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Use of a Novel Tetrafunctional Initiator in the Free Radical Homo‐ and Copolymerization of Styrene, Methyl Methacylate and α‐Methyl Styrene

An investigation into the effect of initiator functionality on the free radical polymerization of various monomer systems including styrene, methyl methacrylate (MMA), styrene–MMA and α‐methyl styrene–MMA with a tetrafunctional peroxide initiator (JWEB50) was completed. The performance of the tetrafunctional initiator was compared to a monofunctional counterpart (TBEC). Kinetic results showed that regardless of the monomer system studied, JWEB50 produced a faster rate of polymerization compared to TBEC at an equivalent concentration. Molecular weights, radii of gyration and intrinsic viscosities were obtained from two size exclusion chromatography setups: one equipped with a multi‐angle laser light scattering detector and the other with low‐angle laser light scattering and viscosity detectors. For the homopolymerization of styrene, JWEB50 produced polymer molecular weights similar to TBEC at the same concentration, while experiments with MMA indicated that JWEB50 produced molecular weights closer to those obtained with TBEC at a concentration four times as great. Runs with a feed mixture of styrene and MMA gave results that were a combination of the observations made for the individual homopolymerizations. The results for the feed mixture of MMA and α‐methyl styrene were similar to the findings with pure styrene. Plots of radius of gyration, intrinsic viscosity and their corresponding branching factors provided evidence of branching for all cases except for the homopolymerization of MMA.