Liquid-Crystalline Comb Polymers with Polystyrene Main Chain and Liposarcosine Side Chains

In order to show that liquid-crystallinity is a general property of comb like polymers with polyvinylic main chains and lipopeptidic side chains we have synthesized comb like polymers with polystyrene main chains and liposarcosine side chains by polymerization of styryl-liposarcosine macromonomers. The macromonomers were prepared in 3 steps: in the first step, chloromethyl styrene was transformed into styrylacetic acid; in the second step, styrylacetic acid was linked at the alpha end of an omega protected alpha,omega-aliphatic diamine; in the third step, the unblocked omega-amino group was used to initiate the polymerization of the N-carboxyanhydride of sarcosine. Then the macromonomers were transformed into comb polymers by radical polymerization. Our comb polymers exhibit mesophases in the dry state and in water concentrated solution. X-ray diffraction studies have shown that our comb polymers exhibit, in the absence of solvent a lamellar (Smectic A) mesophase, and in water concentrated solution two types of mesophases: lamellar and cylindrical hexagonal. The respective influence of the water concentration and the degree of polymerication p of the sarcosine on the type, the domain of stability and the geometrical parameters of the mesophases has been established. Comparison with comb polymers with polyacrylamide main chain and liposarcosine side chains has demonstrated the influence of the nature of the main chain.