Copolymerization of styrene. IV. Copolymerization with esters of benzylidenecyanoacetic acid

Abstract

synopsisStyrene was copolymerized in bulk with a number of esters of benzylidenecyanoacetic acid. The kinetic scheme of all pairs fitted the improved scheme of copolymerization, taking into account the effect of the penultimate unit. The Alfrey-Price Q and e values were calculated. Using the modified Taft equation, log ( l h ) = p*u* + SE,, it was found that the relative reactivities of the ester monomers toward the polystyryl radical were correlated by the polar substituent constants u* of the ester alkyl groups ( p * = 0.14) and not by their steric substituent constants E, (6 = 0.008). RbumQLe styrene a 6t6 copolymBris6 en masse avec certains esters de l'acide benzylidbnecyanoac6tique. Le schema cin6tique de toutes les paires est conforme au schema de copolym6risation am6lior6 qui tient compte de l'effet de l'unit6 p6nultihme. Les valeurs Q et e selon Alfrey-Price ont 6t6 calcul6es. Utilisant 1'6quation de Taft modifibe, log ( l h ) = p*u* + SE,, il a 6th trouv6 que les r6activit6s relatives des comonombres B l'bgard de l'attaque du radical polystyryle sont influencbs par les constantes des substituants polaires u* ( p * = 0.14) mais non pas par les constantes des substituants st6riques E,,(S = 0.008) des substituants alcoyl6s des esters. ZusammenfassungStyrol wurde in Substanz mit mehreren Ester der Beneylidencyanessigsaure copolymerisiert. Alle Paare entsprachen dem verbessertem Reaktionsschema der Copolymerisation, das den Einfluss der Vorletzten Gruppe berucksichtigt. Die Alfrey-Price Q und e Werte wurden berechnet. Bei Benutzung der modifizierten Taft Gleichung, log (l/rl) = p*u* + SE., wurde gefunden, dass die relativen Reaktivitaten der EsterMonomere gegen Polystyrolradikale von den polaren Substituentenkonstanten u* ( p * = 0.14), nicht aber von den sterischen Substituentenkonstanten E, (6 = 0.008) der Alkylgruppen der Ester abhiingen.

N‐Oxyl‐Controlled Radical Copolymerization of Styrene with Ethyl α‐Cyanocinnamate

“…We found reactivity ratios of r 1 ¼ 0.47 and r 2 ¼ 0 for the N-oxyl-controlled radical copolymerization from styrene and ethyl a-cyanocinnamate. This stands in good agreement to the values described by Kohn et al [1] of r 1 ¼ 0.51 and r 2 ¼ 0 for the radical polymerization. Figure 7 shows the experimental values of the copolymer composition in the copolymer block in dependence on the ethyl a-cyanocinnamate in the reaction solution.…”

“…It lies near 30 mol-% ethyl-acyanocinnamate. The maximum of the polymerization rate agrees very well with the data known in literature from Kohn et al [1] It can be attributed to styrene as an electron donator and ethyl a-cyanocinnamate as electron acceptor ( Figure 5). …”

“…An increase of the glass transition temperature of polystyrene can be determined for the block copolymers with higher concentrations of ethyl a-cyanocinnamate. But in fact, the resulting glass transition temperature of the synthesized copolymers are much lower than of the copolymers synthesized by Kohn et al [1] They found a glass transition temperature of about 200 8C for a copolymer synthesized by radical copolymerization with the same over all composition of 40 mol-% ethyl a-cyanocinnamate. This can be explained with the difference in the molar masses of the copolymers in comparison with those from the radical polymerization by Kohn et al Polymers with a higher polymerization degree have higher glass transition temperatures in contrast to those polymers with a lower polymerization degree.…”

“…The radical copolymerization of ethyl a-cyanocinnamate was intensively examined at the beginning of 1960 by Kohn et al [1][2][3][4] They carried out experiments investigating the copolymerization behavior of ethyl a-cyanocinnamate with styrene, 2-acrylonitrile, 3-vinylacetate and different acrylesters (methyl, ethyl and butyl acrylate) with up to 10% conversion. Homopolymerization products of ethyl a-cyanocinnamate could not be found.…”

“…Kohn et al [1] also examined the influence of the ester group of ethyl a-cyanocinnamate on the copolymerization behavior with styrene. For this purpose they synthesized the methyl, ethyl, butyl, hexyl, cyclohexyl, benzyl and 2-ethyl hexylesters of a-cyanocinnamic acid and carried out copolymerizations with styrene in bulk at 70 8C and partly at 80 8C in presence of dibenzoyl peroxide (BPO).…”