Graft copolymerization of methyl methacrylate with an N-substituted maleimide-liquid-crystalline copolymer by atom transfer radical polymerization

The synthesis of novel copolymers consisting of a side-group liquid-crystalline backbone and poly (methyl methacrylate) grafts were realized by the use of atom transfer radical polymerization (ATRP). In the first stage, the bromine-functional copolymers 6-(4-cyanobiphenyl-4′-oxy)hexyl acrylate and (2,5-dioxo-2,5-dihydrolfi-pyrrole-l-yl)methyl 2-bromopropanoate were synthesized by free-radical polymerization. These copolymers were used as initiators in the ATRP of methyl methacrylate to yield graft copolymers. Both the macroinitiator and graft copolymers were characterized by ¹H-NMR, gel permeation chromatography, differential scanning calorimetry, and thermogravimetric analysis. The ATRP graft copolymerization was supported by an increase in the molecular weight of the graft copolymers compared to that of the macroinitiator and also by their monomodal molecular weight distribution.