Laser-Light-Scattering Studies on the Complexation between Poly(styrene-<i>co</i>-4-vinylphenol) and Isorefractive Poly(ethyl methacrylate) in Toluene

Abstract

Laser-light-scattering (LLS) studies on the complexation between poly(styrene-co-4-vinylphenol) (STVPh) and isorefractive poly(ethyl methacrylate) (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 (〈Rh〉) indicates that the STVPh/PEMA complex dispersion is not thermodynamically stable in toluene. Only if one of the components is in excess can more stable complex dispersion be obtained. When the phenol content of STVPh is higher than 9 mol %, the composition dependence of 〈Rh〉 shows a maximum at an equimolar ratio of monomer STVPh to EMA, corresponding to the fixed mean stoichiometry (FMS) ratio of complexation determined by viscometry. A combination of static and dynamic LLS results reveals that the complex particles are more compact than individual polymer chains and the complexes have a fixed composition when the amount of STVPh15 is in excess, wherein each PEMA polymer chain acts as a nucleus surrounded by ∼35 STVPh15 polymer chains, suggesting a sterically controlled complexation process.