Novel cyano-containing copolymers of vinyl esters for piezoelectric materials

The synthesis of a series of novel cyano-containing copolymers is described. Alternating copolymers of acrylonitrile with vinyl esters are obtained by increasing the electrophilic character of the nitrile monomers by complexation with zinc chloride. Copolymers of methyl and ethyl α-cyanoacrylates with vinyl esters are prepared using radical initiators in the presence of 7% acetic acid as inhibitor for anionic polymerization. The copolymers of methyl α-cyanoacrylate with the vinyl esters have T_g's above 140°C. Methyl vinylidene cyanide (MVCN) copolymerizes spontaneously with para-substituted styrenes to yield copolymers with high inherent viscosities and high T_g (160°C) and the copolymer of MVCN with vinyl acetate is also synthesized. The pyroelectric constants p for these polymers were measured and the values of p for the copolymers of vinyl acetate with methyl β,β-dicyanoacrylate, methyl α-cyanoacrylate, or MVCN were in the same range as the well-studied vinylidene cyanide/vinyl acetate copolymer. A higher concentration of dipoles generally results in higher T_g's and higher pyroelectric coefficients. © 1992 John Wiley & Sons, Inc.     

Free-radical polymerization of vinyl ferrocene

The results of quantitative studies of the rates of free-radical polymerization of vinyl ferrocene indicate that the latter has polymerization characteristics similar to those of styrene. The rates of homopolymerization of these two monomers in benzene at 70°C. were measured with the use of azobisisobutyronitrile as catalyst. The rate constants (k = R_p/[M][I]^1/2) are k_VF = (1.1 ? 1.8) × 10^?4, k_STY = 1.65 × 10^?4. Small amounts of vinyl ferrocene and styrene have similar effects on the rates of polymerizations of methyl methacrylate and ethyl acrylate and on the molecular weights of the resulting polymer. Polystyrene and poly(vinyl ferrocene) with similar molecular weights are isolated from polymerizations carried out under identical conditions. The rates of copolymerization of vinyl ferrocene—methyl methacrylate, vinyl ferrocene—styrene, and styrene—methyl methacrylate were determined by following the disappearance of monomers by means of gas chromatographic analyses. The relative reactivity for vinyl ferrocene is slightly lower than that for styrene.     

Chain transfer constants for vinyl monomers polymerized in methyl oleate and methyl stearate

Chain transfer constants were obtained for styrene, methyl methacrylate, methyl acrylate and vinyl acetate, polymerized in methyl oleate and methyl stearate at 60°C. Transfer constants increased in the order: methyl methacrylate < styrene < methyl acrylate ? vinyl acetate in both solvents. Average values of the transfer parameters were: for methyl oleate, Q_tr = 2.04 × 10^?4, e_tr = 1.08; for methyl stearate, Q_tr = 0.373 × 10^?4, e_tr = 1.01. Indication that polar species predominate in the transition state is supported by the observed order of reactivity. The usual rate dependence appeared to be followed by all of the monomers except vinyl acetate, which was retarded, severely in methyl oleate. Transfer in methyl oleate was about 5.8 times greater than that found in methyl stearate for these four monomers. The internal allylic double bond of methyl oleate had about the same reactivity in transfer as had the terminal unsaturation in N-allylstearamide at 90°C. Rough estimates were obtained of the monomer transfer constants for the long side-chain homologs of these four monomers from the respective monomer transfer constants and the experimental transfer constants, corrected for transfer to the labile groups of the solvent. It was concluded that the rate of polymerization would determine in large measure the degree of polymerization for the reactive 18-carbon homologs but that the molecular weight of poly(vinyl stearate) and (oleate) will be regulated primarily by transfer to monomer.     

Michael additions to acrylonitrile,methyl acrylate and methyl vinyl ketone to Nb-benzylidenetryptophan methyl ester

Michael addition to methyl acrylate and methyl vinyl ketone of N_b-benzylidene-L-tryptophan methyl ester 1 gave 2-(3-indolylmethyl)glutamic dimethyl ester 2a and α-(3-oxobutyl)tryptophan methyl ester 2b respectively. Addition to acrylonitrile of 1 yielded α,N_a-dicyanoethyltryptophan methyl ester 3 .     

Stereoregularity of poly(vinyl ether)

α-Methylvinyl isobutyl and methyl ethers were polymerized cationically and the structure of the polymers was studied by NMR. Poly(α-methylvinyl methyl ether) polymerized with iodine or ferric chloride as catalyst was found to be almost atactic, whereas poly(α-methylvinyl isobutyl ether) polymerized in toluene with BF₃OEt₂ or AlEt₂Cl as catalyst was found to be isotactic. In both cases, the addition of polar solvent resulted in the increase of syndiotactic structure as is the case with polymerization of alkyl vinyl ether. tert-Butyl vinyl ether was polymerized, and the polymer was converted into poly(vinyl acetate), the structure of which was studied by NMR. A nearly linear relationship between the optical density ratio D₇₂₂/D₇₃₆ in poly(tert-butyl vinyl ether) and the isotacticity of the converted poly(vinyl acetate) was observed.     

Diels-Alder Regioselectivity Controlled by Remote Substituents. The Cycloadditions of 1-(Dimethoxymethyl)-2,3-dimethylidene- and -2,3,5,6-tetramethylidene-7-oxabicyclo[2.2.1]heptanes

The syntheses of 2,3-dimethylidene- and 2,3,5,6-tetramethylidene-7-oxabicyclo[2.2.1]heptanes substituted in position C(1) are reported. The 1-dimethoxymethyl group in derivatives 2 and 6 controls the regioselectivity of the Lewis-acid-catalyzed Diels-Alder additions with methyl vinyl ketone and butynone. For the EtAlCl₂-catalyzed addition of methyl vinyl ketone to 6 , the regioselectivity can be reversed by a small solvent modification. The tetraene 2 is a versatile reagent for regioselective ‘tandem’ cycloadditions.     

Reaction of Organylchlorosilanes with Dimethyl Sulfoxide in the Presence of Octamethyltrisiloxane

Dichloro(methyl)(vinyl)silane reacts with DMSO in the presence of octamethyltrisiloxane to form cyclooligomethyl(vinyl)siloxanes(MeViSiO) _n (n = 3-6). The reaction involves disproportionation of octamethyltrisiloxane into hexamethyldisiloxane and decamethyltetrasiloxane. Along with the latter two products, insertion products of methyl vinyl silanone into both permethyloligosiloxanes were identified. Alkyltrichlorosilanes RSiCl₃ (R = Me, Et) react with DMSO in the presence of octamethyltrisiloxane to form cyclic oligoalkyltrichlorosiloxanes (RClSiO) _m (m = 3-6).     

Copolymerization of allyl esters of some fatty acids

Attempts have been made unsuccessfully to homopolymerize a number of allyl esters of substituted fatty acids by radical initiation in emulsion systems. Copolymerizations of these allyl esters with styrene, methyl methacrylate, and vinyl chloride have been investigated. Of these comonomers, styrene and methyl methacrylate do not copolymerize well with the allyl esters, whereas vinyl chloride does. Reactivity ratios for the radical copolymerization of allyl 11-iodoundecanoate, M₁, and vinyl chloride, M₂, determined at 60°C. in benzene, are r₁ = 0.42 and r₂ = 1.64. A copolymer of allyl 10, 11-dibromoundecanoate and vinyl chloride was fractionated and found to be fairly homogeneous.     

Neodymium Catalyst for the Polymerization of Dienes and Polar Vinyl Monomers

Ziegler–Natta catalysts have played a major role in industry for the polymerization of dienes and vinyl monomers. However, due to the deactivation of the catalyst, this system fails to polymerize polar vinyl monomers such as vinyl acetate, methyl methacrylate, and methyl acrylate. Herein, a catalytic system composed of NdCl₃⋅3TEP/TIBA is reported, which promotes a quasi‐living polymerization of dienes and is also active for the homopolymerization of polar vinyl monomers. Additionally, this catalytic system generates polymyrcene‐b‐polyisoprene and poly(myrcene)‐b‐poly(methyl methacrylate) diblock copolymers by sequential monomer addition. To encourage the replacement of petroleum‐based polymers by environmentally benign biobased polymers, polymerization of β‐myrcene is demonstrated with a catalytic activity of ≈106 kg polymer mol Nd⁻¹ h⁻¹.     

Iron powder and tin/tin chloride as new reducing agents of Meerwein arylation reaction with unexpected recycling to anilines

Abstract

Simple and rapid route for Meerwein arylation reaction using iron powder or a mixture of tin/tin chloride has been developed. In the presence of iron powder, different aryl diazonium salts reacted with methyl vinyl ketone, acrylates, and isopropenyl acetate. Production of oximes was detected as the main product with acrylates or in a mixture with β-aryl methyl ketones in the case of methyl vinyl ketone. The in situ produced HNO₂ from an excess of NaNO₂/HCl was trapped by alkyl aryl radical to form oximes in the E configuration form. The presence of tin/tin chloride mixture in the reaction of the aryl diazonium salts with methyl vinyl ketone produced Michael products along with β-aryl methyl ketones. The predicted α-aryl methyl ketones from the reaction of isopropenyl acetate with the diazotized anilines were obtained using iron or tin/tin chloride mixture.     

Syntheses and radical polymerizations of novel optically active vinyl and isopropenyl carbamates having L-leucine structures

Syntheses and radical polymerizations of vinyl and isopropenyl carbamates having L -leucine methyl ester structures, N-vinyloxycarbonyl-L -leucine methyl ester (VOC-L-M) and N-isopropenyloxycarbonyl-L -leucine methyl ester (IOC-L-M), were carried out. VOC-L-M and IOC-L-M were prepared by the reactions of L -leucine methyl ester with vinyl and isopropenyl chloroformates in the presence of sodium hydrogen carbonate. The radical polymerization of VOC-L-M with AIBN (1 mol %) in bulk, chlorobenzene, methanol, and N,N-dimethylformamide afforded the corresponding polymer (poly(VOC-L-M)) with M _n 7,400–19,000. Meanwhile, IOC-L-M afforded no polymer with AIBN at 60°C but afforded a polymer having low molecular weight with BPO at 80°C. The glass transition temperatures of poly(VOC-L-M) and poly(IOC-L-M) were 53 and 65°C, respectively. The 10% weight loss temperatures of poly(VOC-L-M) and poly(IOC-L-M) under nitrogen were 255 and 173, respectively. The copolymerization parameters of VOC-L-M (M₁) and vinyl acetate (M₂) were evaluated as r₁ = 0.92 and r₂ = 0.63. © 1996 John Wiley & Sons, Inc.     

Determination of the reactivity ratios of methyl acrylate with the vinyl acetate,vinyl 2,2-dimethyl-propanoate,and vinyl 2-ethylhexanoate

The course of composition drift in copolymerization reactions is determined by reactivity ratios of the contributing monomers. Since polymer properties are directly correlated with the resulting chemical composition distribution, reactivity ratios are of paramount importance. Furthermore, obtaining correct reactivity ratios is a prerequisite for good model predictions. For vinyl acetate (VAc), vinyl 2,2-dimethyl-propanoate also known as vinyl pivalate (VPV), and vinyl 2-ethylhexanoate (V2EH), the reactivity ratios with methyl acrylate (MA) have been determined by means of low conversion bulk polymerization. The mol fraction of MA in the resulting copolymer was determined by ¹H-NMR. Nonlinear optimization on the thus-obtained monomer feed–copolymer composition data resulted in the following sets of reactivity ratios: r_MA = 6.9 ± 1.4 and r_VAc = 0.013 ± 0.02; r_MA = 5.5 ± 1.2 and r_VPV = 0.017 ± 0.035; r_MA = 6.9 ± 2.7 and r_V2EH = 0.093 ± 0.23. As a result of the similar and overlapping reactivity data of the three methyl acrylate–vinyl ester monomer systems, for practical puposes these data can be described with one set of reactivity data. Nonlinear optimization of all monomer feed–copolymer composition data together resulted in r_MA = 6.1 ± 0.6 and r_VEst = 0.0087 ± 0.023. © 1994 John Wiley & Sons, Inc.     

Thermal rearrangements of polybutadienes with different vinyl contents

A study was made of the loss of double bonds in equibinary (1,4-1,2) polybutadiene (EB) and in polybutadienes with 30% 1,2, 70% 1,4 (FI), and 10% 1,2, 90% 1,4 (DI) double-bond content, when heated in vacuum under nonpyrolytic conditions (temperature range 220–280°C). These polymers were found to undergo second-order loss of 1,2 unsaturation with similar activation energies (E_a = 34.0 ± 3 kcal/mole), by analogy to the previously reported thermally induced loss of double bonds in 1,2-polybutadiene (VB) (E_a = 33.6 ± 3 kcal/mole). Moreover, EB and FI exhibited also second-order loss of 1,4 unsaturation, with E_a ca. 36 and 40 kcal/mole, respectively, while DI showed negligible loss of 1,4 unsaturation below 260°C, in common with cis-1,4-polybutadiene (CB) (with 2% 1,2 double bonds) examined earlier. The loss of 1,2 double bonds in the various polybutadienes with different vinyl contents is accompanied by substantial methyl production, ranging from about one methyl group formed for every 4–5 vinyl units lost in VB, to one methyl for every two vinyls lost in EB, and to almost one methyl for each vinyl lost in DI or CB. Mechanisms are proposed for the thermally induced loss of 1,2 and 1,4 unsaturation in various polybutadienes and for the accompanying methyl production.     

Organocuprates as Initiators for Methyl Methacrylate Polymerization

Abstract

Polymerizations of methyl methacrylate initiated by organocuprates in tetrahydrofuran solution have been investigated. The heterocuprate lithium n-butylcyanocuprate was found to be an effective initiator at - 78°C, and lithium di-n-butylcuprate was confirmed as an effective initiator; both species give rapid polymerization to virtually complete conversion of monomer. Polydispersities (M_w/M_n ) are about 1.5. Polymerizations have an inherent termination reaction and a low initiator efficiency. Polymerization of methyl vinyl ketone is virtually uncontrollable, and polymerizations of methyl methacrylate are inhibited by styrene.     

Graft polymers: Chain transfer and branching

The vinyl monomers, methyl methacrylate, ethyl methacrylate, and methyl acrylate were polymerized in the presence of chlorinated rubber or poly(vinyl chloride) in homogeneous solution with benzoyl peroxide as catalyst. A graft polymer was formed by a chain-transfer reaction involving the growing polymer radicals to the backbone of chlorinated rubber or poly(vinyl chloride), in addition to homopolymer from the monomer. The homopolymer was isolated from the polymer mixture by fractional precipitation from methyl ethyl ketone solution with methanol as precipitant. The chain-transfer constants for the branching reactions were evaluated. The ratios k_p/(k_t)^1/2 for the grafting reactions were obtained by a correlation of chain-transfer constants with the extent of branching. The chain-transfer data were correlated on the basis of an extension of the Q–e scheme of Alfrey and Price to polymer–polymer transfer reactions. Specific effects due to the backbone are found to have considerable influence on the course of the chaintransfer reactions and k_p/(k_t)^1/2 of the grafting reactions.     

Retardation of radical polymerization by phenylacetylene and its p-substituted derivatives

Radical polymerizations of styrene and methyl methacrylate in the presence of phenylacetylene and five of its p-substituted derivatives were carried out with the use of 2,2′-azobisisobutyronitrile as the initiator at 60°C. The initial overall rates of the polymerizations of styrene and methyl methacrylate in the presence of phenylacetylene were not proportional to the square root of the initiator concentration under the experimental conditions employed. The relationship between the overall polymerization rate and the concentration of the phenylacetylenes could be expressed by the Kice equation for the rate of a radical polymerization in the presence of a terminator. From this relationship the rate constant (k_s) of the reaction of a growing polymer radical with the phenylacetylenes and the constant C_s = (k_s/k_p), where k_p is the propagation rate constant of vinyl monomers, were determined. The C_s value thus obtained agree well with that derived from the relationship between the number-average degree of polymerization and the molar ratio of the phenylacetylenes to the vinyl monomer. Therefore the mechanism of the reaction may be considered as being one in which the growing radical reacts with the ethynyl group of the phenylacetylenes to yield a comparatively stable radical which terminates mainly by reaction with the growing radical, and so apparently the phenylacetylenes retard the vinyl polymerization. The substituent effects on the reaction were discussed on the basis of the following modified Hammett equation proposed by Yamamoto and Otsu: log [C_s(p-sub. PA)/C_s(PA)] = ρσ + γE_R where PA represents phenylacetylene, σ and E_R are the Hammett polar substituent constant and resonance substituent constant, respectively, and both ρ and γ are reaction constants. The γ value for the polymerization of both styrene and methyl methacrylate was 1.7. The ρ value was 1.0 for the polymerization of styrene and approximately zero for that of methyl methacrylate. These results demonstrate that the reactivity of the phenylacetylenes with the growing chain is influenced by both polar and resonance effects of their p-substituents in the degradative copolymerization of styrene and only by the resonance effect in that of methyl methacrylate.     

Copolymerization of propylene and methyl vinyl ketone with metallocene catalysts: Synthesis,properties, and thermal and photooxidation of modified polypropylene

The copolymers of propylene and methyl vinyl ketone are synthesized at 60°С by copolymerization in the propylene bulk in the presence of the polymethylaluminoxane-activated metallocene catalysts, namely, the isospecific С₂-symmetric metallocene catalyst rac-Me₂Si(2-Me-4-PhInd)₂ZrCl₂ and the syndiospecific Сs-symmetric metallocene catalyst Ph₂ССpFluZrCl₂, and characterized. It is shown that a noticeable insertion of methyl vinyl ketone into a polypropylene chain is possible during copolymerization initiated by the syndiospecific catalytic system, whereas in the case of the isospecific system, the insertion of methyl vinyl ketone is hindered. The thermal oxidation of the resulting polymers is studied. With the use of chemiluminescence, the accumulation of peroxy macroradicals under the action of daylight in samples based on isotactic and syndiotactic polypropylene is detected. It is found that even a low (0.2 mol %) content of methyl vinyl ketone endows polypropylene with the capability to undergo rapid and controlled degradation under natural conditions.     

Vinyl polymerization. 178. Copolymerizations of p-substituted phenyl vinyl sulfides

The copolymerizations of p-substituted phenyl vinyl sulfides (M₂) having OCH₃, CH₃, H, Cl, and Br substituents with styrene and methyl methacrylate (M₁) and their intercopolymerizations at 60°C. were studied. From the results of copolymerizations with styrene and methyl methacrylate, the monomer reactivity ratios and the Q₂e₂ values were determined. For example, the Q and e values for unsubstituted phenyl vinyl sulfide were 0.45 and ?1.26 in the copolymerization with methyl methacrylate. This result indicated the importance of the 3d orbital resonance between the sulfur atom and the adjacent carbon atom in the transition state of copolymerizations. The relative reactivities of these monomers toward the polymer radicals were found to be correlated with the Hammett σ constants of the substituents. In the intercopolymerizations of these monomers, it was also found that the relative reactivities followed the Hammett equation approximately.     

Application of vegetable oils for electrocatalytic synthesis of hydrocarbons

Conditions of Kolbe cross-electrosynthesis of 10-undecylenic and acetic acids are studied on different catalyst anodes. It is shown that the key anodic process stages are the stages of formation of vinyl radicals from anions of unsaturated and methyl radicals under electrosynthesis of acetate anions. As dependent on the conditions of the process, the main product formed on the anode of the Pt-10% Ir alloy is either hydrocarbon CH₃CH₂CH(CH₃)(CH₂)7CH₂CH₃ (58 wt %) being the product of addition of three methyl radicals to a vinyl radicals or olefin CH₂=CH(CH₂)₇CH₂CH₃ (57 wt %) being the product of dimerization of vinyl and methyl radicals.     

Synthesis and reactivity ratios of regioisomeric vinyl‐1,2,3‐triazoles with styrene

The free radical reactivity ratios between styrene and different vinyl‐1,2,3‐triazole regioisomeric monomers in 1,4‐dioxane at 65 °C have been established using nonlinear least square method. The results obtained for the reactivity ratio between regioisomers show exceptionally different polymerization behavior, highlighting the effects of the electronic and steric factors of these regioisomeric monomers. The experimental results highlight the effects of the electronic and sterics on the copolymerization behavior. In case of 1,4‐vinyl‐triazoles, it was found that without the steric effects, the reactivity is very similar to that of styrene and forms random copolymers. However, it was found that 1,5‐vinyl‐triazoles are more reactive than 1,4‐vinyl triazoles. In the case of styrene‐co‐1,4‐vinyl‐1,2,3‐triazoles, the reactivity ratios were calculated to be r_styrene: r_{1‐octyl‐4‐vinyl‐triazole} = 1.97:0.54, r_styrene : r_{1‐benzyl‐4‐vinyl‐triazole} = 1.62:0.50, and r_styrene: r_{1‐methyl‐4‐vinyl‐triazole} = 0.90:0.87. On the other hand, reactivity ratios for styrene‐co‐1,5‐vinyl‐1,2,3‐triazoles were found to be r_styrene: r_{1‐octyl‐5‐vinyl‐triazole} = 0.13:0.66 and r_styrene: r_{1‐benzyl‐5‐vinyl‐triazole} = 0.34:0.49. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 3359–3364