II.2 Synthesis of PE

IV.4.2 Some examples

II.2.3 Vin-PE-Vin features

II.3.2 Characterizations of Vin-PE-DMMS, Vin-PE-DMVS and Vin-PE-TMS

The Mn NMR value was determined using 1 H-NMR. The main methylene hydrogen atoms (I-(CH 2 )-), for the vinyl hydrogen atoms (ICH 2 =CH-), for the methylene group adjacent to the silicon group ((I-CH 2 -Si), and by using the equation Mn = 21[(I-(CH 2 )-+ I-CH 2 -Si )/ICH 2 =CH-] + 146 (for Vin-PE-DMMS), + 158 (for Vin-PE-DMVS), + 162 (for Vin-PE-TMS). c The Mn SEC value and dispersity were determined by HT-SEC in 1,2,4-trichlorobenzene at 150 °C using the RI signal and a calibration with PE standards. The integration was done on the whole distribution. d The functionalities were calculated using 1 H NMR using the following equation: F-CH 2 -Si = (I-CH 2 -Si /2) / ((I-CH 2 -Si /2) + (I-CH 3 /3)). e Degree of crystallinity (Xc) and melting temperatures (Tm) were determined using the second heating of DSC analysis. f Vinyl functionality per polymer chain was calculated using Mn SEC (comb/star-Vin-PE-X) / Mn SEC (Vin-PE-X). For X = DMMS and TMS, Mn SEC (comb/star-Vin-PE-X) corresponds to the distribution associated to the condensed chains with an elution volume range of [19-21.5] and [18-21] mL i.e. 11270 g mol -1 and 13875 g mol -1 respectively. In the case of X = DMVS, Mn SEC (comb-Vin-PE-DMVS) = 3740 g mol -1 Table 10 Table 10 Features of the α,ω-trimethoxysilyl polyethylenes synthesized via thiol-ene reaction on α,ω-vinyl polyethylenes as starting material

Polymers M Ɖ a α,ω-vinylpolyethylene (divinyl-PE) α,ω- trimethoxysilylpolyethylenes (PE-

II.2.2 Photo-oxidation

Covalent adaptable networks

k -1 k -1 k k k -1 k k k -1 log k 1/T log k /k -1 log k log K a = log (k -1 /k ) 1/T … … G 0 ≈ νkT G 0 ≈ νkT

Scheme

IV.3.3 Limitations of siloxane exchanges

P4-t Bu/H2O, TMAOH CsOH Scheme 48

Scheme 48 Overall mechanism of the siloxane bond exchange using CsOH, TMAOH and P4-t Bu. For P4-t Bu, the notation implies the activation with water. a Obtained using the method detailed in Chapter 2, Table 2. b Obtained from HT-SEC at 150 °C in TCB using PE standards.

II.3.3 Conclusion

IV.1.2 Mechanistic proposition of the condensation of methoxysilylgroup using phosphazene base

c Second heating of Differential Scanning Calorimetry (DSC) analysis using the standard melting enthalpy of PE: 293 J g -1

EBC-TMS

IV.2.2 Gel content

II.2 Formation of a gel covalently crosslinked in a highly dilute medium

The first step

IV.1.2 Influence of the ratio SiH/Vinyl

IV.1.3 Molar mass of polyethylene segments

PE-1000 PE-2400

Table 20 All the synthetic procedures are detailed in Table 3.

-0,3 -0,2 -0,1 0,0 0,1 0,2 0,3 0,4 0,00 0,02 0,04 0,06 0,08 0,10 0,12 0,14 -0,1 0,0 0,1 0,2 0,3 0,4 0,5 -0,02 0,00 0,02 0,04 0,06 0,08 0,10 0,12 0,14 -0,5 -0,4 -0,3 -0,2 -0,1 0,0 0,1 0,2 0,3 -0,005 0,000 a-f Characterization of divinyl-PE telechelic polymers. g-j Characterization of the aerogels after sublimation of CDD. a Determined by high-temperature SEC using PE calibration. b Determined by 1 H NMR. c Intrinsic viscosity in TCB at 150°C determined by high-temperature SEC using the differential viscometer. d Critical overlap polymer fraction estimated from the intrinsic viscosity using φ*=1/[η]. e Determined by DSC. f Crystallinity determined during the first heating by DSC from melting enthalpies using ΔHm = 293 J.g -1 as reference. g Crystallinity of aerogels determined as in f . h Apparent densities of aerogels. i Compression modulus of aerogels. j Melting temperature of aerogels as in e .

V.2 Shape-memory effect

PE-2000

Figure 1 Figure 2 Figure 3

 123 Figure 1 Représentation schématiques des différentes architectures de polyéthylènes obtenues au cours de ces travaux à partir de la condensation de groupements méthoxysilyle de PE hétéro-téléchéliques.

  polymerization of ethylene .......................................... II.2.2 Catalytic polymerization of ethylene ........................................ II.2.3 Conclusions .............................................................................. II.3 Conclusions ................................................................................coordinating functional groups ...................................... III.1.2 Low coordinating functional groups ......................................... Diene METathesis (ADMET) and Ring Opening Metathesis Polymerization (ROMP) ............................................................ III.2.2 Copolymerization of ethylene with conjugated dienes ............. -graft-trialkoxysilane ........................................... Coordinative chain transfer polymerization ................................... IV.2.1 The concept of catalyzed chain growth .................................... IV.2.2 The nature of the chain transfer agent ..................................... of polybutadiene.............................................. IV.3.2 Depolymerization via ADMET ................................................... IV.3.3 Ring opening polymerization followed by hydrogenation ........ IV.3.4 Chain doubling of monounsaturated fatty acids ....................... IV.3.5 Taking advantage of β-H elimination ........................................ IV.4 The case of alkoxysilyl-end chain functionalization ....................... IV.4.1 The interest .............................................................................. IV.4.2 Some examples ........................................................................

  Scheme 1

  Scheme 13

  Scheme 30

Figure

  Figure 6 1 H NMR spectra (363 K, TCE/C6D6 2/1 v/v) of a) Vin-PE-DMMS, b) Vin-PE-DMVS, c) Vin-PE-TMS

Figure 7

 7 Figure 7 Highlight of in situ condensation of Vin-PE-DMMS at 150 °C in TCB. The two samples have been respectively left for solubilization during 15 min and 5 hours before SEC analysis.

  Figure 26 m z n n

  Figure 8Table5

T

  Figure 8 1 H NMR (363 K, TCE/C6D6 2/1 v/v) spectra of copolymers of ethylene and butadiene with ethylene content of 92 mol% (EBC92), 97 mol% (EBC97), 98 mol% (EBC98) and 99 mol% (EBC99), obtained at 90 °C, 4 bars, [Nd] = 150 μmol -1 , [BOMAG] = 1 mmol L -1 , with {Me2Si(C13H8)2Nd-(BH4)2Li(THF)}2/MgR2 as a catalytic system

Figure 10 Figure

 10 Figure 10

aaEquationFigure 11 Figure 11 Figure 11

 111111 Scheme 33

Figurea

  Figure 12 1 H NMR (363 K, TCE/C6D6 2/1 v/v) spectra and HT-SEC chromatograms (from refractive index detector) of a) d) comb-Vin-PE-DMMS, b) e) comb-Vin-PE-DMVS, c) f) star-Vin-PE-TMS

FigureFigure 17 Figure 18

 1718 Figure 13 13 C NMR (363 K, TCE/C6D6 2/1 v/v) spectrum of a) comb-Vin-PE-DMMS and b) star-Vin-PE-TMS, arrows correspond to carbons adjacent to the silicon atom

Figure 19 Figure 19 Figure 20 Figure 20

 19192020 Figure 19

Figure 21 Figure 21

 2121 Figure 21

aFigure 22 Figure 22 aAFigure 29 Figure 30 T

 22222930 Figure22

Figure31aFigure 31 .ModulusFigure 32 IIIFigure 34

 313234 Figure31a

Figure 37

 37 Scheme 37 Main covalent exchange reactions that enable flow properties in CANs. Reproduced from ref.56

  Figure39

Figure 39 IV

 39 Figure 39 Reversible boronic ester bonds on polyolefin elastomers and Arrhenius plot of the relaxation times in function of the inverse of the temperature. Reproduced from ref. 106

Figure 40 Figure 40

 4040 Figure 40

Figure 41 Figure 41

 4141 Figure 41

Figure 42 Figure 42

 4242 Scheme 44

Figure 44

 44 Figure 43

Figure 45

 45 Figure 45c

Figure

  Figure 48 29 Si NMR spectra of TMA-TMS in THF-d8 at RT. Left: 29 Si NMR, right: 29 Si decoupled with 1 H.

Figure 54 Figure 58

 5458 Figure 50

Figure 60 Figure 60 Figure 61 Figure 62

 60606162 Figure 58

Figure 63 Figure 64

 6364 Figure63

Figure 65 Figure 66

 6566 Figure64

aP4Figure 68

 68 Figure 68 η

Figure

  Figure 69 Process of PE-TMS2 with various concentrations of P4-t Bu from 0 to 13600 ppm.

Figurea

  Figure 71 Gel content determined by gravimetric measurement of the dried gel that was immerged at 150 °C in xylene for 5 days.

Figure 72 Figure 72 Figure 73 Figure 74 Figure 75

 7272737475 Figure 72

  Figure 75b

Figure 76 a

 76 Figure 76 a) Time-profile of experiments run from 135 to 150 °C for monitoring cross-linking and deactivation of EBC-TMS in presence of P4-t Bu (3040 ppm). b) Corresponding cycles of stress relaxation experiments of 2 hours each at increasing temperatures (γ = 3%).

  Figure 77Table19

Figure 77 Figure 78

 7778 Figure 77 Determination of the gel content by gravimetric analysis by drying the gel that was immerged in xylene for 5 days at 150 °C.

Figure 80

 80 Figure 80 Polyethylene aerogel preparation (10 wt% of UHMWPE in decalin) followed by a sc-CO2 extraction. Scanning electron microscopy (SEM) images of the materials are given. Reproduced from ref 20 .

Figure 81 Figure 81

 8181 Figure

a

  Figure82

Figure 82

 82 Figure 82 Schematic representation of hydrosilylation reaction between an alkene and a hydrosilane leading to the hydrosilylation product (formation of Si-CH2 bond) and to side reactions' products.

Figure 85 Figure 86 Figure 87

 858687 Figure83

  Figure 88 Variation of the ratios SiH/Vinyle (1/1, 1.5/1, 2/1 and 3/1). Storage modulus obtained after 3 hours of reaction (a) second heating curves of DSC of the corresponding aerogels (b) and N2 physisorption experiments (d). Preparation: 6 wt% of PE-2000, reaction time = 3 hours at 110 °C, CL-1900, 300 ppm (NHC-i Pr)Pt(dvtms), recrystallized at 2 °C h -1 (slow crystallization from 110 °C to RT).

Figure 89

 89 Figure 89

Figure 90 Figure 90 Figure 91 Figure 91 Figure 97

 9090919197 Figure 90

Figure 100

 100 Figure 98sc

Figure 101 Figure 102 Figure 103

 101102103 Figure 101 Analysis of shape-memory performance in PE-2000 aerogel. i) 50% compression step at 125 °C, ii) cooling step at 3 °C min -1 while maintaining the compression, iii) release of stress, iv) heating at 3 °C min -1

Figure 3 VIIFigure 104

 3104 Figure3

Table of contents

 of

	Résumé…………………………………………………………………………..I
	Table of contents……………………………………………………….…VI
	Abbreviations…………………………………………………………………1
	General introduction………………………………………………………7
	Part I
	Synthesis of functional polyethylenes

Table 1 Table 1 Three classes of PE: LDPE, LLDPE and HDPE LOW DENSITY POLYETHYLENE (LDPE) LINEAR LOW-DENSITY POLYETHYLENE (LLDPE) HIGH DENSITY POLYETHYLENE (HDPE)

 11

III.1.2 Low coordinating functional groups p III.1.2.6 Borane side groups III.1.2.7 Para-tolyl side groups

	III.1.2.9 Unsaturated side groups
	P
	p
	p
	p
	III.1.2.8 Halogenated groups

p III.

2 Functional polyethylene from diene and cyclic olefin III.2.1 Acylic Diene METathesis (ADMET) and Ring Opening Metathesis Polymerization (ROMP) Scheme 11 General ADMET approach to obtain polyethylene

	et al.
	Scheme 11
	et al.	co

Scheme 12 Scheme 12 Example of polyethylene from ROMP followed by hydrogenation 74 III.2.2 Copolymerization of ethylene with conjugated dienes

Scheme 29 Scheme 29 Mono-methoxysilyl terminated polyethylenes 127-128 V Conclusion and positioning of this work VI References

	Processes Introduction to Industrial Polyethylene: Properties, Catalysts, and Processes
			Ind. Eng. Chem. Res.
	53
	Polymer (Guildf). 2
		ChemBioEng Rev. 4 Handbook of polymer synthesis
	Macromol. Chem. Phys. 214	Macromol. Chem. Phys. 204
	Polymer Materials, Macroscopic Properties and Molecular
	Interpretations	J. Catal. 3
			Chem. Rev. ACS Catal. 8
	116
	History of polyolefins	Adv.
	Catal. 33
		Ind. Eng. Chem. Res. 54
		Top. Catal. 7
			42
	Macromolecules 52
	Polyolefins: 50 years after Ziegler and Natta II Adv Polym Sci 258
	Macromolecules 44
			J. Polym. Sci. Part A
	The UHMWPE Handbook: Ultra High Molecular Weight Polyethylene in Total Polym. Chem. 37
	Joint Teplacement
		Angew. Chemie 19	Mater. Sci. Appl. 02

I Introduction .............................................................................. 79 II Synthesis of vinyl-functionalized PE by CCTP .............................. 81 II.1 A brief reminder of CCTP ...............................................................

81 II.2 Chain-end functionalization: Synthesis of homotelechelic divinyl-PE..82 II

  .2.1 The strategy ............................................................................. 82 II.2.2 The microstructure analysis ..................................................... 83 II.2.3 Vin-PE-Vin features .................................................................. 84

II.2.4 Conclusions .............................................................................. 84 II.3 Chain-end

Table 2 Features of Vin-PE-Vin, obtained after elimination of Vin-PE-I using t BuOK at 110°C II.2.4 Conclusions

 2

	M	Đ a
	a Determined by high temperature SEC (HT-SEC) using PE calibration. b Determined by 1 H NMR spectroscopy. c Melting
	temperatures and degree of crystallinity determined during the second heating of Differential Scanning Calorimetry (DSC)
	analysis using the standard melting enthalpy of PE: 293 J g -1
		β H

II.3 Chain-end functionalization: Synthesis of hetero- telechelic α,ω-vinyl-methoxysilyl polyethylenes (Vin-PE- Si(OR) x ) II.3.1 The strategy Scheme 32 Scheme 32 General pathways to obtain α-vinyl,ω-alkoxysilyl-polyethylene

Table 3 Characterizations of Vin-PE-DMMS, Vin-PE-DMVS and Vin-PE-TMS

 3

	M	M	M	Ɖ

Table 4 Table 4 Determination of the number of PE chain per silicon atom , Figure 23, Figure 24 and Figure 25 A B Vin-PE-DMMS 1.05 1.95 Vin-PE-DMVS 1.10 1.90 Vin-PE-TMS 1.03 2.97

 4

	a Theoretical molar mass: Mn Theo = (mPE obtained / Vtoluene) / (2*[Mg]0). b The Mn NMR value was determined using 1 H-NMR. The main
	methylene hydrogen atoms (I-(CH 2 )-), for the vinyl hydrogen atoms (ICH 2 =CH-), for the methylene group adjacent to the silicon group
	((I-CH 2 -Si), and by using the equation Mn = 21[(I-(CH 2 )-+ I-CH 2 -Si )/ICH 2 =CH-] + 146 (for Vin-PE-DMMS), + 158 (for Vin-PE-DMVS), + 162
	(for Vin-PE-TMS). c Second heating of Differential Scanning Calorimetry (DSC) analysis using the standard melting enthalpy of
	PE: 293 J g -1

Table 5 Microstructure analysis of the copolymers of ethylene and butadiene obtained at 90 °C, 4 bars, [Nd] = 150 μmol -1 , [BOMAG] = 1 mmol L -1 , with {Me2Si(C13H8)2Nd- (BH4)2Li(THF)}2/MgR2 as a catalytic system Microstructure EBC99 EBC98 EBC97 EBC92 % ethylene 99.18 98.39 97.06 92.29 % vinyl unit % cyclohexyl unit % trans unit V = Ic

Table 6 . Equation 2 Equation 2 Broadhurst relation Table 6 Determination of melting temperatures (Tm) of copolymers of ethylene and butadiene: a comparison of experimental Tm and Broadhurst relation EBC92 EBC97 EBC98 EBC99 n a Estimated Tm b (°C) Tm c (°C) XC (%)

 6

	Second heating of Differential Scanning Calorimetry (DSC) analysis

a Number of carbon atoms of ethylene units. b Application of Equation 2. c

.3 (C5Me5)2NdCl2Li(OEt2)2/BOMAG catalytic system II.4.3.5 The strategy β β II.4.3.6 The microstructure analysis and thermal analysis

Table 5 Table 7 β

 57

Scheme 35 Scheme 35 Simplified thermo-oxidation (orange, small frame) and photo-oxidation (blue, large frame) mechanisms of PE 28 II.2.3 Thermochemistry

	Scheme 35
	et al.

via II.

2 Thermo-mechanical property

Table 12 Table 12 Summary of the dynamic polymer network reviewed in the literature that involve Si- O-Si exchangeable bonds.

 1212

Table 16 Table 16 Summary of the characteristic of PE-TMS2 studied in this section Mn (Đ) a

 1616

Table 17 Gel content measurement of PE-TMS2 vitrimer in presence of 3040 ppm of P4-t Bu that was crosslinked for 6 hours at 140 °C

 17

	Table 17
	et al.
	et al.

Table 18 Summary of the characteristic of the copolymers of ethylene-butadiene studied in this section Ethylene content (%) a Mn (Đ) b (g mol -1 ) Tm (°C) c XC (%) c Ntrimethoxysilyl functions / chain 97.7 IV.2.1 Crosslinking monitoring and stress relaxation via rheology EBC-TMS P4-t Bu P4-t Bu EBC-TMS Figure 76

 18

Table 19 Gel content measurement of EBC-TMS vitrimer in presence of 3040 ppm of P4-t Bu that was crosslinked for 6 hours at 140 °C

 19

	EBC-TMS	15.6	0	0
	EBC-TMS + 3040 ppm P4-t Bu	35.1	30.3	86

P4-t Bu P4-t Bu HP4-t Bu] + [HO] -, HP4-t Bu] + [ RSi (CH3)2O] -(with R = CH3 or CH=CH2). via TMAOH P4-t Bu P4-t Bu TMA2-PDMS Cs-TMS P4-t Bu via P4-t Bu P4- t Bu P4-t Bu Scheme 52 Scheme 52 Formation of highly aggregated Si-O-R regions during the crosslinking reaction via condensation of trimethoxysilyl-functionalized polyethylenes. P4-t Bu. P4-t Bu

	VI Experimental section
	VI.1 Materials
	PE segments
	Si-O-Si crosslinks
	t
	M
	M
	VI.2

Synthesis part VI.2.1 Molecular study VI.2.2 Synthesis of Cesium, tetramethyl ammonium and tetrabutyl ammonium trimethylsilanolate VI.2.3 Synthesis of silicone rubber via hydrosilylation VI.2.4 Introduction procedure of siloxane bond exchange additive in the silicone rubber VI.2.5 Preparation of polyolefin vitrimers

	I Introduction
	VI.3.5 TGA
	VI.3 Instrumentations
	VI.3.1 NMR
		sc
	VI.3.2 GC	Figure 80
	VI.3.3 Rheology
	VI.3.4 DSC
		t
	t

Table 20 Table 20 Characterization of divinyl-PE telechelic polymers

 2020

Table 21 Table 21 Characterization of polymethylhydrosiloxane (PMHS) used as crosslinker Crosslinker Mn a (g mol -1 ) [Si-H] b (mol g -1 ) CL-390 CL-1900 II.3 The gel crystallization

 2121 From commercial specifications. b Determined by 1 H NMR spectroscopy using dimethylcarbonate as internal reference.

a

Table 22 Summary of the aerogels features obtained from PE-600, PE-1000, PE-1500, PE-2000 (6 wt% in Cyclo-C12) using CL-390 as crosslinker (SiH/Vinyl = 2/1) and 300 ppm (NHC- iPr)Pt(dvtms).

 22

					Polymers					Aerogels
	Sample	Mn a (g mol -1 )	Đ a	divinyl-PE (%) b	[η] c (dL g -1 )	φ* d (wt%)	Tm e (°C)	Xc f (%)	Xc g (%)	d h (mg cm -3 )	E i (kPa)	Tm j (°C)
	PE-600	620	1.2	95	0.019	53	71	69	37	74	93	60
	PE-1000	1050	1.2	94	0.030	33	105	77	36	51	130	92
	PE-1500	1450	1.2	93	0.038	27	114	81	43	83	150	102
	PE-2000	1920	1.2	93	0.047	21	121	83	42	120	600	111
	UHMWPE	3-6.10 6	-	-	-	-	132	39	73	110	18	134

Table 1

 1

Si NMR spectrum of Cs-TMS

Angew. Chemie Int. Ed. English 24 J. Am. Chem. Soc. 106 J. Mol. Catal. A Chem. 128 Comptes Rendus Chim. 9 Adv. Synth. Catal. 344 et al. J. Am. Chem. Soc. 123 J. Am. Chem. Soc. 123 et al. Organometallics 17 et al. Science 287 Macromolecules 34 et al. J. Am. Chem. Soc. 121 Angew. Chem. Int. Ed. 41 Angew. Chem. Int. Ed. 53 Macromolecules 38 Macromolecules 39 et al. Angew. Chem. Int. Ed. 58 J. Polym. Sci. Polym. Chem. Ed. 15 Am. Chem. Soc. Polym. Prepr. Div. Polym. Chem. 17 et al. Macromolecules 46 Angew. Chem. Int. Ed. 59 ACS Catal. 9 Polymer (Guildf). 38 Macromolecules 48 Macromolecules 50 J. Am. Chem. Soc. 120 J. Am. Chem. Soc. 118 Organometallics 26 Chem. Commun. 2 J. Am. Chem. Soc. 132 Angew. Chem. Int. Ed. 47 J. Am. Chem. Soc. 131 J. Am. Chem. Soc. 129 J. Am. Chem. Soc. 129 J. Am. Chem. Soc. 131 J. Am. Chem. Soc. 134 Macromolecules 43 J. Am. Chem. Soc. 129 et al. J. Am. Chem. Soc. 133 ACS Macro Lett. 1 J. Chem. Soc. Cem. Commun. 891, et al. J. Am. Chem. Soc. 107 J. Am. Chem. Soc. 107 et al. Sci. Adv. 3 Polym. Int. 37 J. Polym. Sci. Part A Polym. Chem. 35 J. Polym. Sci. Part A Polym. Chem. 36 et al. Macromolecules 47 Functionalization of Polyolefins The Compounding and Vulcanization of Rubber Rubber Technology Chem. Rev. 109 Chem. Soc. Rev. 42 Coord. Chem. Rev. 250 Handbook of Transition Metal Polymerization Catalysts Synthetic Methods in Step-Growth Polymers Macromol. Chem. Phys. 215 Colloid Polym. Sci. 282 Macromolecules 40 Chem. Soc. Rev. 40 Monatshefte fur Chemie 146 Polymer (Guildf). 51 et al. ACS Catal. 6 et al. Chem. Rec. 4 J. Am. Chem. Soc. 125 Doktorsavhandlingar vid Chalmers Tek. Hogsk. Acc. Chem. Res. 51 J. Am. Chem. Soc. 139 Polym. Int. 65 Angew. Chem. Int. Ed. 53 et al. Macromolecules 36 Macromolecules 36 Chem. Commun. 49 Macromol. Rapid Commun. 28 Dalt. Trans. 39 J. Am. Chem. Soc. 126 Macromolecules 38 et al. J. Am. Chem. Soc. 135 et al. Macromolecules 50 Angew. Chemie Int. Ed. 35 Chem. Rev. 113 et al. ACS Catal. 6 Macromolecules 42 et al. ACS Catal. 9 Polym. Chem. 1 Chem. -A Eur. J. 13 Polym. Chem. 1 Angew. Chem. Int. Ed. 52 Macromolecules 50 Angew. Chem. Int. Ed. 54 Die Makromol. Chemie, Rapid Commun. 12 Die Makromol. Chemie, Rapid Commun. 14 et al. J. Polym. Sci. Part A Polym. Chem. 37 Macromolecules 28 Macromolecules 49 Angew. Chem. Int. Ed. 56 Metal Catalysts in Olefin Polymerization Metal Catalysts in Olefin Polymerization 49 Polym. Chem. 9 Polym. Chem. 5 et al. Polym. Chem. 5 et al. Macromol. Chem. Phys. 218 et al. Macromolecules 48 et al. Polym. Chem. 7 et al. Polym. Chem. 8 CHAPTER 2 Synthesis of vinyl-and methoxysilylfunctionalized polyethylenes

Angew. Chemie -Int. Ed. 52 Macromol. Chem. Phys. 205 Macromolecules 42 J. Chem. Phys. 36 et al. ACS Catal. 6 Macromolecules 33 et al. ACS Catal. 6 Dokl. Chem. 424 Polym. Chem. 5 Angew. Chemie -Int. Ed. 54 Angew. Chemie -Int. Ed. 54 V Conclusions VI References Handbook of polyethylene Marcel Dekker Inc. Science. 334 Colloid Polym. Sci. 289 et al. Polymer (Guildf). 58 Adv. Mater. 4 Commercial polymer blends Polymer Blends Handbook Polymer (Guildf). 161 Multimodal Polymers with Supported Catalysts et al. Front. Ecol. Environ. 13 Nat. Rev. Microbiol. 18 Polym. Degrad. Stab. 18 Int. Biodeterior. Biodegrad. 88 J. Polym. Sci. 20 Chem. Rev. 57 Energy Transfer in Polymers The Radiation Chemistry of Macromolecules Nature 4343 Nucl. Instruments Methods Phys. Res. Sect. B Beam Interact. with Mater. Atoms 236 Nucl. Instruments Methods Phys. Res. Sect. B Beam Interact. with Mater. Atoms 185 J. Am. Chem. Soc. 76 J. Polym. Sci. 14 Chem. Rev. 56 Int. J. Appl. Radiat. Isot. 3 Nature Polym. Degrad. Stab. 53 Eur. Polym. J. 25 J. Photochem. Photobiol. A Chem. 296 Photochem. Photobiol. Sci. 8 Eur. Polym. J. 28 Polym. J. 27 J. Appl. Polym. Sci. 2 J. Appl. Polym. Sci. 9 Polymer Materials, Macroscopic Properties and Molecular Interpretations The physics of rubber elasticity J. Biomed. Mater. Res. -Part A 66 J. Biomed. Mater. Res. -Part B Appl. Biomater. 70 Functionalization of Polyolefins J. Appl. Polym. Sci. 81 J. Polym. Sci. Part A Polym. Chem. 36 Polymer (Guildf). 111 J. Appl. Polym. Sci. 108 Doktorsavhandlingar vid Chalmers Tek. Hogsk. Acc. Chem. Res. 51 J. Am. Chem. Soc. 139 Mater. Res. 20 Adv. Polym. Technol. 9 Sicot-J 6 J. Orthop. Res. 17 et al. Ind. Eng. Chem. Res. 58 Nat. Rev. Chem. 1 Polym. Rev. 60 et al. Polym. Chem. 10 ACS Cent. Sci. 6 J. Am. Chem. Soc. 141 Macromolecules 50 Adv. Funct. Mater. 27 J. Am. Chem. Soc. 137 et al. Science (80-. ). 295 Macromolecules 43 Angew. Chemie -Int. Ed. 51 Nat. Mater. 10 J. Appl. Polym. Sci. 134 et al. ACS Macro Lett. 6 Angew. Chemie -Int. Ed. 55 J. Am. Chem. Soc. 137 ACS Appl. Mater. Interfaces 11 J. Am. Chem. Soc. 140 et al. Adv. Funct. Mater. 25 et al. Nat. Commun. 8 et al. J. Polym. Sci. Part A Polym. Chem. 55 et al. J. Polym. Sci. Part A Polym. Chem. 56 et al. Macromolecules 51 ACS Macro Lett. 6 et al. Green Chem. 20 J. Am. Chem. Soc. 139 J. Am. Chem. Soc. 141 et al. J. Mater. Chem. A 6 et al. J. Mater. Chem. A 7 J. Am. Chem. Soc. 141 ACS Macro Lett. 7 Macromol. Rapid Commun. 40 Chem. Sci. 11 Prog. Polym. Sci. 104 Angew. Chemie -Int. Ed. 58 J. Am. Chem. Soc. 137 et al. Macromolecules 49 et al. Angew. Chemie -Int. Ed. 58 et al. Science. 356 J. Am. Chem. Soc. 141 Macromolecules 51 et al. Science. 65 Macromolecules 52 J. Am. Chem. Soc. 134 Polym. Chem. 10 J. Mater. Chem. A Polym. Chem. 10 Polymer (Guildf). 199 Macromolecules 53 Macromolecules 51 et al. Polym. Chem. 11 J. Am. Chem. Soc. 76 J. Am. Chem. Soc. 76 Macromolecules 48 De la macromolécule au matériau polymère et al. Adv. Mater. 31 ACS Macro Lett. 9 et al. Green Chem. 20 et al. Angew. Chemie -Int. Ed. 59 et al. Chem. Eng. J. 405 J. Am. Chem. Soc. 76 J. Am. Chem. Soc. 134 Macromolecules 48 De la macromolécule au matériau polymère J. Am. Chem. Soc. 77 Polymer (Guildf). 13 Compr. Organomet. Chem. 2 Compr. Polym. Sci. Suppl. J. Inorg. Organomet. Polym. 1 J. Am. Chem. Soc. 76 Macromolecules 48 ACS Macro Lett. 9 Sci. Rep. 10 et al. Adv. Mater. 31 Polym. Chem. 10 J. Inorg. Organomet. Polym. 9 J. Inorg. Organomet. Polym. Mater. 14 Chem. Sci. 9 Polymer (Guildf). 49 Macromolecules 36 Macromol. Rapid Commun. 16 Prog. Polym. Sci. 36 Org. Chem. Front. J. Org. Chem. 79 Angew. Chemie -Int. Ed. 59 J. Am. Chem. Soc. 66 et al. J. Am. Chem. Soc. 125 J. Am. Chem. Soc. 80 Anal. Sci. 25 Anal. Chem. 75 Macromolecules 51 Phys. Rev. B -Condens. Matter Mater. Phys. 74 et al. Dow Corning Dow Corning Polym. Chem. 11 et al. Science. 356 J. Mater. Chem. A Prog. Polym. Sci. 39 et al. J. Organomet. Chem. 692 J. Organomet. Chem. 686 CHAPTER 5 Polyethylene aerogels I

VI.1 Materials

Abstract

The aim of this work is to develop materials based on polyethylene chemically cross-linked by siloxane bonds in order to meet various applications. The first one aims at developing PE vitrimers that are able to relax via siloxane bond exchanges. The second application relates to the improvement of the mechanical properties of aerogels based on polyethylenes. In both cases, a preliminary study has first allowed to introduce reactive functions to polyethylene while maintaining its intrinsic property of semi-crystalline polymer. For this purpose, the use of coordinative chain transfer polymerization was used in this work in order to obtain polymers of controlled molar masses with high functionalization rates. Thus, telechelic polyethylenes (bearing vinyl and/or trimethoxysilyl functions) and semi-crystalline copolymers of ethylene with butadiene, bearing lateral vinyl functions, have been synthesized. By combining this type of polymerization, in which C2P2 has acquired expertise over the past 20 years, with organic chemical reactions such as thiol-ene or hydrolysis-condensation, functional polyethylenes with different architectures (linear, brush, star) could be obtained. These polymers have been valorised by their use in the fields of dynamic and porous materials. The strategy chosen for the first one aims at inducing dynamic covalent exchanges within cross-linked materials. For this purpose, the dynamic exchange reactions of siloxanes were studied in three different systems: small model molecules based on disiloxanes, a network cross-linked by hydrosilylation based on polydimethylsiloxane and a network based on polyethylenes. The latter was obtained by condensation of trimethoxysilyl-functions by basic route and the thermal, rheological (crosslinking, stress-relaxations…) properties of these materials were analyzed. In addition, polyethylenes functionalized at the both chain-ends by vinyl functions were involved in hydrosilylation reactions in a very dilute medium in the presence of a platinum-based complex in order to create a covalent network. The original use of a solvent crystallizable at room temperature and easily sublimable, allowed the porous structure of the aerogel to be controlled and a structure-property relationship (thermal and mechanical) was established.

Title

Deciphering the use of dynamic siloxane exchanges to obtain polyethylene vitrimer networks

Keywords

Semi-crystalline polymers, functionalization, rheology, catalysis, covalent dynamic networks, (aero)gels, materials, polydimethylsiloxane

Résumé

Ce travail vise à développer des matériaux à base de polyoléfines réticulées chimiquement par des liaisons siloxanes afin de répondre à deux applications. La première vise à développer des polyéthylènes (PE) vitrimères. La

Titre

Utilisation d'échanges dynamiques de siloxanes dans des réseaux vitrimères à base de polyéthylène

Mots-clés

Polymères semi-cristallins, fonctionnalisation, rhéologie, catalyse, réseaux dynamiques covalents, (aéro)gels, matériaux, polydiméthylsiloxane


Unmanned Aerial Vehicles (UAVs)

Autonomous flying devices providing services to targets on the ground Air-to-ground and air-to-air communications Light materials with low energy consumption machines

Signaux et images numéri robotique

Traitement du signal (audio, image, v pour des applications dans les doma la robotique, des télécommunication multimédia, du médical et des géosc

Interesting techniques

Using Bloom fitler for complete information Pivotal (or Cube) Sampling for sliding windows

π = 0.3 π = 0.2 π = 0.5 π = 0 π = 0.3 π = 0 π = 0.8 π = 0.4 π = 0.2 π = 1 π = 1 π = 1 π = 1 π = 1 π = 1 π =
π = 1 π = 1 π = 1 π = 1 π = 1 π = 1 π = 1

Guaranteed properties

Stable number of sample among a window Difficult to predict the selection in advance Fine stratification : balanced spreading according to time

Possible to generalize the pivotal sampling

Contest of r items instead of 2 at each round : increase the unpredictability

TUTORIAL'S NEXT STEPS

Given a set of targets located on the ground field, the goal is to monitor the area with flying drones to cover as many targets as possible and ensure the connectivity with a base station to continuously report or broadcast information to and from the sink

Vehicle Spreading using Self-organized Parallel Algorithm

Extend existing works in the following way :

Unknown target locations

The drones must fly over the field and detect the targets while flying over.

Distributed decentralized algorithm

Run by each drone using only information from their neighbors.

Connectivity guarantee between the discovered targets and the sink

Drones form a multi-hop aerial wireless path Once a target is detected, the drones self-organize to construct the path.

Expansion iteration to use any available drones

S ⌧ 0 ⌧ 1 ⌧ 2 ⌧ 3 ⌧ 4 ⌧ 5 ⌧ 6 ⌧ 7 ⌧ 8 ⌧ 9 . . 29/09/2016 DRONE FLEET COORDINATION | ECOLE D'ÉTÉ RESCOM | YANN BUSNEL | 28/06/22 S ⌧ 0 ⌧ 1 ⌧ 2 ⌧ 3 ⌧ 4 ⌧ 5 ⌧ 6 ⌧ 7 ⌧ 8 ⌧ 9 . .

NOTHING BEATS A GOOD EXAMPLE! 45

Round 1 -End of Expansion phase

All drones have spread around S

Connectivity is guaranteed

S ⌧ 0 ⌧ 1 ⌧ 2 ⌧ 3 ⌧ 4 ⌧ 5 ⌧ 6 ⌧ 7 ⌧ 8 ⌧ 9 . .

Key

Irremovable

Connectivity is still guaranteed

From any drone using the previous spanning tree Use of the right hand algorithm to find a path to the sink

S ⌧ 0 ⌧ 1 ⌧ 2 ⌧ 3 ⌧ 4 ⌧ 5 ⌧ 6 ⌧ 7 ⌧ 8 ⌧ 9 . .

Key

Irremovable

Connectivity is still guaranteed

By transitivity from the previous state Optimal cannot be depicted

S ⌧ 0 ⌧ 1 ⌧ 2 ⌧ 3 ⌧ 4 ⌧ 5 ⌧ 6 ⌧ 7 ⌧ 8 ⌧ 9 . .

Key

  'information. Il const un pôle de recherche d'excellence ave informatique, la sécurité des système nouvelles architectures logicielles, la virtuelle, l'analyse des masses de don Implanté à Rennes, Vannes, et Lannio est au coeur d'un écosystème régiona riche en recherche et innovation. Le laboratoire se positionne comme la référence en France avec une expertise reconnue à l'international au travers de nombreux contrats européens internationales. Tourné vers le futur l'IRISA se veut au coeur de la transition numérique e l'innovation au service de la cyberséc santé, l'environnement, les transports et la culture. L'IRISA est issu d'une volonté de colla entre huit établissements tutelles, me commun une force de femmes et d'ho qui donnent le meilleur d'eux-mêmes français dans le domaine de l'informatique et des nouvelles technologies de l'information. Il constitue un pôle de recherche d'excellence avec des informatique, la sécurité des systèmes, les nouvelles architectures logicielles, la réalité virtuelle, l'analyse des masses de données, Implanté à Rennes, Vannes, et Lannion, l'IRISA est au coeur d'un écosystème régional riche en recherche et innovation. Le laboratoire se positionne comme la référence en France avec une expertise reconnue à l'international au travers de nombreux contrats européens internationales. Tourné vers le futur l'IRISA se veut au coeur de la transition numérique et de l'innovation au service de la cybersécurité, la santé, l'environnement, les transports, l'énergie et la culture. L'IRISA est issu d'une volonté de collaboration entre huit établissements tutelles, mettant en commun une force de femmes et d'hommes qui donnent le meilleur d'eux-mêmes pour la recherche fondamentale et appliquée, la formation, les échanges interdisciplinaires, les transferts de savoir-faire et de technologie. ensemble des thématiques de l'informatique, allant de l'architecture des ordinateurs et des réseaux à l'intelligence en passant par le génie logiciel, les systèmes distribués et la réalité virtuelle. distribués au sens large, couvrant à la fois les systèmes d'exploitation distribués, les environnements d'exécution parallèle, les middleware et les frameworks permettant la conception et l'exécution d'applications distribuées. Architecture Développement d'architectures et d'outils de compilation pour les systèmes multi et many core hétérogènes, pour des plateformes d'usage général ou pour des systèmes embarqués, en prenant en compte les contraintes de performances, de temps-réel, de consommation ou de ressources limitées.

  ensemble des thématiques de l'informatique, allant de l'architecture des ordinateurs et des réseaux à l'intelligence en passant par le génie logiciel, les systèmes distribués et la réalité virtuelle.

•

  Probabilistic protocols (e.g. epidemic) based on periodic exchanges of information between participants Algorithms for wired networks based on high communication paradigms Large-scale systems design Overlay networks usually for one specific application Group nodes depending on computational power Algorithms based on centralized information gathering Centralized solutions not applicable • Low latency and battery consumption 1. Real time applications • Centralized information gathering and manual allocation of resources do not scale • Track the distribution of available resources 2. Large scale deployment • Important amount of data to process quickly and accurately • Diversity and dynamic nature of content 3Equivalent to anomaly detection Existing algorithms based on complete knowledge or high computational cost New approaches for real-time processing of massive (distributed) data flows Data streaming methods Sketch and sampling End-point computing optimization Analyze the data stream and retain only relevant information to reduce memory Process all the data in the stream on the fly, and to keep only summaries Extracts statistics on processed data streams, with bounded error probabilities Based on summaries that involve a significant loss of information, with sometimes drastic overestimation Interesting techniques Using Count-Min Sketch for complete information Histogram aggregates for sliding windows COMPUTE ⌈log 1/𝛿⌉ ESTIMATORS IN PARALLEL AND RETURN THE MINIMUM VALUE [CM05] G. Cormode and S. Muthukrishnan, An improved data stream summary: the count-min sketch and its applicaAons, in Journal of Algorithms, vol. 55, no. 1, pp. 58-75, 2005. G. Cormode and S. Muthukrishnan, An improved data stream summary: the count-min sketch and its applicaAons, in Journal of Algorithms, vol. 55, no. 1, pp. 58-75, 2005.Limit the amount of data stored in memory Computing exactly functions on these samples Depends strongly on the volume of data sampled, and their position on the stream

  Fig. 1: Triangular tessellation model.

  have moved to the border Autonomous movement away from the sink Well-balanced all around the borderConnectivity is guaranteedFrom any point of the border and thus from any drone in the fleet is self-defined by surrounding observation

  Use of the right hand algorithm when progression is not possible (due to a hole on the coverage -cf. t 6 )

  : 870 scenarios with < 10 tasks and 5 ≤ sensors ≤ 15 Total recharge time for all 2800 scenarios.

OBJECTIVES 33 Surpass, either in latency or battery consumption, two main approaches

29/09/2016 DRONE FLEET COORDINATION | ECOLE D'ÉTÉ RESCOM | YANN BUSNEL | 28/06/22 SOLUTION strictly local computation delegation of data to the cloud services on the Internet Innovative real-time solutions with low complexity in terms of memory, processing time, communication, etc.

Design a large-scale overlay network build and maintain application-level network link together participating processes communicate and inter-operate 29/09/2016 DRONE FLEET COORDINATION | ECOLE D'ÉTÉ RESCOM | YANN BUSNEL | 28/06/22 OPEN

QUESTIONS 34 Multi-topic openness involving cooperation between specialists from different fields Hot topic with various practical applications

	Security,
	Disaster management
	Energy
	Agriculture
	Traffic management
	etc.

During the Spanning phase Any drone that is not irremovable, nor on the new external border became Free Connectivity is still guaranteed

	NOTHING BEATS A GOOD EXAMPLE! NOTHING BEATS A GOOD EXAMPLE!		50 51
						.
	⌧ 1	⌧ 7	S	⌧ 5	⌧ 3 ⌧ 6	⌧ 9		Round 2 -By transitivity from the previous state Round 2 -
	⌧ 2
	⌧ 8		⌧ 0
	⌧ 4							Key
								Irremovable Irremovable
	.							Border Border
								Free Free
						DRONE FLEET COORDINATION DRONE FLEET COORDINATION	| |	ECOLE D'ÉTÉ RESCOM ECOLE D'ÉTÉ RESCOM	| |	YANN BUSNEL YANN BUSNEL	| |	28/06/22 28/06/22
	29/09/2016 29/09/2016

End of Spanning phase Border and Free drones extended the spanning tree to the external border Connectivity is still guaranteed

	NOTHING BEATS A GOOD EXAMPLE!				52
				.
		⌧ 5
			⌧ 6
	⌧ 1	⌧ 7
		S	⌧ 3	⌧ 9
						By transitivity from the previous round
	⌧ 2
	⌧ 8	⌧ 0
	⌧ 4					Key
						Irremovable
	.					Border
						Free
				DRONE FLEET COORDINATION	|	ECOLE D'ÉTÉ RESCOM	|	YANN BUSNEL	|	28/06/22
	29/09/2016

Require the implementation of sensor systems over long periods of time

Optimising the lifetime of each sensor is a key element Realistic assumption

Regular recharging is paramount

Energy harvesting model for both transmitters and receivers

Obtained from a RF-power harvesting module manufacturer Output: a set of UAV conflict-free trajectories fulfilling the positions computed by the MILP, while minimizing the overall duration for recharging the whole system.

ENERGY HARVESTING MODEL

Amount of power harvested by a sensor :

Received power at distance d :

-log-normal distribution with a shadowing coefficient σ -P 0 is the received power at reference distance Harvested energy of a sensor s for a given time period t :

Objective: Determine the optimal number of drones needed to recharge the sensors in the minimum amount of time.

OPTIMAL POSITIONING : MILP APPROACH

Objective: Determine the optimal number of drones needed to recharge the sensors in the minimum amount of time.

Define 2 continuous variables modeling the worst time λ 1 -the worst number of positions λ 2

We can combine the bi-objective into only one function

where a is an input parameter to balance the impact of the two objective functions

Take into account the following constraints

Number of used drones do not exceed the budget B Harvested energy of each sensor s must be fulfilled Total length of UAVs flying time cannot exceed the imposed time limit Not any drone can be placed above or under another one simultaneously Limit physical collisions between the drones as well as interference

Limit the total time spent on the set of charging positions P s of sensor s to the longest flying time of a drone [35,9,18,34,26,17,12,19] 1 = [5, 13, 23. 1, 25, 28, 39, 22, 37, 27. 29, 321 2 = [13, 23, 3, 25, 28, 8, 19, 36, 14] 3 = [35, 0, 18, 34, 26, 17, 15, 12] 4 = [10, 0, 38, 15, 4] 5 = [35, 9, 18, 21, 26, 17, 2] 6 = [5, 11, 13, 23, 1, 3, 25, 28, 27. 8, 19, 36, 32, 14] 7 = [10, 0, 38, 34, 15, 12] 8 = [35, 9, 18, 21, 26, 17, 2] 9 = [11, 31, 16, 30, 7, 6, 33, 24, 14] 10 = [5, 13, 23, 1, 25, 28, 39, 22, 27, 29, 36, 32] 11 = [20, 16, 30] Tasks by drone d [35,9,18,34,26,17,12,19] 1 = [5, 13, 23. 1, 25, 28, 39, 22, 37, 27. 29, 321 2 = [13, 23, 3, 25, 28, 8, 19, 36, 14] 3 = [35, 0, 18, 34, 26, 17, 15, 12] 4 = [10, 0, 38, 15, 4] 5 = [35, 9, 18, 21, 26, 17, 2] 6 = [5, 11, 13, 23, 1, 3, 25, 28, 27. 8, 19, 36, 32, 14] 7 = [10, 0, 38, 34, 15, 12] 8 = [35, 9, 18, 21, 26, 17, 2] 9

= [11,31,16,30,7,6,33,24, 14] 10 = [5, 13, 23, 1, 25, 28, 39, 22, 27, 29, 36, 32] 11 = [20, 16, 30] Tasks by drone


Thomas Houet

Chapter 7 -Geoprospective: looking for potential scenarios

Introduction

The future is by definition uncertain. While this can frighten, make one sceptical or guessing, another attitude can be anticipation which will result in defining various adaptation strategies. For example, when buying a property, everyone has information about the risks (floods, landslides, technological risks) linked to the property's location. The absence of anticipation consists of not considering a risk of flooding for example. A first strategy would be to accept the risk and adjust the way of living (upstairs only) or the architecture of the property (on stilts). The second strategy would be to refuse this location and look for another property outside a flood zone defined in a Flood Risk Prevention Plan (PPRI1 ). The last strategy could be to go beyond the geographical perimeter of the current regulation (look for an even more remote area, another locality or region) on the assumption that the current regulation defining PPRI is insufficient with regard to climate change.

While this example illustrates an individual choice, societal demand has evolved and the democratization of the concept of sustainable development since the 1970s (Meadows 1972) has made it possible to integrate this anticipation into current land-use planning tools (Schéma d'Aménagement et de Gestion de l'Eau -SAGE, Schéma de Cohérence Territoriaux -ScoT, etc.) because of their long-term scope.

Anticipation through complex thinking (Morin 1990), based on the principle of a future made up of several possible futures (or "futuribles" according to de Jouvenel (1964)) has thus contributed to the emergence and generalization of la Prospective. La Prospective can be defined as an approach (Godet 1977;Godet 1986) or a posture (Berger 1958), including foresights studies, which "consists of gathering elements of appreciation, whether or not quantified, concerning the future, the aim of which is to make it possible to make decisions which will enable the said future to be more in line with our preferences than if there had not been this prospective insight" (Hatem et al. 1993). While this definition refers to a baseline (successfully conforming to something), the plurality of possible futures gives it an eminently polysemic character.

And then, geography got involved... both through this book, for example, which questions the baseline notion, and through approaches and methods designed to take into account the spatial dimension in the construction of these visions of the future. Territorial foresight (Delamarre 2002;Loinger 2004), geoprospectivve (Voiron 2006;Gourmelon et al. 2012;Emsellem et al. 2012), and prospective modeling (Houet 2006;Houet et al. 2011) are all concepts and methods that have contributed to refining, or even transposing, this baseline notion in geography or ecology (Albert et al. 2020), but also to multiplying it.

This chapter attempts to shed some light, probably non-exhaustive, on the various meanings that the notion of a baseline can have in geoprospective. While the particle "geo" is the prerogative of geographers, it has no other ambition than to be able to integrate the spatial dimension in all its complexity in prospective. Indeed, while the multidisciplinary character is intrinsic to prospective, i.e. taking into account social, economic, historical, cultural, demographic, political dimensions, etc., the geographical dimension was only used until the 2000s as a cartographic medium to represent future scenarios. Geoprospective is distinguished by the integration of spatial processes resulting from nature-society interactions (neighborhood, inertia, multi-scalar relationships) to refine the location of future land use and/or landscape changes. Even if spatial simulation models are used to produce scenarios, a common approach used to explore a wide variety of possible futures consists of implementing, in a first step, participatory methods intended for the construction of narratives and which will, in a second step, feed spatial simulation models intended to produce cartographic representations of them (Houet et al. 2016a;Houet et al. 2017). As the spatial dimension can be integrated at all stages of scenario construction (Houet et al. 2010), this chapter aims to illustrate, through examples, the declensions of the notion of a baseline in geoprospective.

The construction of prospective scenarios is based on three stages (Godet 1986): (1) the phase of construction for the knowledge base necessary and shared for the construction of scenarios (Poux 2003), (2) the scenarios themselves made up of narratives and images of the future, and (3) the action phase during which quantified elements of appreciation are provided in order to be able to make decisions, define a strategy. Four meanings of the notion of a baseline can be defined in geoprospective:

The first occurs during the construction phase of the knowledge base, which must be shared by all the people participating in the prospective exercise. Thus, even if the points of view and objectives diverge, the knowledge base constitutes a common baseline.

The second meaning concerns the scenario construction phase. It refers to the notion of validation, in particular of the methods used for their construction, in order to provide supporting elements intended to reinforce the confidence that the actors will ultimately have in these scenarios.

The last two are part of the action phase: they can be used to evaluate, in an exploratory way, the impacts of these scenarios in relation to the initial situation (the current one), but also to define an objective to be reached in order to define the actions to be implemented.

The baseline, as a shared and objective knowledge base

The definition of a shared knowledge base refers intrinsically to the first part of this book, "Defining baselines". In prospective, it is a matter of defining the current state, past dynamics, systemic functioning (driving and dependent variables and their causal relationships), projects and seeds of change in the system being studied. As soon as this system is assimilated to a territory, the spatial dimension can be integrated via multiple geographic methods: remote sensing, geostatistics, participatory methods (social surveys, participatory mapping, for example), modeling of complex systems... Hatem (1993), Piveteau (1995) and Poux (2003) have identified one of the main limitations of a prospective exercise: the tyranny of received ideas. Very often, participants have fixed ideas about certain landscape evolutions and their explanatory factors, the result of their personal experiences and perceptions. For example, while the closure of mountain agropastoral landscapes is well known, the areas concerned and the rates of progression of encroachment and reforestation may be largely underestimated (Houet et al. 2012). Indeed, between 1990 and 2006, the Corine Land Cover database detected almost no change in land uses in the Pyrenees, whereas, using higher spatial and temporal resolution remote sensing data, clear changes were visible between the eastern and western Pyrenees. Similarly, using aerial photographs, it was shown that the Vicdessos valley has been experiencing since the 2000s a process of encroachment and afforestation as rapid as the slopes or valley bottoms during their peak rate after World War II (in the order of 50 to 60 ha / year) (Fig. 1). These received ideas may also have a time frame that does not match the time horizon of the prospective exercise. This may cause bias in the perception of certain practices. For example, slash-and-burn is now considered a cultural practice, part of the pastoral heritage of the Pyrenees, and should be given special attention in the future. Galop et al (2011) were able to demonstrate, using palynological data, that the appearance of mountain fires is posterior to the dynamics of grazing in the Vicdessos valley. In the 1930s and 1950s, slash-andburn appeared to be an adaptive practice to fight against encroachment following the decline in pastoral activity that began at the end of the 19th century. This knowledge makes it possible to envisage the non-maintenance of these practices in certain scenarios, since they have not always existed. Similarly, the oral knowledge shared during participatory meetings on the former uses (pastoral pressure) of these summer pastures, also made it possible to consider scenarios of abandoning certain summer pastures to increase pastoral pressure on others (Houet et al. 2017) (Fig. 1). While the divergence of viewpoints is essential to consider highly contrasting scenarios (to fight or not to fight against land abandonment), it must reflect the stakes for the local actors involved and not be dismissed by the tyranny of received ideas. Thus, this knowledge base necessary for the construction of scenarios constitutes a tangible and shared baseline.

The baseline, a way to improve confidence in scenarios

The knowledge provided by scenarios must be used with confidence by local actors to establish their action plan. Although prospective does not aim to predict, it is the plurality of possible futures that will make it possible to define management and land-use strategies that are less bad than if there had not been this insight into the future. But then, how can scenarios be verified and validated, since the future cannot be validated on the one hand, and since the paradigm of foresight is opposed to that of prediction? This dilemma is particularly marked when modeling tools are used to simulate prospective scenarios.

This confidence is therefore focused on demonstrating that the methods and tools mobilized are working "as they should" or as predicted by the scenarios (as a set of parameters) and not on validating the results as such. In order to validate a prospective exercise, Piveteau (1995) proposes to check whether four principles are verified: relevance, transparency, plausibility and coherence.

Transposed to geoprospective, they question the use of (spatial) models in prospective (Houet, 2015) whether they are cellular automata, multi-agent systems or other modeling platforms. These tools are more and more commonly used to simulate scenarios of land use and land cover changes. "Validation" is becoming more complicated and can no longer be summarized in a single performance indicator (Fig. 2) -The relevance is to justify the choice of a model by an analysis of the literature and/or a comparative study of existing models. The aim is to demonstrate its ability to simulate landscape changes that make sense for the territory or the issues studied (e.g. crop rotations, urban sprawl, etc.) in terms of both their spatial representation and their temporal dynamics, and even the underlying decision-making processes.

-Respect for the principle of transparency is demonstrated by the ability of the user to understand and explain the functioning of the model used. The aim is to avoid the "black box" effect which, if presented in this way to local actors and other participants in the prospective exercise, can sow doubt, mistrust, or even constitute an excuse to reject all the results.

-Consistency must allow for demonstrating that the model is able to simulate processes or trajectories envisaged by the scenarios. Unit, integration or sensitivity tests can thus demonstrate that new spatio-temporal processes can be simulated, in coherence with other existing or new processes.

-Plausibility is part of a "classic" model validation logic, where the predictive power of the model is evaluated through specific indicators, used in isolation or combined (Paegelow et al. 2014). It is then a question of carrying out a simulation on a past period and comparing it with an observed situation.

Compliance with these four principles is fundamental because, while a model can perfectly meet the plausibility principle by simulating a past trajectory perfectly, its calibration and the parameters it uses can make it unsuitable for simulating scenarios that are at odds with past trends (Houet et al. 2016b). Moreover, let us also recall that the plausibility of simulations depends on the plausibility of scenarios, which must be checked beforehand. A model, once validated, can in any case plausibly simulate a completely inconsistent scenario.

The baseline for the exploratory evaluation

Prospective is intrinsically based on a plurality of possible futures. Knowledge about the future therefore comes from the multitude of situations, desired or not, and from their comparison. The analysis of future changes in land use and land cover patterns allows us to evaluate the impacts (positive or negative) on the environment or ecosystem services, for example. The comparison of future states is therefore made in relation to a baseline situation, often assimilated either to the current situation or to another scenario, called the baseline scenario.

A classical approach therefore amounts to comparing the future image resulting from a trend scenario (of the "what if nothing changes" type or integrating future elements whose occurrence is certain) or not with the image of the present situation. This allows, for instance, to quantitatively assess the evolution of landscape closure in the mountains (Vacquié et al. 2015;Houet et al. 2015) (examples in Figure 7.3). It is then possible to assess the impacts of these changes on hydrology (Sczcypta et al. 2015) or even on gravity risks (Bernardie et al. 2021). The advantage of using modeling tools for this assessment is that it is possible to distinguish between the part attributed to climate change on the one hand, and the part linked to anthropogenic activities (or lack of activities) causing a change in the landscape on the other. Whatever the baseline considered, the present situation or a future situation, this approach is fundamentally exploratory aiming at evaluating what would happen / what would be gained if...

The baseline as an objective to be reached

As soon as the scenarios are normative, i.e., starting from a future to be achieved (or avoided), the future becomes an objective, a baseline to be achieved. Any deviation from the desired trajectory can then constitute a warning signal of the ineffectiveness of the policies at work. Nevertheless, we must also take into account the potential inertia of the socio-ecological system with respect to the effects of the measures at work, which may not be immediately perceptible. The latest IPCC scenarios fall rather into this category of scenarios: the description of the "Representative Concentration Pathways" (RCP) defines four trajectories of greenhouse gas emissions and concentrations resulting from a multitude of possible socio-economic and technological scenarios. However, regardless of macroeconomic, demographic or other assumptions, if the situation is close to a pessimistic trajectory (RCP 6.0 or 8.5), it will simply reflect the failure of regional, national or international policies.

This type of approach is very rare in geoprospective because the backward construction of spatio-temporal landscape trajectories from a future goal to the present situation remains very challenging. Brunner et al (2016) propose an original and efficient multi-agent system modeling approach for this type of approach. However, while it clearly has the merit of existing, this type of modeling seeks a location that minimizes land use conflicts resulting in an often "direct" trajectory between two dates. This type of optimization or equilibrium search method makes it difficult to model a bifurcation of the socio-ecological system (trajectory from a neoliberal use model to an agroecological model, for example).

Sometimes, the interest lies not in the landscape trajectory, but in the retrospective identification of the means to be implemented to achieve this landscape, or the errors to be avoided (lack of interventionism). For example, the Rennes agglomeration has created the concept of "urban fields" in its Schéma de Cohérence Territorial (Territorial Coherence Scheme). This zoning makes it possible to protect agricultural land, located in the immediate vicinity of Rennes and largely under pressure from urbanization, which has been made unbuildable in the Local Urban Plans of the municipalities concerned. The goal is to preserve the landscape qualities, the ecological environments of interest, and support development by structuring commuting and linking recreational areas. This would not have been possible without having first identified the objective of implementing a concrete green belt and pursuing development as an "Archipelago City".

Whether it constitutes a monitoring indicator in relation to a "desired trajectory", or a means of defining the regulations or actions to be implemented to achieve a territorial objective, the future in the normative sense thus constitutes a particularly useful baseline for present action.

Conclusion

The notion of a baseline in geoprospective thus has a multitude of possible meanings, summarized in Figure 7.4 and taking up the three meanings defined in the introduction. Globally, we can distinguish between an "observed and shared" baseline (construction of the knowledge base), a baseline "made explicit" by modeling and finally a "desired" baseline linked to the future. Most of these notions refer to aspects of scientific, rigorous and objective methods. In this case, the baseline is not called into question, such as the idea of the presence of the bear mentioned by the author in the general introduction to this work. It is essentially a starting point, relative and subjective, of the order of the sensitive, but which, once compared to the various possibilities that the future represents, brings a new, objective and quantified light.

In fact, he mentions three reasons that may call into question the idea of seeing a bear. Firstly, that it may be implausible and should not be considered. In this example, implausibility is only a human concept, or even a manipulation or a simple oversight. The knowledge of history is thus fundamental to contradict this first reason, because it is the means to fight against the tyranny of the received ideas, mandatory to any prospective.

The second reason concerns the position between science and the sensitive. It is a state of affairs, I myself have long felt a bit schizophrenic: on the one hand, divided between the duty of preserving that a scientist must have when he leads and animates a participatory foresight exercise, where only the opinion and the desires of the participants must be taken into account to hope for a collective strategy (they would certainly not adhere to the opinion of a scholar foreign to their territory proclaiming to them what is good or bad); and on the other hand, that of the scientist activist having to incite a more sustainable development or to alert on the urgency of acting... Nevertheless, being aware of such a pathology allows us to take a step back, to avoid being the reason, as a scientist, for a possible failure of a prospective. It is clear that, on the part of the participants this time, this type of exercise has a kind of medicinal virtue: when we talk about the future, people who no longer talk to each other start to discuss again. Current tensions are, for the duration of a meeting, put aside for a while. The exploration of the future (carried out with rigor and method) desecrates positions of principle and divergence because the future intrinsically evokes a common good and a collective interest. This is what geoprospective is all about: at the beginning, the opinions and points of view on the issue of a territory illustrate the divergences of the stakeholders; the scenarios allow for the emergence of ideas, of desirable or undesirable futures; finally, the knowledge on the future allows a convergence of interests and even the definition of a consensual strategy for the development and management of the space. Finally, the third reason concerns the Anthropocene itself, where human action would already be too important and nature would no longer exist. Without getting into this philosophical or even ideological debate where Nature and Society are opposed by definition but both deserve a place on this Earth, would it not be simpler to consider this as one scenario among others? And if the challenge consisted of making a prospective of the Anthropocene? ... and then I realize. This has already been done by Meadows et al (1972). So what went wrong? Probably, the collective acculturation of this famous concept of sustainable development, the acceptance of the failure of a development model, the questioning of a carefree generation? Still, without this, the seeds of change would not have been sown. Today, the future generation is ready, but it is up to it to decide where it wants to go.

Figure 7 . 1 .

 71 Figure 7.1. Illustration of the contribution of multidisciplinary approaches to establishing an objective and shared knowledge base using perceptual elements (landscape photographs) and figures (maps and graphs). The example is that of the Haut-Vicdessos valley (and the Bassiès valley) and the closure of the landscape (fromGalop et al. 2011 and Houet et al. 2012)

Figure 7 . 2 :

 72 Figure 7.2: Illustration of the methods that can be used in modeling to respect the four principles of validation of a foresight approach.

Figure 7 . 3 .

 73 Figure 7.3. Examples of exploratory scenarios of environmental closure in the Upper Vicdessos Valley in 2080 (top) for two pasture management strategies: (a) maintaining low pastoral pressure everywhere and (b) abandoning the least favorable summer pastures) (from Houet et al. 2015) -and their variation at a finer scale for levels of (A) strong, (B) medium or (C) zero pastoral pressure in Bassiès (from Sczcypta et al. 2015).

Figure 7 . 4 .

 74 Figure 7.4. The different variations of the notion of baselines in geoprospective according to the stages of construction of spatialized prospective scenarios

In France these are called PPRIs, the acronym for Plan de Prévention du Risque Inondation.