Synthesis of Silicone-Acrylic Emulsions by ARGET ATRP Polymerization and Its Polymerization Kinetics

Methyl methacrylate (MMA), ethyl acrylate (EA), butyl acrylate (BA) and isooctyl acrylate (2-EHA) were used as the main monomers; γ-methacryloxypropyl trimethoxysilane (KH-570) was used as the silicone functional monomer; a reactive emulsifier and sodium dodecyl sulfate were used as the composite emulsification system; ethyl 2-bro-moisobutyrate (EBIB) was used as the initiator; and copper bromide was used as the catalyst. A silicone-acrylic emulsion was prepared by the activators regenerated by electron transfer-atom transfer radical polymerization (ARGET-ATRP) with 2-bipyridine as the ligand and ascorbic acid as the reducing agent. The effects of temperature, initiator, organosilicon and bipyridine on the reaction kinetics were studied, and the polymers were characterized by infrared spectroscopy, gel permeation chromatography (GPC) and nuclear magnetic resonance spectroscopy. When the temperature increased, the conersion and the polymerization rate increased, and the apparent activation energy Ea was 79.65 kJ·mol^-1. A greater initiator amount correlated to a higher conversion, a higher polymerization rate and a lower molecular weight. An increase in the amount of silicone increased the conversion and the reaction rate to 0.5% and 1%, respectively. With increasing silicone content, the gel content of the polymer, the molecular weight and PDI increased; when the silicone content was 4%, the polymer could not be dissolved by tetrahydrofuran. The characterization showed that MMA, EA, BA, 2-EHA, KH-570 and the reactive emulsifier SR-10 were all involved in the polymerization. ARGET-ATRP had a controllable molecular weight and narrow molecular weight distribution. Due to the addition amount and cost, few industrial applications exist. Therefore, in this study, the application of ARGET-ATRP on wood paint and the control of the molecular weight of the polymer to meet large-scale industrial application needs were examined.