LASER-LIGHT-SCATTERING STUDIES ON THE COMPLEXATION BETWEEN POLY(STYRENE-CO-4-VINYLPHENOL) AND ISOREFRACTIVE POLY(ETHYL METHACRYLATE) IN TOLUENE

Laser-light-scattering (LLS) studies on the complexation between poly( styrene-co-4-vinylphenol) (STVPh) and isorefractive poly(ethyl methacr ylate) (PEMA) in toluene show that the complexes can form immediately after mixing two complementary polymer solutions. The time dependence of the excess scattering intensity and average hydrodynamic radius ([R (h)]) indicates that the STVPh/PEMA complex dispersion is not thermody namically stable in toluene. Only if one of the components is in exces s can more stable complex dispersion be obtained. When the phenol cont ent of STVPh is higher than 9 mol %, the composition dependence of [R( h)] shows a maximum at an equimolar ratio of monomer STVPh to EMA, cor responding to the fixed mean stoichiometry (FMS) ratio of complexation determined by viscometry. A combination of static and dynamic LLS res ults reveals that the complex particles are more compact than individu al polymer chains and the complexes have a fixed composition when the amount of STVPh15 is in excess, wherein each PEMA polymer chain acts a s a nucleus surrounded by similar to 35 STVPh15 polymer chains, sugges ting a sterically controlled complexation process.