Poly(N,N-dimethylaminoethyl methacrylate) [poly(DMAEMA)] was grafted onto a commercial polyethylene film by means of gamma-irradiation, and the grafted films were reacted with various liquid-crystal-forming benzoic acids. When polymeric salts consisting only of poly(DMAEMA) and the benzoic acids were heated, dissociation of salts was observed, but with poly(DMAEMA) grafted onto polyethylene films, salt dissociation or crystallization of dissociated acids could be avoided, and interesting morphologies, including liquid-crystal phases, were observed for the systems of benzoic acids-poly(DMAEMA-g-polyethylene).