Bindings of a Secondary Polymer to Monodisperse Colloidal Silica Particles Modified with Poly(maleic anhydride–styrene) for Controlling the Surface Polarity

Abstract

Abstract A polymer modification of monodisperse colloidal silica (120 nm in diameter) and control of the surface polarity were studied. The binding of poly(maleic anhydride–styrene) to the silica particles and successive grafting of amino-terminated polymethacrylates with methyl, hexyl, and dodecyl ester groups afforded unimodal composite particles, which were dispersible in a low-polar solvent of ethyl acetate. The bindings of the secondary polymer were dependent on the molecular structure of the polymer as well as the reaction conditions. The surface polarity was estimated by aggregation of the particles in an ethyl acetate–methanol cosolvent, monitored by the absorbance of a suspension containing the composite particles at 500 nm. The polarity was significantly affected by the main chain length of the secondary polymer of the polymethacrylates rather than the bound polymer chain number or the branch alkyl ester group of the polymer. For highly modified composite particles, it was observed that the carboxyl group, simultaneously formed in the binding of the secondary polymer, contributed to the surface polarity.