Synthesis and Evaluation of Polystyrenes for Pigment Dispersant through ATRP Using Dimethyl 2,6-Dibromoheptanedioate as the Initiator

Abstract

Molecular weight-controlled polystyrenes (PS) were synthesized by the ATRP using dimethyl 2,6-dibromoheptanedioate as the initiator. The methoxy carbonyl groups were converted to carboxyl groups by alkaline hydrolysis. The interfacial tension between organic phase (xylene) and water phase (pH 6 or 8 phosphate buffer solution) decreased by addition of the amphiphilic PS containing two carboxyl groups. Moreover, the good dispersibility of the higher molecular weight PS containing carboxyl groups was confirmed by the measurement of rate of strain dependence on the viscosity of pigment dispersants such as phthalocyanine blue or iron oxide red. The improvement of the pigment dispersion was also obvious from microscopic observation.