Synthesis of high refractive index acrylic copolymers

Abstract

A series of brominated carbazole-containing monomers with a polymerizable acrylic or methacrylic functionality were synthesized and characterized. These monomers were polymerized thermally and characterized by differential scanning calorimetry (DSC) and refractive index via Brewster's angle. The monomer 4-(1,3,6,8-tetrabromo-9-carbazolyl)-1-butyl acrylate (4b) was copolymerized with methyl methacrylate (M₂) yielding the reactivity ratiosr₁= 1.08 and r₂= 0.93; these values were used in the Skeist procedure to predict compositional drift with conversion. The Alfrey–Price Q and e values for (4b) were 0.86 and 0.46, respectively. The copolymers were all colourless and transparent, despite the absence of an azeotrope for this comonomer pair, and their refractive indices were found to lie between those of the constituent homopolymers. Copolymers rich in methyl methacrylate (MMA) were found to be soluble, yet those rich in 4b were found to be intractable.