Preparation of Copoly(styrene/butyl methacrylate) Beads and Composite Particles containing Carbon Black with Hydrophobic Silica as a Stabilizer in Aqueous Solution

Abstract

ABSTRACT：A suspension copolymerization of styrene and butyl methacrylate (BMA) in the aqueous phase was conducted at a selected temperature between 65 and 95 ℃. Hydrophobic silica was selected as a stabilizer and azobisisobutyronitrile (AIBN) as an initiator. Optimum dispersion of silica in water was obtained at pH 10 while polymerization reaction was run at pH 7. TGA and EDS measurements revealed that 90% of silica functioned as a stabilizer and 10% were incorporated into polymeric particles. Average particle diameter decreased with increasing amounts of stabilizer. Molecular weights displayed an increase when the stabilizer concentration reached 1.67 wt%. An increase in the initiator concentration and/or reaction temperature raised the reaction rate but decreased molecular weights. Particle diameter was nearly independent of the initiator concentration and reaction temperature. An increase in the BMA proportion decreased the glass transition temperature and increased the particle diameter with irregularity in shape. Incorporation of carbon black into the particles composed of styrene and BMA prolonged the reaction time before reaching completion. We have confirmed that a suspension copolymerization of styrene and BMA with hydrophobic silica as a stabilizer can produce spherical composite particles with 1-30 ㎛ in diameter containing carbon black. 요 약：물을 반응매체로 하고 스티렌과 부틸메타크릴레이트 (BMA)를 단량체로 하여 65℃에서 95℃ 사이의 선택된 온도에서 현탁중합을 실시하였다. 소수성 실리카를 안정제로, azobisisobutyronirile (AIBN)을 개시제로 선택하였다.