Branched Polymers Through Redox Emulsion Polymerization Using Peroxide Monomer As The Branching Agent

Redox emulsion polymerization to branched vinyl polymers in the presence of 2-(tert-butylperoxy)ethyl methacrylate (BPEMA), ferrous sulfate, and sodium formaldehyde sulfoxylate (SFS) is reported in this paper. The peroxide monomer BPEMA containing alkyl peroxide was designed for high stability during preparation and storage. Nuclear magnetic resonance spectroscopy (NMR), Raman, and triple-detection size-exclusion chromatography (TD-SEC) measurements were used to reveal the polymerization procedure and provide evidence of branching structure. In the case of polymerization at St(100)-BPEMA(1.0)-FeSO4 0.5-SFS0.2, the molecular weight increased and decreased with conversion below and above 75% monomer conversion, respectively. The decreasing of molecular weight with monomer conversion came from the increased viscosity of the micelle, which makes it difficult for the formed macromolecules containing vinyl group to participate into polymerization. Finally, the molecular weight reached a value of M-n. SEC = 439,200 g/mol at 92.2% conversion. In addition, the Zimm branching factor, g', also decreased and increased with conversion below and above 60% conversion, respectively, and then the g' finally attends a value of 0.41, showing high degree of branching. Branched poly(methyl methacrylate) was also prepared through this strategy, showing a versatile approach to branched vinyl polymers.