Radical Copolymerization Behavior of 2,2‐Dimethyl‐5‐methylene‐1,3‐dioxolan‐4‐one with Common Monomers

Radical copolymerization of 2,2‐dimethyl‐1,3‐dioxolan‐4‐one (DMDO) consisting of a hybrid structure of acrylate and vinyl ether moieties with styrene, methyl methacrylate, and vinyl acetate was examined. The radical copolymerization was carried out without a solvent or in chlorobenzene in the presence of 3 mol‐% of 2,2′‐azoisobutyronitrile at 60°C for 20 h to obtain the copolymers with number‐average molecular weights of 1 400‐700 000 in 27–86% yields. No ring‐opening occurred but vinyl polymerization of DMDO selectively proceeded in the copolymerization. The monomer reactivity ratios were evaluated as r₁ = 6.42, r₂ = 0.08 (M₁, DMDO; M₂, styrene) by the Fineman‐Ross method. The Alfrey‐Price Q‐ and e‐values of DMDO were calculated as 5.97 and –0.13, respectively. Ab initio molecular orbital calculations were carried out to compare the reactivity of DMDO with methyl α‐methoxyacrylate and vinyl ether.     

Cinétiques de télomérisation, 4. Nouvelle méthode de détermination des constantes de transfert en catalyse radicalaire

For the determination of transfer constants C_T to the telogen in telomerization reactions started with free radicals we used three methods. The first one is the method of Mayo, the second one is based on the variation of the conversion degree of telogen to monomer and the last method requires the knowledge of the cumulated number-average degree of polymerization DP _n and monomer conversion α_M of the samples during the reaction. Verifications of the proposed laws are made for methacrylic acid telomerization with CCl₃Br and methyl methacrylate telomerization with benzenethiol as a telogen and 2,2′-azoisobutyronitrile as the initiator at 70°C. The transfer constant to CCl₃Br is ca. 0,03 and that to C₆H₅SH ca. 1,5.     

Multifunctional Poly(vinyl ethers) by Controlled Cationic Polymerisation in a Fluorinated Solvent

The living nature of the cationic polymerisation of butyl vinyl ether (BVE) in the fluorinated solvent 1,1,2‐trichloro trifluoroethane was studied, using the initiating system composed of ethyl aluminium dichloride (EtAlCl₂) as the activator and 1‐butoxyethyl acetate (BEA) as the initiator. BVE homopolymerises in a seemingly living fashion at T ≤ 0°C in the presence of 1,4‐dioxane (DO) as a stabilising Lewis base, although the fluorinated solvent slows down the polymerisation appreciably. Less than quantitative reinitiation has been observed when a second BVE feed was added to the living macrocation at nearly quantitative monomer conversion. The functional monomers 2‐chloroethyl vinyl ether (CLEVE), 3‐cyano‐3‐ethoxycarbonylpropyl vinyl ether (CNEVE) and 1H,1H,2H,2H‐perfluorodecyl vinyl ether (XFDVE) were submitted to polymerisation under the same conditions that allow to achieve a quasi‐living BVE polymerisation. CLEVE gave a homopolymer with relatively narrow molecular‐weight distribution (MWD), while efficient polymerisation of XFDVE was only achieved with BF₃ etherate as the initiator. Copolymerisation of the various functional vinyl ethers with BVE takes place in a more controlled fashion, yielding products with narrow MWD index (M_w/M_w = 1.2–1.35), at moderate functional vinyl ether conversions. Block copolymers could be synthesised from poly(BVE) living macrocations; these are probably characterised by a hybrid structure, consisting of a pure BVE block and a second block of BVE‐functional vinyl ether copolymer.     

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.     

Polymerization of macromonomers, 3. Monomer reactivity ratios in radical copolymerization of poly(tetrahydrofuran) macromonomers with 2-vinylnaphthalene

Methacrylate-terminated poly(tetrahydrofuran) (MA-PTHF) and acrylate-terminated poly-(tetrahydrofuran) (A-PTHF) macromonomers (M₂) were radically copolymerized with 2-vinylnaphthalene (2-VN, M₁). The composition of copolymers was determined by UV spectroscopy taking advantage of the very high absorption coefficient (UV) of the monomeric units of 2-VN in copolymer. The monomer reactivity ratios r₁ and r₂ evaluated are as follows. MA-PTHF: r₁ =1,3 ± 0,21, ± 0,05; A-PTHF: r₁ = 2,5 ± 0,35, r₂ = 0,10 ± 0,05. These reactivity ratios were compared with those in the copolymerizations of 2-VN with the corresponding small monomers and were discussed in terms of polymer (hindering) effect and the concept of equal reactivity of growing chain.     

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.     

Synthesis and characterization of photoconductive polymers, 1. Synthesis of poly[2-(9-carbazolyl)ethyl vinyl ether], poly[2-(9-carbazolyl)ethyl 1-propenyl ether], and their various copolymers with ethyl vinyl ether

2-(9-Carbazolyl)ethyl vinyl ether ( 1 ), a known vinyl monomer, was synthesized using a phasetransfer catalyst, and homopolymerized with BF₃OEt₂ or EtAlCl₂.2-(9-Carbazolyl)ethyl 1-propenyl ether ( 2 ) was synthesized by transetherification of ethyl 1-propenyl ether with 9-(2-hydroxyethyl)carbazole in a yield of 34% as a mixture of 49% cis and 51% trans isomer. It was homopolymerized in 90% yield with EtAlCl₂ in toluene at ?25°C. Copolymerization of 1 or 2 with ethyl vinyl ether ( 3 ) were initiated with BF₃OEt₂ or EtAlCl₂. The yields of copolymers were 78–93%, depending on the polymerization conditions. The solubility of both homo- and copolymers was found to be poor. The glass transition temperatures of poly( 1 -co- 3 ) and poly( 2 -co- 3 ) are much lower, than those of poly( 1 ) and poly( 2 ).     

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.     

Synthesis of poly(vinyl ether)s with perfluoroalkyl pendant groups

2-Perfluoro(alkyl)ethyl vinyl ethers, F(CF₂)_nCH₂CH₂OCH?CH₂, (n = 6 or 8), were synthesized and polymerized by means of cationic initiators (HI/ZnI₂ and CF₃SO₃H/(CH₃)₂S). The perfluorohexyl-substituted poly(vinyl ether) is completely amorphous. The polymer with perfluorooctyl segments shows side chain crystallization with a disordering transition. For the corresponding perfluorooctyl monomer a liquid-crystalline phase was observed before melting. Copolymerization experiments of the flurocarbon-segmented monomers with a vinyl ether containing a cyanobiphenyl group in the side chain did not give homogeneous copolymers. This is attributed to the slower rate of polymerization of the fluorinated vinyl ethers as compared with the liquid-crystalline comonomer.     

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.     

Über copolymere der p-vinylbenzolboronsäure mit styrol

The reactivity ratios of the radical solution copolymerization for the systems p-vinylbenzeneboronic acid ( 1a ) (M₁)/styrene, resp. bis(trimethylsilyl) p-vinylbenzeneboronate ( 1b ) (M₁)/styrene were determined by means of boron analyses:

• 1a: r₁=0,28±0,06 and r₂=0,83±0,04
• 1b: r₁=0,28±0,10 and r₂=0,87±0,08

By cleavage of the trimethylsilyl groups, the 1b /styrene copolymers are smoothly transformed into 1a /styrene copolymers. The lithium, sodium, and potassium salts of some copolymers were prepared. The solution viscosities of the polymeric boronic acids in benzene/methanol mixtures and in dimethyl sulfoxide (DMSO) markedly depend on the boronic acid content. In benzene/methanol mixtures the preferential solvatation of the boronic acid groups by methanol can be ascertained. Further, the introduction of boronic acid groups in polystyr-enecorresponds with an increase of theglass transition temperature. The torsion pendulum measurements show that the pressure-molding of the polymers causes the formation of crosslinks, which are boronic acid anhydrides. These crosslinks can be cleaved by protic solvents.     

Derivatization of hydroxyl into α-chloro ether: application to the synthesis of block copolymers from hydroxy-telechelic polymers

It has been recently shown that a-halogeno ether, when activated by a weak Lewis acid such as ZnX₂, may be used as initiator for the living cationic polymerization of vinyl ethers. A route to the a-halogeno ether function is the action of dry hydrogen halide on an alcohol in the presence of an aldehyde or a cyclic acetal. The quantitative preparation of α-chloro ethers by this route, as well as the use of such compounds to initiate the “living” cationic polymerization of vinyl ethers, was examined. This procedure was then applied to hydroxy-telechelic polybutadiene to give a macro-initiator with α-chloro ether terminal groups. The latter was used to initiate the polymerization of vinyl ethers. The synthesis of poly(butadiene-block-ethyl vinyl ether) and poly(butadiene-block-2-chloroethyl vinyl ether) is reported, as well as the preparation of other copolymers by chemical modification of the chloroethyl vinyl ether units.     

Synthesis and Thermosensitive Properties of Poly[(N‐vinylamide)‐co‐(vinyl acetate)]s and Their Hydrogels

Free radical copolymerization of water‐soluble N‐vinylamides such as N‐vinylacetamide (NVA) and N‐vinylformamide (NVF) with hydrophobic vinyl acetate (VAc) gave amphiphilic copolymers. The monomer reactivity ratios were determined as r₁ = 5.8 and r₂ = 0.68 (M₁ = NVA, M₂ = VAc) and r₁ = 6.2 and r₂ = 0.37 (M₁ = NVF, M₂ = VAc), respectively. The growing radical of the terminals of N‐vinylamides propagates more favorably for N‐vinylamide monomers than for VAc monomer, resulting in the possible formation of blocky copolymers. It is found that aqueous solutions of these amphiphilic copolymers exhibited a lower critical solution temperature (LCST), depending on their chemical composition, followed by coacervate formation above the LCST. Furthermore, thermosensitive hydrogels could be prepared by the free radical copolymerization of N‐vinylamide and VAc in the presence of the crosslinker butylenebis(N‐vinylacetamide) (Bis‐NVA). The swelling ratios of these hydrogels decreased with an immediate increase in temperature from 20 to 80 °C, and then reversibly increased with decreasing temperature. These hydrogels showed the same thermosensitive properties as linear copolymers of NVF and VAc.

Relationship between LCST and vinyl acetate content in poly(N‐vinylamide‐co‐VAc)s.     

Living cationic polymerization of cyclohexyl vinyl ether

The cationic polymerization of cyclohexyl vinyl ether (CHVE) initiated by α-halogeno ethers in the presence of a Lewis acid activator has been investigated first. In conditions leading to a living polymerization of alkyl vinyl ethers (ethyl, isobutyl, etc.), an extremely fast polymerization, accompanied by chain transfer reactions, is observed with CHVE. In fact, we have shown that the polymerization of this monomer may be directly initiated by the HI and HCl adducts of CHVE, in the absence of any electrophilic activator. However, even in these conditions, the polymerization cannot be controlled. A “living” polymerization of CHVE was finally obtained by addition of ammonium salts (NBu₄X; X = Cl, Br, I) to the systems free of electrophilic activators. The added salts stabilize the α-halogeno ether chain ends and reduce the overall reactivity. Using this procedure, we have synthesized poly(CHVE)s with M?_n's ranging from 6 · 10³ to 4 · 10⁴ g · mol^?1 (in good agreement with the predicted values assuming the formation of one polymer chain per initiator molecule) and narrow molecular weight distributions (M?_w/M?_n < 1,2). Though most of poly(alkyl vinyl ether)s exhibit glass transition temperatures far below 0°C, the glass transition temperature of the poly(CHVE) is close to +50°C, indicating that this monomer can be used as a precursor to rigid poly(vinyl ether) blocks.     

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).     

Investigations on polyethers containing nitro-groups. I. The cationic copolymerization of glycidyl nitrate with other cyclic ethers

Cationic copolymerizations of glycidyl nitrate (GN) with some cyclic ethers were carried out to determine conditions under which glycidyl nitrate could be copolymerized with other ethers. Propylene oxide (PO), 3.3-bis(chloromethyl) oxacyclobutane (BCMO), THF and trioxane (TO) were used as comonomers. In LEWIS acids, boron trifluoride complexes were the most active catalysts. The copolymerization parameters were estimated as follows: r₁ = 0.03 and r₂ = 1.85 for GN(M₁)/PO(M₂), r₁ = 0.07 and r₂ = 0.88 for GN(M₁)/THF(M₂) and r₁ = 0.3 and r₂ = 0.35 for GN(M₁)/TO(M₂) copolymerization.     

Photo-oxydation des polyéther-bloc-polyamides, 2. Influence de la composition des polymères multiséquencés

Analytical and kinetical aspects of the photooxidation in the solid state of two polyether-block-polyamides 1c and 1d are described. The block copolymers studied contain different polyether sequences at different percentages. In copolymer 1d as well as in copolymers 1a and 1b , previously studied, the photooxidation concerns mainly the ether groups. High maximal concentrations of hydroperoxy groups, ? CH(OOH)? O? CH₂? , are observed (0,12 mol.kg^?1). These hydroperoxides are converted into hemi-acetals, ? CH(OH)? O? CH₂? , saturated esters and formate through photolysis or thermolysis above 60°C. The hemi-acetal groups are thermo-unstable too and decompose into alcohol and aldehyde groups. The photooxidation of copolymer 1c presents different features. At long wavelengths, low stationary concentration of hydroperoxy groups are observed (0,02 mol.kg^?1). Hydroperoxidation of the polyamide 6 sequences is revealed by the formation of imide groups. Hydroperoxidation of the poly(propylene glycol) sequences are surprisingly located on the ether methylene groups. Excitation of polyamide 6 sequences at short wavelength (254 nm) induces the formation of crotonized aldehyde groups.     

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.     

Cationic polymerization and copolymerization of vinylferrocene

Vinylferrocene was shown to undergo readily cationic polymerization by FRIEDEL-CRAFTS and other cationic catalysts. The polymers obtained possessed rather low molecular weights, the highest being 3500. In spite of the high reactivity of the ferrocene nucleus towards electrophilic substitution, no mode of propagation other than vinyl addition was detected when the infrared spectra of polymers prepared by cationic and free radical reactions were compared. The electronic spectra of polyvinylferrocene and its oxidized form were similar to those of ferrocene and ferricinium ion, respectively. In the cationie copolymerization with styrene, the latter was incorporated into the polymer only when the styrene content in the monomer feed exceeded 90%. The copolymerization with vinyl isobutyl ether (M₂) by BF₃OEt₂ in toluene at 0°C gave the reactivity ratios: r₁ = 0.1 ± 0.1, r₂ = 9.7 ± 1.0. The high cationic reactivity of vinylferrocene is consistent with the stability of the α-ferrocenylearbonium ion inferred from solvolysis and other reactions.     

Methine and α-methyl proton resonance in methyl acrylate/methacrylonitrile copolymers

Methyl acrylate (A)/methacrylonitrile (M) copolymers, prepared by emulsion and solution polymerization at 50°C, were characterized by 220 MHz NMR spectroscopy. The methine and α-methyl proton resonances of such copolymers consisted of three peak patterns, individual resonance areas being assignable to protons centered in various A or M centered triads. Triad fractions determined from methine and α-methyl resonance patterns were in excellent agreement with calculated values based on reactivity ratios of r_A = 0.39 ± 0.06 and r_M = 3.56 ± 0.50 for copolymers prepared in emulsion and on reactivity ratios of r_A = 0.24 ± 0.02 and r_M = 3.21 ± 0.11 for copolymers prepared in solution.