tailieunhanh - Báo cáo vật lý: "Emulsion Polymers of Core-Shell Styrene-Butyl Acrylate: The Effect of Feeding and Aging Time on Particle Size Distribution"

Tuyển tập các báo cáo nghiên cứu khoa học trên tạp chí khoa học vật lý quốc tế đề tài: Emulsion Polymers of Core-Shell Styrene-Butyl Acrylate: The Effect of Feeding and Aging Time on Particle Size Distribution | Journal of Physical Science Vol. 19 2 117-125 2008 117 Emulsion Polymers of Core-Shell Styrene-Butyl Acrylate The Effect of Feeding and Aging Time on Particle Size Distribution Helmiyati and Emil Budianto Department of Chemistry FMIPA University of Indonesia Depok 16424 Indonesia Corresponding author Helmi-yt@ Abstract Core-shell polymers in the particle size range 200-300 nm having a monodisperse distribution and opal color are prospective materials for coating applications. The emulsion polymerization of the core-shell was done using two monomers with significantly different refractive indices styrene for the hard monomers and butyl acrylate for the soft monomers. The feeding and aging time were varied with particle size shown to increase with decreasing feeding time. Increasing the aging time increased conversion but had no effect to the particle size even after two hours producing particles in the 200-300 nm range. The obtained core-shell emulsion polymers were characterized by determining particle size and polymers morphology by TEM. Keywords core-shell emulsion styrene-butyl acrylate particle size feeding time aging time color effect 1. INTRODUCTION The ability to control particle properties like size and morphology has increased research interest in emulsion polymerization. The desired outcome depends on the physical properties of starting polymers such as glass transition temperature and chemical properties structure and monomer chain Polymers are used to effect color in coating application and monomer type and polymerization technique are important controlling parameters. There has been much research done in this area. One method to control color is by selective reflection usually accomplished with chemical dyes containing chromophore groups. The color effect from polymers core-shells is caused by the 111 plane reflection of the face-centered cubic fcc lattice. Particle diameter must be 200 D 300 nm so that the light will be reflected in .