Synthesis of novel polybutadiene-graft-poly(sodium methacrylate) amphiphilic copolymers as precursors for liquid crystalline graft copolymers

Well-defined polybutadiene-graft-poly(tert-butyl methacrylate) (PBD-g-PtBMA) copolymers were prepared by reaction of PtBMA chains end-capped with a tert-butyl 4-vinylbenzoate (tBVB) anion, with the selectively hydrosilylated 1,2-units of anionically synthesized PBD. Substitution of the tBVB anion for the anion of living PtBMA chains is required for the formation of the expected C-silylation product instead of the unstable O-silylation one. Subsequent hydrolysis of the poly(tert-butyl methacrylate) grafts followed by neutralization of the carboxylic acid groups by sodium hydroxide leads to amphiphilic polybuta-diene-graft-poly(sodium methacrylate) (PBD-g-PNaMA) graft copolymers. These copolymers form unimeric micelles in water, as observed by dynamic light scattering (DLS). Non-covalent liquid crystalline graft copo-lymers were prepared by cation exchange between PBD-g-PNaMA copolymers and an ammonium containing smectic mesogen. These copolymers form a smectic mesophase which is microphase separated from PBD.