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.     

Copolymérisation de la N-acryloyl-L-valine et de la N-acryloyl-L-phénylalanine avec l'acrylamide

The synthesis of N-acryloyl-L -valine (NAVAL) and N-acryloyl-L -phenylalanine (NAPHE) have been carried out from L-valine and L-phenylalanine. The chiral compounds have been characterized by ¹H and ¹³C nuclear magnetic resonance (NMR) spectroscopy, infrared (IR) spectroscopy and polarimetry. The copolymerization of NAVAL salt, (NAVAL Na, monomer A) or NAPHE salt (NAPHENa, monomer A′) with acrylamide (AM, monomer B) has been investigated using K₂S₂O₈ as initiator, over a range of the feed compositions for NAVALNa (or NAPHENa) from 10 to 100 mol-%. The compositions of copolymers have been systematically assessed through ¹³C NMR. The reactivity ratios for the couple A, B were determined as r_A = 0,67, r_B = 0,91 and for the couple A′, B they have been evaluated to be: r_A′ = 0,40, r_B = 0,91. The azeotropic composition is located at 21 mol-% for the couple A, B and at 13 mol-% for the couple A′, B. Drag reduction effects are obtained with these polymers.     

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.     

Terpolymérisation acrylonitrile-styrène-acrylate de méthyle, 4. Copolymérisation en emulsion styrène-acrylate de méthyle en réacteur fermé (batch) en présence de persulfate de potassium

To improve the knowledge of emulsion copolymerization of monomers both swelling their copolymers, but which are of quite different polarity (water solubility), a series of styrene (S)/methyl acrylate (MeA) copolymerizations was carried out in batch at 50°C with potassium persulfate as initiator. The overall rates of copolymerization increase with the amount of MeA in the monomer feed. Copolymer composition follows the usual copolymerization equation if bulk/solution reactivity ratios (r_ij) and monomer partition between aqueous and organic phase are taken into account (simulation). However, accurate kinetic data at low conversion (gas chromatography) put in evidence an enhanced polymerization of the more hydrophilic monomer (MeA), which can be attributed to polymerization in the water phase. Particle sizes increase with conversion and tend to a limiting value, the higher the MeA content is. Particle number (N_p), which is practically constant with conversion of S homopolymerization, tends to increase with MeA content as polymerization proceeds. This trend is enhanced if the emulsifier (sodium dodecanesulfonate, SDS) concentration is increased. Overall propagation rate constants were estimated as function of the experimental conditions and monomer concentration within the particles. From kinetic data (rate of polymerization) and N_p, it was found that the average number of radicals per particle, ñ, remains close to 0,5. It was then possible considering S(k_p = 125 1 · mol^?1 · s^?1) as a standard monomer, to estimate the polymerization rate constant for MeA (335 1 · mol^?1 · s^?1). Since adsorption of emulsifier was shown to be closely related to particle surface composition, the specific area A_s of SDS was measured on latices at various conversions and initial monomer feeds. As conversions increases, the particle surface appears to be richer and richer in MeA, which corresponds to a particle structuration. Strong and weak acid group titration is also in quite good agreement with the colloidal behaviour.     

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.     

Poly{[(Chloro-2 éathyl)-4 phéanyl]-1 éathylène}: Synthèse,caractérisations,dégradation thermique et modifications chimiques

Poly{1-[4-(2-chloroethyl)phenyl]ethylene} ( 3 ) was synthesized by bulk polymerization of 4-(2-chloroethyl)styrene ( 6 ) in two steps from commercial products. The polymer was characterized by means of GPC (weight-average molecular weight M?_w = 85 000 and number-average molecular weight M?_n = 63 500), ¹H NMR and ¹³C NMR spectroscopy. The first stage of thermal degradation begins at 290°C and ends at about 410°C. The overall activation energy was calculated to be 43 kcal · mol^?1 (180 kJ · mol^?1). The solid residue was crosslinked and insoluble. The volatile products, identified by gas chromatography-mass spectroscopy (GC-MS), were chiefly hydrogen chloride, dichloromethane and monomer. In a strongly basic medium, nucleophilic substitution of chlorine was achieved without elimination.     

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 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.     

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.     

Etude de la réaction de télomérisation d'un monomère tensioactif anionique

The synthesis of a new anionic polymerizable surfactant is described. It is obtained by reaction between methacryloyl chloride and 5-phenyl-1-pentanol. In a last step, the aromatic group is alkylated with succinic anhydride in order to obtain an ionic group. All products were characterized by ¹H nuclear magnetic resonance and the transfer constant C_T with C₈H₁₇C₂H₄SH and the ratio k_p²/k_t were determined. C_T is in agreement with that of classical acrylates whereas k_p²/k_t is lower because of the long methacryloyl chain which reduces the propagation rate.     

Etude de la télomérisation de l'acide acrylique par les mercaptans, 1 Télomérisation de l'acide acrylique par l'acide thioglycolique; Influence de la nature du solvant sur la valeur de la constante de transfert et de kp/√kte

The telomerization of acrylic acid (AA) with thioglycolic acid (TGA) initiated with 2,2′‐azoisobutyronitrile (AIBN) was first investigated in organic medium (THF, 65°C). The kinetic study of this telomerization led to the determination of the TGA transfer constant (C_T = 3.2) and to the ratio k_p/√k_te equal to 0.48 L^1/2·mol^–1/2·s^–1/2. Then, the same study was performed both in aqueous medium and in water/THF mixture in order to investigate the solvent effect on the transfer constant. From these works it is emphasised that the nature of the solvent plays an important role on the kinetics parameters. First, this research underlined an increase of the k_p/√k_te value by raising the water proportion in water/THF mixtures. Then, the kinetic study showed the highest value for the k_p/√k_te constant, equal to 2.48 L^1/2·mol^–1/2·s^–1/2 when the telomerization proceeded in water. Consequently, the value of C_T, which is directly influenced by the k_p/√k_te constant, presented a decrease from C_T = 3.2 in THF to a value equal to 0.5 in water. By this way, the « ideal » case of telomerization (C_T = 1) was reached for a mixture of solvents; 80% water/20% THF (v/v).     

Caractérisation de réactions primaires de dégradation oxydante au cours de l'autoxydation des polyoxyéthylènes à 25°C: Étude en solution aqueuse avee amorçage par radiolyse du solvant. II. Arguments pour un mécanisme monomoléculaire de décomposition des radicaux peroxyles

Cationic copolymerizations of furfural were carried out with several vinyl monomers. No copolymers were obtained with some hydrocarbon comonomers. At low temperatures furfural copolymerized with vinyl ethers selectively through the aldehyde group. On the other hand, deeply-colored copolymers of complex structures were formed at higher temperatures (ca. 0°C). Three typical vinyl ethers (p-tolyl vinyl ether, dihydropyran, and divinyl ether) were selected as comonomers, and their copolymerization behaviour studied in detail. The monomer reactivity ratios for furfural (M₁) and p-tolyl vinyl ether (M₂) were r₁ = 0,15 ± 0,15, r₂ = 0,25 ± 0,05. The furfural (FF) contents were fairly independent of the monomer feeds when dihydropyran (DHP) and divinyl ether (DVE) were used as comonomers: 37–47% for FF-DHP copolymers and 40–50% for FF-DVE copolymers. More than half of the second vinyl groups were consumed in the FF-DVE copolymers indicating the formation of 1,3-dioxane rings as in the case of benzaldehyde-DVE copolymers.     

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.     

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.     

Copolyesteramides, 8. A comparison of substantially alternating 12-oxydodecanoyl/ω-iminoalkanoyl polyesteramides with equivalent random copolymers

The polycondensation of methyl N-(12-hydroxydodecanoyl)-ω-aminoalkanoates (HO(CH₂)₁₁CONH(CH₂)_xCOOCH₃) has been studied as a source of the alternating polyesteramides [O(CH₂)₁₁CONH(CH₂)_xCO]_n, and the properties of the products compared with those of equivalent random copolymers of similar co-unit ratio. Polymerization of the esters with x = 10 and 11 occurred straight-forwardly, giving crystalline products with were distinguishable from the random counterparts by DSC but not by 67 MHz ¹³C NMR. For x = 5 the reaction was complicated by progressive partial elimination of the amide moiety as 6-hexanolactam and by transamidation leading, for the polymer of highest amide content obtained, to an imperfect structure with ca. 76% of the sub-units in alternating arrangement, the remainder being composed of oligoester and diamide units. This deviation from ideality has been elucidated by a study of the ¹³C NMR spectra of a wide range of model compounds which has yielded criteria for the recognition of oligomeric iminohexanoyl units, and by the NMR and MS examination of the products of aminolytic degradation. The results explain the multiple signals found in the ¹³C NMR spectra of the imperfectly alternating polymer (x = 5) and of its random analogues.     

Le poly(α-acétoxystyrène) et les copolymères de l'α-acétoxystyrène avec le styrène et styrènes substitués obtenus par polymérisation thermique. Etude de la microstructure et de la stabilité thermique des polymères

The microstructure of poly(α-acetoxystyrene), prepared from α-acetoxystyrene by bulk thermal polymerization, was studied by ¹H and ¹³C NMR spectroscopy. Anomalies observed in the NMR spectra could be ascribed to fragmentations with formation of benzoxy and acetoxy radicals followed by re-initiation. The thermal degradation of the polymer, resulting in the formation of polyphenylacetylene, rules out certain types of transfer. α-Acetoxystyrene was copolymerized with styrene or substituted styrenes and the NMR study (¹H and ¹³C) was limited to α-acetoxystyrene. The composition of the copolymer could be ascertained by means of the resonances of the quaternary carbons of the aromatic cycle. The copolymers were characterized by viscometry, GPC, and thermal degradation. Their compositions, except that of poly(α-acetoxystyrene-co-styrene) were determined by elemental analysis.     

Etude de la dégradation thermique de deux copolymères réalisés entre l'acrylonitrile ou le méthacrylonitrile et l'α-acétoxyacrylate de méthyle. Analyse thermogravimétrique et chromatographique en phase gazeuse couplée à la spectrométrie de masse

The thermal degradation behaviour of two copolymers poly(acrylonitrile-co-methyl α-acetoxyacrylate) and poly(methacrylonitrile-co-methyl α-acetoxyacrylate) was studied by means of dynamic and isothermal thermogravimetry in the range 246–302°C and gas chromatography/mass spectrometry analysis. The main volatil products are acetic acid and methyl acetate and methanol in minor amounts. There is no monomer from the first copolymer. The global reaction order is zero over a wide range of conversion (α = 0,1 – 0,6), then it is one for α > 0,7, with activation energies of 160,5 and 142,9 kJ ˙ mol^?1, respectively. Some amount of comonomers was found in addition in the case of the second copolymer. The kinetic law may be written as: where A and C are constants for every temperature. The global activation energy was found to be 127,0 kJ ˙ mol^?1. A kinetic model of a one order reaction with a partial auto catalytic character allows a very good fit of the experimental data with the theoretical curves over a wide range of conversion (α = 0,1–0,8).     

Synthèse et polymérisation de monomères acryliques fluorés substitués en position α, 4. Applications à l'α-acétoxyacrylate et à l'α-propionyloxyacrylate de 2-perfluorooctyléthyle

The synthesis of the two monomers 2-perfluorooctylethyl α-acetoxyacrylate ( 1 ) and 2-perfluorooctylethyl α-propionyloxyacrylate ( 2 ) was performed in two steps starting from ethyl pyruvate and 2-perfluorooctylethanol with overall yields of about 56% and 50%, respectively. Transesterification of ethyl pyruvate with the adequate fluorinated alcohol followed by enol acylation gave 1 and 2 , respectively. The kinetic study of polymerization of monomers 1 and 2 , led to the determination of the values of the ratio of the square of the rate constant of propagation over the rate constant of termination k²_p/k_te equal to 9,2 · 10^?3 and 9,1 · 10^?3 L · mol^?1 ·s^?1, respectively, and were compared to those of commercially available fluorinated acrylates and methacrylates.     

Oligomérisation anionique de l'éthylène, 4. Etude cinétique de la réaction amorcée par le complexe sec-butyllithium-tétraméthyléthylènediamine

The oligomerization of ethylene in hexane, initiated by sec-butyllithium (sec-BuLi) complexed with tetramethylethylenediamine (TMEDA) was studied. The half-order reaction in [sec-BuLi-TMEDA] and [PELi-TMEDA] (PELi = (polyethylene)lithium) supports the presence of aggregated dimer species. For the initiation as well as the propagation, a dissociation of these dimers (sec-BuLi-TMEDA)₂ and (PELi-TMEDA)₂ has to be considered, the monomeric form being the only active one. The higher reactivity of sec-BuLi compared to PELi can be explained partly by a secondary carbanionic structure compared to a primary one.     

Volumes spécifiques de polystyrènes en étoile à l'état liquide

Specific volume measurements carried out on linear and star-shaped liquid polystyrene versus the number average molecular weight, M_n scaling between 5000 and 2.10⁶, are in good agreement with a review of the experimental results of others. These results confirm the occurrence of a loss of volume per monomeric unit above a molecular weight of 10000 already observed for polystyrene in solution. We attribute the influence of this specific volume variation against M_n on the thermal dilatometric coefficient α = (1/v)dv/dT and the temperature of vitrous transition. We also attempted to give an explanation for this phenomenon.