BILAYER STRUCTURES IN SIDE-CHAIN LC COPOLYMERS

Random copolymers AxB1-x of two comonomers having sufficiently long and different side chains can form double comb conformations wherein the two types of side chains are demixed. These copolymers can build up bilayer structures, with alternating layers filled by the side chains of A and B. The structures and transition temperatures of such copolymers were studied, by DSC, light microscopy, and X-ray scattering. The main chain is always methacrylic; the side chains consist of spacer decoupled mesogens or of n-alkyl sequences. Three rings in the mesogenic side chains and ten methylene groups in the alkyl side chains are required for good bilayer structures. Calculations show that the bilayer structure is not hindered by the random comonomer sequence order in the AxB1-x chains, unless x is very large or small.