Novel Polymer Architectures via the Selective Polymerization of Lyotropic Liquid Crystals of Heterobifunctional Amphiphiles

The reactivity of polymerizable amphiphiles in supramolecular assemblies, such as lipid bilayers, is dependent on the mode of initiation, the polymerizable group, and the position of the reactive group in the amphiphile. This report describes the synthesis, characterization, and polymerization of a novel heterobifunctional lipid, 1-palmitoyl-2-(2,4,12,14-tetraenehexadecanoyl)phosphatidylcholine (1), that contains a diene and a dienoyl group in the sn-2 acyl chain. The difference in polarity of local sites of each group within the bilayer makes it possible to perform simultaneous or selective polymerizations of these groups. Simultaneous polymerization of both reactive groups was achieved by either redox polymerization or direct photoirradiation. Selective polymerization of the dienoyl was accomplished by photoirradiation with filtered light from a high-pressure Hg/Xe lamp. The diene was selectively initiated by thermal decomposition of AIBN. The degree of polymerization depended strongly on the initiation...