled from sodium benzophenone ketyl prior to use to ensure water, oxygen, and peroxide-free state. Lithium chloride (LiCl) was dried in vacuo at 140 °C before use. 2, 5-Dibromo-3-hexylthiophene, 1-hexene, and triethylamine were stirred overnight over CaH2 and distilled prior to use.

Synthesis of Br/H-terminated P3HT

The Br/H-terminated P3HT was synthesized by well-established reported procedure. In a dry 100 mL Schlenk flask, LiCl (1.23 g, 29.1 mmol, 26 equiv.) was introduced and dissolved in freshly distilled dry THF (56 mL). The solution was stirred at room temperature until LiCl was completely dissolved. Then 2, 5-dibromo-3-hexylthiophene (6.0 mL, 28.0 mmol, 25 equiv.) and tertbutylmagnesium chloride (13.5 mL, 2.7 mmol, 24 equiv.) were transferred to the flask via syringe under an argon atmosphere and stirred at room temperature overnight in order to complete the metal-halogen exchange reaction. In another dry 500 mL Schlenk flask, Ni (dppp) Cl2 (0.59 g, 1.1 mmol, 1 equiv.) was added and flame dried, and then 200 mL of dry THF was added. The activated Grignard monomer solution was transferred into a 500 mL Schlenk flask using a cannula and stirred for 30 min at room temperature. 5N HCl was added to the reaction mixture to quench the reaction, and the mixture was stirred for 30 min and then poured into cold methanol. The precipitate was fractionated by successive Soxhlet extraction by using MeOH, Hexane, and DCM.

DCM fraction was collected for subsequent reaction. After removal of the solvent, the product was re-solved in THF and precipitated into cold MeOH and dried under reduced pressure to afford Br/H-capped P3HT as a purple solid (yield: 59 %).

Stepwise Heating and Cooling FT-IR Measurements

The samples for in situ FT-IR study on the structural evolution were prepared by drop-casting of the polymers onto a ZnSe window and set on a Pike Technologies heated solid transmission accessory. The sample was heated from room temperature to 210 °C and held at the target temperature for 3 min. The spectra were then recorded at a 2 cm -1 resolution with 4 scans. All processes were performed under a nitrogen flow. The obtained spectra were normalized to the absorption band at 2922 cm -1 corresponding to the CH2 asymmetric stretching vibration of the hexyl side chain, vas(CH2).

SAXS and WAXS Measurements

All samples for SAXS and WAXS measurements were prepared by drop-casting from concentrated polymer solutions onto a PTFE substrate. THF or chloroform was used as a solvent.

The polymer solutions were filtered through a 0.45 µm PTFE filter prior to deposit. After complete evaporation of the solvent, about 10 µm-thick films were treated under optional annealing conditions. The bulk samples were then peeled off from the substrate and finely crashed to put into glass capillaries with a diameter of 1.5 mm. The capillaries were sealed with hot-melt adhesive.

The experiments were performed on the BM02 beamline D2AM at the European Synchrotron Radiation Facility (ESRF, Grenoble, France). X-rays of 18 keV (λ = 0.6888 Å) with a spot size of 100 μm were used for all the measurements. Scattering patterns were recorded on two photoncounting pixel detectors (WOS and D5 from imXpad). In case of the stepwise heating and cooling experiments, the samples were heated from room temperature to 230 °C with an interval of 5 or 10 °C using a thermal controller and cooled by simple heat dissipation.

Figure S1.

Comparison of the SEC traces of the alkyne-P3HT used in this study which was synthesized via postpolymerization functionalization method (solid line) and the one previously synthesized by in situ functionalization method (dotted line). S1) and (b) P3HT-b-AcMal7 (entry 2 in Table S1) thin films obtained after thermal annealing at 220 °C for 10 min. Insets represent fast Fourier transform (FFT) images. Scale bars indicate 200 nm. SAXS profiles of (c) P3HT-b-AcMal7 (entry 1 in Table S1) and (d) P3HT-b-AcMal7 (entry 2 in Table S1) bulk samples obtained after thermal annealing at 220 °C for 10 min. Table S3. Experimental structural parameters for P3HT-b-AcMal7 and alkyne-P3HT.

Figure 1 .

 1 Figure 1. (a) Synthetic route of P3HT-b-AcMal7 diblock copolymer. (b) TEM image of the P3HTb-AcMal7 thin film obtained after thermal annealing at 220 °C for 10 min. Scale bar indicates 100 nm. Inset: Power spectrum of the image. (c) Electron diffraction pattern of the phase-separated P3HT-b-AcMal7 thin film showing a diffraction ring corresponding to the p-p stacking of the P3HT backbone with 0.38 nm. (d) SAXS profile of the P3HT-b-AcMal7 bulk sample after thermal annealing at 220 °C for 10 min.

Figure 2 .

 2 Figure 2. Schematic images of possible packing models for lamellar structure of the P3HT-b-AcMal7, where orange and red bars represent the P3HT and AcMal7 segments, respectively. (a) monolayer, non-interdigitated AcMal7 packing (side-by-side arrangement), (b) monolayer, interdigitated AcMal7 packing, and (c) bilayer, non-interdigitated AcMal7 packing. For simplicity, scale and tilt of each block are disregarded here.

Figure 3 .

 3 Figure 3. Schematic illustrations of (a) hypothetical arrangement and density assuming P3HT segments are aligned parallel to the AcMal7 segments, and (b) expected arrangement estimated based on space-filling density argument. Orange and red lines represent the P3HT and AcMal7 segments, respectively.

  Rubbing P3HT-b-AcMal7 at 190 °C afforded a highly oriented lamellar structure as shown in Figure 4a. The TEM image of the rubbed film reveals a preferential perpendicular alignment of the lamellar structure to the rubbing direction. A 12.5 nm lamellar periodicity was estimated from the FFT of the TEM image. It is identical to that measured for the annealed thin films prepared by spin-coating. The ED pattern of the rubbed film is shown in Figure 4b. The absence of the (h00)P3HT reflections implies no "face-on" orientation, i.e. hexyl side chains of the P3HT align exclusively perpendicular to the substrate. The 020P3HT reflection representing the p-stacking of the P3HT is observed with intense arcs at ± 57° relative to the rubbing direction. The presence of the anisotropic intensity in the Scherrer ring forthrightly indicates ± 33° tilting of the P3HT backbones with respect to the lamellar plane as illustrated in Figure 4c. This tilt between the rubbing direction R and the chain direction is further in agreement with the low values of the dichroic ratio measured by polarized UV-vis spectroscopy.

  segments are aligned side-by-side (no interdigitation). The P3HT segments are tilted about 33-44° with respect to the lamellae plane and strongly π-stacked with an extended chain conformation in order to attain thermodynamically stable crystalline structure. An overall view of the proposed molecular packing model for lamellar structure of P3HT-b-AcMal7 is depicted in Figure S5.

Figure 4 .

 4 Figure 4. (a) TEM image of highly-oriented P3HT-b-AcMal7 film prepared by high-temperature

Figure 5 .

 5 Figure 5. (a) DSC thermograms of P3HT-b-AcMal7 (red) and alkyne-P3HT (black) recorded during heating cycle with a heating rate of 10 °C min -1 after cooling with a cooling rate of 2 °C min -1 . Variation of FT-IR absorption spectra of P3HT-b-AcMal7 in the region of Cb-H out-of-plane deformation associated with p-stacking mode of thiophene rings during (b) heating and (c) cooling process. (d) Chemical structure of P3HT. The atoms related to the Cb-H out-of-plane bending mode are indicated in blue. (e) Absorption intensity at 820 cm -1 of the corresponding FT-IR spectra of P3HT-b-AcMal7 (red) and P3HT (black) during the heating process as a function of temperature.

Figure 6 .

 6 Figure 6. DSC thermograms of (a) P3HT-b-AcMal7 and (b) alkyne-P3HT recorded during heating cycles with a heating rate of 10 °C min -1 after cooling cycle with different cooling rate.

Figure 7 .

 7 Figure 7. SAXS profiles of P3HT-b-AcMal7 bulk sample taken during in situ (a) heating process from 30 to 230 °C and (b) cooling process from 220 to 30 °C. (c) Temperature dependence of the d-spacing of P3HT-b-AcMal7 lamellae during in situ measurement. (d) Schematic illustration of possible conformational changes over thermal processing, where orange and red lines represent P3HT and AcMal7 segments, respectively. The relative size of each block is disregarded here.

Figure 8 .

 8 Figure 8. (a) Comparison of WAXS profiles of as-prepared (black) and thermally-annealed (red) bulk P3HT-b-AcMal7 sample. Inset is the widely-accepted unit cell of the P3HT crystal. Reflection positions estimated based on the unit cell are plotted with purple marks in the graph. (b) WAXS profiles of P3HT-b-AcMal7 bulk sample during in situ heating process from 30 to 200 °C. Variation of (c) d200 and (d) d020 as a function of temperature. Black dotted lines in (c) and (d) indicate first derivatives of d200 and d020, respectively.

aFigure S2. 1 H

 1 Figure S2. 1 H NMR spectra of (a) Br/H-capped P3HT and (b) alkyne-P3HT in CDCl 3 .

Figure S3 .

 S3 Figure S3. TEM images of (a) P3HT-b-AcMal7 (entry 1 in TableS1) and (b) P3HT-b-AcMal7 (entry 2 in TableS1) thin films obtained after thermal annealing at 220 °C for 10 min. Insets represent fast Fourier transform (FFT) images. Scale bars indicate 200 nm. SAXS profiles of (c) P3HT-b-AcMal7 (entry 1 in TableS1) and (d) P3HT-b-AcMal7 (entry 2 in TableS1) bulk samples obtained after thermal annealing at 220 °C for 10 min.

  a d -spacing determined by Fast Fourier transform(FFT) of TEM image. b d -spacing determined from primary scattering peak q * in the corresponding SAXS profiles. c Head-to-tail (HT) coupling regioregularity determined by[START_REF] Segalman | Block Copolymers for Organic Optoelectronics[END_REF] H NMR. d The amount of bi-ethynyl-functionalized P3HT determined by MALDI-TOF MS. e Polydispersity (Đ ) determined by SEC in THF based on PS standards.

Figure S4 .

 S4 Figure S4. (a) AFM phase image of as cast film of alkyne-P3HT. Scale bars indicate 100 nm (b) SAXS profile of as prepared alkyne-P3HT bulk sample.

Figure S5 .

 S5 Figure S5. Overall view of the proposed molecular packing model of P3HT-b-AcMal7 lamellar structure, where orange bar, blue and red line represent the P3HT backbone, hexyl side-chain of P3HT, and AcMal7, respectively.

Figure S6 .

 S6 Figure S6. FT-IR absorbance spectra of the P3HT-b-AcMal7 recorded at room temperature.

a

  Peak code are shown in FigureS6.

Figure S7 .

 S7 Figure S7. Variation of FT-IR absorption spectra of alkyne-P3HT in the region of Cb-H out-of-plane deformation associated with p-stacking mode of thiophene rings during whole heating and cooling process.

Figure S8 .

 S8 Figure S8. SAXS profiles of alkyne-P3HT bulk sample in a q-range between 0.25 and 0.36 Å -1 taken during in situ heating and cooling process

Table 1

 1 Structural parameters of P3HT and AcMal7

	P3HT	AcMal7

a Unit cell parameters and density for P3HT and AcMal7 were referred from ref.

32 and ref. 31, respectively.

Table S1 .

 S1 Characterization details of the synthesized carbohydrate-conjugated block copolymers

	1	P3HT-b -AcMal 7	post-polymerization functionalization	5670	6210	3682	1.07	0.65
	2	P3HT-b -AcMal 7	in situ functionalization	5330	6870	3596	1.35	0.64

Table S2 .

 S2 Comparison of two P3HT-b-AcMal7 systems synthesized by different methods.

				Entry 1:	Entry 2:
				P3HT-b -AcMal 7 (this study)	P3HT-b -AcMal 7 (previous study)
	d -spacing
	FFT of TEM image a		ca . 12 nm	ca . 14 nm
	SAXS	b		12.2 nm	15.4 nm
	characteristics of P3HT block
	end-functionalization method	post-polymarization functionalization	in situ functionalization
	HT coupled regioregularity	c	> 94 %	> 95 %
	bi-ethynyl-functionalized P3HT d	0 %	7 %
	dimerized P3HT		poor	rich
	Đ P3HT e		1.07	1.35

Table S4 .

 S4 Assignments of FT-IR absorption bands for P3HT-b-AcMal7

		wavenumber
		(cm -1 )
	1	3054	thiophene ring (P3HT) C β -H out-of-plane streching
	2	2955	hexyl chain (P3HT)	CH 3 asymmetric streching
	3	2926	hexyl chain (P3HT)	CH 2 asymmetric streching
	4	2856	hexyl chain (P3HT)	CH 2 symmetric streching
	5	1753	carbonyl (AcMal 7 )	C=O streching
	6	1510	thiophene ring (P3HT) C 2 =C 3 , C 4 =C 5 symmetric streching
	7	1456	thiophene ring (P3HT) C 2 =C 3 , C 4 =C 5 asymmetric streching
	8	1371	acetyl group (AcMal 7 ) C-H (CH 3 ) bending
			hexyl chain (P3HT)	C-H (CH 3 ) bending
	9	1237	acetyl (AcMal 7 )	C-O streching
	10	833	thiophene ring (P3HT) C β -H bending in amorphous phase

Table S5 .

 S5 Thermal properties of P3HT-b-AcMal 7 and alkyne-P3HT obtained by DSC analysis

				heating cycle
	sample	cooling rate (°C min -1 )	1st peak 2nd peak ΔH m, total a ΔH m, P3HT T m (°C) ΔH m (J g -1 )	b
	P3HT-b -AcMal 7 as prepared	193	-	-	-
		2	194	-	12.3	18.9
		10	190	198	11.8	18.1
		20	188	198	11.9	18.2
		30	186	197	11.4	17.5
	alkyne-P3HT	as prepared	187	-	-	-
		2	188	-	15.5	15.5
		10	186	-	14.1	14.1
		20	185	-	13.9	13.9
		30	185	-	12.9	12.9

a The experimental values of total melting entharpy.

b Corrected values based on the P3HT weight fraction.

the BM02 beamline at ESRF was funded by Agence Nationale de la Recherche (ANR, France) under the "Investissements d'Avenir" program (grant number #ANR-11-EQPX-0010). We thank Isabelle Morfin for her technical assistance during the experiments at ESRF. Marc Schmutz and Christian Blanck (TEM platform at ICS) are gratefully acknowledged for technical support in TEM.

will be a guide to the better control of hierarchical structures and the more rational design toward the high-preforming semiconducting block copolymer systems.

AUTHOR INFORMATION

Corresponding Author

Redouane Borsali -Univ Grenoble Alpes, CERMAV, CNRS, F-38000 Grenoble, France; ORCID: https://orcid.org/0000-0002-7245-586X Email: borsali@cermav.cnrs.fr

NOTES

The authors declare no competing financial interest.

Supporting Information

Competing Molecular Packing of Blocks in Lamella-forming

Carbohydrate-block-Poly(3-hexylthiophene) Copolymer

Yoko Sakai-Otsuka, [START_REF] Segalman | Block Copolymers for Organic Optoelectronics[END_REF] Yoshiharu Nishiyama, [START_REF] Segalman | Block Copolymers for Organic Optoelectronics[END_REF] Jean-Luc Putaux, 1 Martin Brinkmann, [START_REF] Lee | Challenges and Opportunities in the Development of Conjugated Block Copolymers for Photovoltaics[END_REF] Toshifumi Satoh, [START_REF] Zhang | Over 14% Efficiency in Polymer Solar Cells Enabled by a Chlorinated Polymer Donor[END_REF] Wen-Chang Chen, [START_REF] Fu | Polymer Donors for High-Performance Non-Fullerene Organic Solar Cells[END_REF] and Redouane Borsali 1 * 1) Univ Grenoble Alpes, CERMAV, CNRS, F-38000 Grenoble, France

Synthesis of ethynyl-functionalized P3HT

The Br/H-terminated P3HT (1.1 g, 0.27 mmol, 1 equiv.), Pd2(dba)3 (15 mg, 0.016 mmol, 0.06 equiv.), and Pd(P(t-Bu3)2 (22 mg, 0.042 mmol, 0.16 equiv.) were added to a flask and dissolved in dry THF (160 mL) under argon. Ethynyltributylstannaane (2.6 g, 8.2×10 -3 mol, 31 equiv.) was added to the flask and the mixture was stirred at room temperature for 24 h under an argon atmosphere. The mixture was then precipitated into cold methanol to give mono-ethynylfunctionalized P3HT as a dark purple solid (yield: 62 %). [START_REF] Segalman | Block Copolymers for Organic Optoelectronics[END_REF] H NMR (400 MHz, CDCl3): δ (ppm): 7.05-6.85 (m, aromatic), 3.53 (s, -CºC-H), 2.84-2.50 (m, α-CH2), 1.71 (m, β-CH2), 1.48-1.34 (m, -CH2-CH2-CH2-CH3), 0.92 (br, -CH3). SEC: Mw = 6210 g mol -1 , Mn = 5670 g mol -1 , Đ = 1.07.

Synthesis of poly (3-hexylthiophene)-b-peracetylated maltoheptaose (P3HT-b-AcMal7)

In a two-neck round-bottom flask (flask 1), AcMal7-N3 (0.86 g, 0.4 mmol, 1.5 equiv.) and PMDETA (85 µL, 0.4 mmol, 1.5 equiv.) were dissolved in THF (10 mL), degassed by bubbling with argon for 5 min and stirred at room temperature. In a second two-neck round-bottom flask (flask 2), alkyne-P3HT (1.00 g, 0.3 mmol, 1 equiv.) and CuBr (0.06 g, 0.4 mmol, 1.5 equiv.) were dissolved in THF (90 mL), degassed by bubbling with argon for 5 min and stirred at room temperature. The content of flask 1 was transferred to flask 2 via cannula under argon atmosphere.

The reaction mixture was stirred at room temperature for 4h until the SEC traces showed complete disappearance of the peak of starting material. The solution was passed through a neutral alumina column to remove copper salt. After concentration, the product was recovered by precipitation in cold acetone and dried under reduced pressure to yield the P3HT-b-AcMal7 block copolymer as a purple solid (1.17 g, 75 %).