Cinétiques de télomérisation, 1. Determination des lois applicables à la synthèse des télomères à DP_n moyens en télomérisation radicalaire

Abstract

The kinetics of free radical telomerization was studied. The theoretical relations that can be applied in reactions of this type, were evaluated. When transfer predominates, the equations giving the variations of monomer, telogen and initiator as a function of time were established. Moreover, instantaneous and cumulated number and weight average degrees of polymerization were calculated. The resulting relations were checked on the example of the telomerization of 2,3-epoxypropyl methacrylate with bromotrichloromethane in the presence of two initiators and two different temperatures. Comparison of the experimental results with the theoretical ones revealed the scope of application of the general formulae giving the average degrees of polymerization.La ttlomtrisation radicalaire d'un monomere M avec un ttlogkne XY amorcte par I, s'tcrit gtneralement de la faGon suivante: Amorcage: Propagation: Transfert: Terminaison: kd ko 12 -

Synthesis of poly(vinylidene fluoride)‐b‐poly(styrene sulfonate) block copolymers by controlled radical polymerizations

“…The decrease of molar mass versus conversion is characteristic of a conventional radical telomerization reaction 33, 43. As previously demonstrated,44, 45 the evolution of the number‐average molar mass with monomer conversion, in the case of telomerization reaction, can be predicted by the following equation: where [M] 0 , M monomer [CTA] 0 , p , and C Tr stand for the initial monomer concentration, the molar mass of the monomer, the initial CTA concentration, the conversion, and the transfer constant of the CTA ( C Tr = k Tr / k p ), respectively.…”

“…The decrease of molar mass versus conversion is characteristic of a conventional radical telomerization reaction. 33,43 As previously demonstrated, 44,45 the evolution of the numberaverage molar mass with monomer conversion, in the case of telomerization reaction, can be predicted by the following equation:…”

Synthesis of semitelechelic poly[N-(2-hydroxypropyl)methacryl-amide] by radical polymerization in the presence of alkyl mercaptans

“…The polymerization is initiated either by radicals formed by the decomposition of the initiator 23) or by mercaptan radicals after a radical transfer reaction between a primary radical and a mercaptan 9,24) . The data shown here demonstrated that the formation of non-functional PHPMA-IBN chains depended on both the concentration of initiator and mercaptan, and suggested that there might be a competition of the two initiation mechanisms, depending on the reaction conditions (Scheme 1).…”

“…The relative amount of non-functional polymer chains (PHPMA-IBN) varied, as expected, with the molar ratios of mercaptan and AIBN to HPMA 22) . It is well known that different radicals may participate in the initiation reaction of the radical polymerization in the presence of mercaptans 9,[22][23][24] . It appears that to synthesize ST polymers with a high degree of functional- ity, a better understanding of the polymerization in the presence of mercaptans is needed.…”

Dependence of transfer reaction on solvent in the free radical polymerization of styrene: application to the synthesis of PS/PEO copolymers using PEO-based transfer agents

“…Because the SEC columns were calibrated with PS standards, a difference was found between the numberaverage molar masses obtained by NMR and SEC. The cumulative number-average molar masses (M n, th ) were calculated using the following equation: [15] DP n cum a R 0 1 À 1 À aC t 2…”