Copolymerization of Styrene and α-Methylstyrene in the Presence of a Catalytic Chain Transfer Agent

Abstract

Copolymerizations of styrene (STY) and α-methylstyrene (AMS) have been performed at different monomer feed compositions and temperatures (40−70 °C) in the presence of the catalytic chain transfer agent bis(boron difluorodimethylglyoximate)cobaltate(II) (COBF). The average chain transfer constant, 〈C S〉, was found to increase approximately 3 orders of magnitude upon going from pure STY to pure AMS. The addition of only 10% AMS increased the 〈C S〉 by 1 order of magnitude. This behavior can be predicted from the relative fractions of growing radical end groups, which results in the majority of polymer chains being formed with an unsaturated AMS end group. No significant penultimate unit effects in the chain transfer reaction were observed. The addition of 10−20% AMS results in the majority of the growing radicals having AMS end groups, and hence AMS dominates the catalytic chain transfer reaction. The 〈C S〉 values continue to increase as the AMS content is increased beyond 20%; however, this can be mostly attributed to a decrease in 〈k p〉 rather than an increase in 〈k tr〉. The expected end groups in the homopolymerization of AMS in the presence of COBF were confirmed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS).

Preparation and characterization of oligomeric terpolymers of styrene, methyl methacrylate and 2-hydroxyethyl methacrylate: A comparison of conventional and catalytic chain transfer

“…Previous studies of catalytic chain transfer copolymerization have indicated that conventional copolymerization propagation kinetics are applicable to catalytic chain transfer polymerization. [14,16] In summary, the results validate the long chain assumption and are consonant with conventional copolymerization kinetics.…”

“…5 adequately reproduces the experimental results. Combining this theoretical approach with previously reported models [14,16] used to predict chain transfer kinetics in copolymerization extends the theoretical framework to multi-component polymerizations in the presence of chain transfer agents.…”

“…The glass transition temperature of the polymer and the thermal degradation behaviour is dependent on the oligomer endgroups. Previous work [14,16] on utilising CCT to control end-group chemistry could be combined with this work to target thermally stable oligomers. Fig.…”

Copolymerization of methyl methacrylate and butyl acrylate in the presence of a chain transfer agent

“…[9] The same group has also studied the C T in the copolymerization of S with a-methylstyrene to a CCTA. [10] In both cases, the C T vary with the monomer feed composition and their values are in good agreement with model predictions based upon both terminal and penultimate unit models of free-radical copolymerization. [9,10] In a recent publication, [11] the average chain-transfer constant in the copolymerization of methyl methacrylate and butyl acrylate to dodecanethiol (DDT) was determined for only two different monomer feed compositions.…”

“…[9,[11][12][13][17][18][19][20] The chain length distribution method (CLD) uses the number molecular weight distribution. [9][10][11][12][13] For a polymerization completely governed by chain transfer, the molecular weight distribution can be expressed as the following exponential: [16] PM…”