Synthèse et copolymérisation avec l'acrylamide de macromonomères d'acrylate de dodécyle

Graft copolymers of well-defined structure and composition were prepared by radical copolymerization of acrylamide and poly(dodecyl acrylate) macromonomers. The macromonomers were prepared by telomerization of dodecyl acrylate in the presence of 2-mercaptoethanol as a transfer agent, followed by reaction with acryloyl chloride. Poly(dodecyl acrylate) macromonomers with M _n = 1100, 1100, 2200 and 4600 were synthesized. The kinetics of the radical telomerization of dodecyl acrylate with 2-mercaptoethanol and AIBN was studied at 66°C in THF. Under these conditions we obtained the transfer constant C_T = 0,9. The graft copolymerization of acrylamide with the poly(dodecyl acrylate) macromonomer was carried out in the presence of the transfer agent C₆F₁₃C₂H₄SH. If C₀ = [AIBN]/[Acrylamide] = 0,01 and R₀ = [C₆F₁₃C₂H₄SH]/[Acrylamide] = 0,01, for acrylamide a DP _n = 160 was obtained in all cases, for the macromonomer of M _n = 1100 a DP _n = 2,5, and for the macromonomer of M _n > 1100 a DP_n = 1.     

Incréments d'indice de réfraction de polymères en solution: Étude des lois de mélange. Influence de la masse moléculaire et de la structure

The variation of the refractive index increment (dn/dc) with the molecular weight and the structure of series of linear and branched well-defined polystyrenes dissolved in benzene was studied. Testing the Lorenz-Lorentz and Onsager-Böttcher mixture rules, we were able to show that:

• 1 Below a critical molecular weight of about 2·10⁴, the linear correlation dn/dc=f(1/M_n) is well explained by the influence of chemical heterogeneities included in the polymer chain (end-groups, branching points etc.).
• 2 These rules do not account for specific polymer-solvent interactions and are not quite rigorous.
• 3 The variations of (dn/dc) and the partial specific volume of the polymer, v?_p, observed already for molecular weights higher than 2·10⁴ are accompagnied by a change in the partial specific refractivity. These effects are related to the influence of intramolecular segment density in the interior of the linear or branched coil.

A homologous series of polyoxyethylene-glycols (α-hydro-ω-hydroxypoly(oxyethylene)s) in benzene presents the same behaviour.     

Synthèse de l'acide 2-acrylamido 2-méthylpropanoïque et copolymérisation avec l'acrylamide

The synthesis of 2-acrylamido-2-methylpropanoic acid (2A2MPA) was carried out starting from 2-methylpropanoic acid. Copolymerizations of the 2A2MPA salt (2A2MPANa, monomer A) with acrylamide (AM, monomer B) were investigated using K₂S₂O₈ as initiator. They were terminated before reaching 15% conversion. A range of feed compositions was selected (2A2MPANa increasing from 10 to 100 mol-%) and the compositions of the copolymers obtained were assessed through ¹³C NMR. The reactivity ratios for the couple A, B were determined as r_A = 0,76 and r_B = 1,06. One additional copolymerization was allowed to reach 100% conversion, and the final copolymer showed interesting drag reduction properties.     

Amorceurs radicalaires fonctionnels, 2. Macroinitiateurs à partir de l'α-hydrogeno-ω-hydroxypoly(oxyéthylène) et des acides tert-butyldioxycarbonylbenzoïques

Modified polystyrenes were obtained by free radical polymerization of styrene using the macroinitiators α-tert-butyldioxyterephthaloyl(or phthaloyl)-ωtert-butyldioxyterephthaloyl(or phthaloyl)poly(oxyethylene) ( 3 and 4 ), which were synthetized. To examine the stability of such compounds, thermolysis kinetics of model compounds, OO-tert-butyl O-methyl monoperoxyphthalate ( 6 ) and terephthalate ( 7 ) were studied by differential scanning enthalpimetry. Suspension polymerization of styrene applying the industrial method, showed that the macroinitiator is able to initiate the process. A polystyrene containing up to 4% by weight oxyethylene units was obtained.     

Dégradation de polybutadiènes par métathèse avec l'hexène-3 dioate de diméthyle

Studies of metathetic degradation of polybutadienes containing 70 to 80% of 2-butene-1,4-diyl units ( 1 ) in presence of dimethyl 3-hexenedioate ( 2 ) were carried out applying WCl₆/Me₄Sn as catalyst and r = [ 2 ]/[ 1 ] values varying between 0,4 and 0,01. The degradation was followed by steric exclusion chromatography, and the structural composition of degraded products was determined by ¹H NMR. For r = 0,2, the degradation by cross metathesis between 1 and 2 , leading to α,ω-bifunctionalized “prepolymers”, is superimposed by degradation via intramolecular metathesis and cationic cyclization of 1 units. Cationic side reactions (cyclization) are minimized by addition of ethyl acetate to the catalytic system.     

Application de la réaction de métathèse à la synthèse de prépolymères α,ω-bifonctionnels, 2. Etude de possibilitiés d'application à la synthèse de prépolymères α,ω-dichlorés

The capability of chloroalkenes to undergo cometathesis with alkenes was investigated with the intention to check the possibility of applying the principle of the synthesis of α,omega;-difunctional polybutadienes to α,omega;-dichloropolybutadienes. The results obtained from the analysis of the reaction products resulting from 1,6-dichloro-3-hexene ( 1 )/4-octene ( 2 ) systems and WCl₆/EtAlCl₂ were compared with those obtained from 1-chloro-3-hexene ( 8 ) alone, 1 /1,5-cyclooctadiène ( 13 ), 5-chloro-1-pentene ( 6 )/ 2 , and 1,4-dichloro-2-butene ( 10 )/ 2 systems in the presence of WCl₆/EtAlCl₂. It was found that it is possible to apply the synthetic principle to α,omega;-bis-(δ-chloroalkenyl)polybutadienes.     

Synthèse de macromères à base de chlorures de vinyle et de vinylidène au moyen de télomères

New macromers 4, 8, and 10, containing ester, alcohol, or acid functions, were prepared starting with vinyl chloride (CV) or vinylidene dichloride (CV₂). The telomer 1, resulting from CV₂ and CCI₄ was telomerized with allyl acetate and the product was transformed into the acrylate 4 by hydrolysis of the reaction product and subsequent esterification. Macromers 8 and 10 were prepared from CV by radical telomerization with thioglycolic acid (7) and 2-mercaptoethanol (9), respectively. Reactive double bonds were introduced into these macromers by reaction with acrylic acid, Vinyl chloroformate, methacryloyl chloride, or 2,3 -epoxypropyle methacrylate, leading to new macromers 12, 13, 14, and 15, respectively.     

Synthèse et caractérisation de copolymères coordinés par des sels métalliques

The anionic block copolymerisation of isoprene and 2-vinylpyridine (2VP) followed by a coordination with iron (III) chloride, leads to thermoreversibly crosslinked copolymers. These copolymers are character+ed by a low polydispersity (M?_w/M?_w≈1,1) between the coordination nodules of poly(2-vinylpyridine). The study of the swelling ratio at the equilibrium in benzene shows that such a polymeric network does not reach the equilibrium state expected from the thermodynamic analysis of the system. The presence of 2VP in the copolymer induces a screening effect which prevents the solvent diffusion through the polyisoprene network.     

Synthèse de cotélomères photoréticulables, 6. Utilisation de cotélomères biséquencés

Photocrosslinkable block cotelomers were synthesized in three steps. In the first step a monomer M₁ was telomerized with carbon tetrachloride or chloroform, in the second step a monomer M₂ with the resulting macrotelogen, and in the third step the hydroxyl groups were esterified by cinnamic acid or acrylic acid. These reactions were carried out with ethyl acrylate (M₁)/CCl₄ by redox catalysis and subsequently with vinyl acetate (M₂) by free radical initiation, or with vinyl acetate (M₁)/CHCl₃ by free radical initiation and subsequently with isoprene (M₂) by redox catalysis, or with 2-hydroxyethyl acrylate (M₁)/CCl₄ by redox catalysis, and subsequently with isoprene (M₂) by redox catalysis.     

Application de la réaction de métathèse à la synthèse de prépolymères α,ω-bifonctionnels. 1: Cométathèse entre le cyclooctadiène-1,5 et l'hexène-3 dioate de diméthyle

α,ω-Dimethoxycarbonyl substituted polyenes were synthesized by co-metathesis between 1,5-cyclooctadiene ( 1 ) and dimethyl 3-hexenedioate ( 2 ) by use of the catalytic system WCl₆/Sn(CH₃)₄. The ability of 2 for co-metathesis with 1 was proved by determination of the distribution of low molecular weight products in terms of reaction time and 2/1 mole ratio. For these studies, high values of 2/1 ratios (0,5–4) were chosen in order to obtain lowest molecular weight co-metathesis products ( 3b–3e ). Metathesis involved preferentially the double bonds in the neighbourhood of the ester groups. At lower values of the 2/1 ratio (0,012–0,061) α,ω-difunctional prepolymers ( 3i ) were synthesized.     

Synthèse de polystyrènes chlorométhylés renfermant des radicaux tétrathiafulvalénylphénoxyméthyles

In order to study the influence of the nature of the moiety bearing a tetrathiafulvalenyl group in the polymers upon the microlithographic properties of resists, poly(p-chloromethylstyrene)s and poly(styrene-co-p-chloromethylstyrene)s containing the 4-tetrathiafulvalenylphenoxymethyl group with a variety of controlled molecular weights and molecular weight distributions were studied. The copolymers were all prepared by reaction of poly(4-vinylbenzyl chloride) with potassium 4-tetrathiafulvalenylphenolate ( 3 ). Without exception, the resulting poly[p-chloromethylstyrene-co-p-(tetrathiafulvalenylphenoxymethyl)styrene]s are highly insoluble. However, by reaction of potassium 4-tetrathiafulvalenylphenolate with poly(styrene-co-p-chloromethylstyrene) soluble copolymers could be prepared.     

Use of Original ω‐Perfluorinated Dithioesters for the Synthesis of Well‐Controlled Polymers by Reversible Addition‐Fragmentation Chain Transfer (RAFT)

A series of five fluorinated dithioesters PhC(S)SRCH₂C_nF_2n+1 (where R represents an activating spacer and n = 6 or 8) was obtained in fair to high yields (57–88%). These transfer agents were successfully used in reversible addition‐fragmentation transfer (RAFT) of styrene (S), methyl methacrylate (MMA), ethyl acrylate (EA) and 1,3‐butadiene. Well‐chosen fluorinated dithioesters were able to lead to a good control of the radical polymerization of these monomers (i.e., molar masses of the produced polymers increased linearly with the monomer conversion and the polydispersity indexes ranging between 1.1 and 1.6 remained low). The relationship between the structures of the dithioesters and the living behavior of the radical polymerization of these above monomers is discussed and it is shown that the nature of the R group influences the living behavior from different contributions to radical stabilization. Furthermore, the RAFT process also yielded PMMA‐b‐PS and PEA‐b‐PS block copolymers bearing a fluorinated moiety.     

Etude de la structure ramifiée du polyéthylène basse densité par viscosité et diffusion de la lumière de fractions issues de la chromatographie d'exclusion gpc

Fractions of high density polyethylene (PEhd) and low density polyethylene (PEld) obtained from gel permeation chromatography were studied by viscometry and light scattering. The variations of the intrinsic viscosity [η], the molecular weight M?_w, and the radius of gyration R_g for PEhd and PEld were compared with one another and the relationships [η] vs M and R_g vs. M for PEhd were established. The dependence of structural parameters g = (R_g²)_branch/(R_g²)_linear and g′ = [η]_branch/[η]_linear on the molecular weight was determined for three samples of PEld.     

Oligomères amphiphiles obtenus par voie radicalaire, 1. Synthèse et caractérisation d'oligomères de l'acide acrylique à extrémité dodécylthio

Oligomeric emulsifiers were prepared by the technique described by Roe, with special care of composition and molecular weight. Acrylic acid was polymerized in 2-propanol with lauroyl peroxide as initiator in the presence (at various ratios) of 1-dodecanethiol ( 8 ) as transfer agent to control the chain length. A good agreement was found between the various methods used for kinetic determination and oligomer characterization (¹H NMR, sulfur analysis, vapor pressure osmometry, acidimetry, GPC). Values of k_pk_t^-1/2, transfer constants for thiol 8 and solvent, nature of chain ends, polydispersity, and molecular weight were determined. Polymer fractionation was successfully performed using different solvents for recovery.     

Cinétiques de télomérisation, 7. Calcul de k/kTe en polymérisation radicalaire de divers monomères

In contrast to the usual method of determination of the principle ratio in radical polymerization, k/k_Te, which is based on the comparison of the rate of polymerization with the concentration of initiator, a method was used consisting in the representation of log_e([M]₀/[M]) versus (1 ? e^?kd^t/2). The results obtained with styrene, vinyl acetate, acrylic acid, methacrylic acid, and 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl acrylate ( 1 ) were found to be in good agreement with those already obtained by the other method.     

Etude de la synthèse et de la microstructure du polyallylbenzène

Poly(allylbenzene)s were synthetised by Ziegler-Natta catalysts: {VCl₃ + Al[CH₂CH(CH₃)₂]₃} and {TiCl₄ + Al[CH₂CH(CH₃)₂]₃}. Two different polymers were obtained. Examination of their microstructures by IR and ¹H¹³C NMR spectroscopy suggests that one of the polymerization mechanisms proceeds via isomerization of allylbenzene.     

Synthèse et caractérisation de polystyrènes siliciés

Poly(p-trimethylsiloxystyrene) (1a) , poly[p-(tert-butyldimethylsiloxy)styrene] (1b) , poly[p-(trimethylsiloxy)-α-methylstyrene] (1c) , poly[p-(tert-butyldimethylsiloxy)-α-methylstyrene) (1d) and poly{p-[2-(tert-butyldimethylsiloxy)ethyl]styrene]} (1e) were prepared by free-radical or cationic polymerization of the corresponding monomers. Poly{[p-[2(trimethylsiloxy)ethyl]styrene]-co-[p-(2-hydroxyethyl)styrene]} (2a) was synthetized by anionic polymerization of the corresponding trimethylsilylated monomer, followed by acid hydrolysis of the resulting polymer. Poly{[p-[2-(trimethylsiloxy)ethyl]styrene]-co-[p-(tert-butoxycarbonyloxy)styrene]} (2b) were prepared by free-radical polymerization of the corresponding monomers.     

Synthèse de polyglutarimides à partir de PMMA,de la cyclohexylamine et de la méthylamine, 3 Etude du mécanisme d'imidification sur des modèles macromoléculaires

In order to check the mechanism of intramolecular cyclization to obtain glutarimide rings, we have prepared various homo and copolymers: homo N‐methyl‐ and homo N‐cyclohexylmethacrylamide and the corresponding copolymers with MMA and MAA. This first study showed that methacrylamides are less reactive than other methacrylic derivatives as shown by the r₁ and r₂ values of MMA and N‐cyclohexylmethacrylamide. The cyclization at 250°C in xylene proves that in the case of N‐cyclohexyl derivatives, the following reactivity is obtained: amide‐acid ≫ amide‐amide ≫ amide‐ester. On the contrary with N‐methyl derivatives, the reactivity of each complex is higher although amide‐acid remains the more reactive. The steric hindrance may account for this phenomenon.     

Synthèse de polysiloxanes acyloxyméthylés par réaction des acides acétique,benzoïque et méthacrylique,en présence de triéthylamine,sur des polysiloxanes chlorométhylés, 2. Etude de la réaction sur trisiloxane et tétrasiloxane modèles

The reaction of acetic, benzoic and methacrylic acids with 3-chloromethylheptamethyltrisiloxane and 3,5-bis(chloromethyl)octamethyltetrasiloxane in toluene in the presence of triethylamine was studied. Beside the expected transformation of oxy(chloromethyl)methylsilanediyle ( A ) units into oxy(acyloxymethyl)methylsilanediyle ( C ) units, redistributions of A , C and trimethylsilyl/oxytrimethylsilyl (M) were observed. The conversion versus time curves of distribution of the former oligomers (mole fractions of trisiloxanes: F₁ = m_{M- X -M} = m_{M- A -M} + m_{M- C -M} and tetrasiloxanes: F₂ = m_{M- X - X -M} = m_{M- A - A -M} + m_{M- A - C -M} + m_{M- C - C -M}) were followed. The reaction rates were not only controlled by the acid used but also by the starting oligosiloxane (trisiloxane or tetrasiloxane). The distributions of the homogeneous and heterogeneous oligomers seem to result from controlled combinations of A , C and M according to orientations of cleavages and to relative affinities of RCOOH/NEt₃ towards various siloxanes. For the total conversions the mole fractions F₁ and F₂ fit with those calculated by a law based on a hazard combination of C and M. This result may be explained by the compensation of electronic and steric factors.     

Synthèse et copolymérisation d'acrylamides comportant le groupement dihydroxyphosphoryloxyalkyle

ω-Aminoalkyl dihydrogen phosphates 5a–c , 7 and 9 were obtained in a simple and reproducible fashion by O-phosphorylation of the corresponding aminoalcohols with ClPO₃H₂ generated in situ by controlled hydrolysis of POCl₃. Reaction of these phosphates with acrylic or methacrylic anhydride in water/THF mixture afforded a series of new acrylic monomers ( 11a–h ) bearing a phosphoryl group. Inverted emulsion copolymerization of the latter with the hydrophilic comonomers N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]acryl- or methacrylamide ( 12a or 12b ) and with the cross-linker N,N′-methylenediacrylamide ( 13 ) afforded various gels in the form of spherical beads. Preliminary experiments showed that some of these copolymers could be efficiently used as stationary phases for the separation of proteins by ion-exchange chromatography.