A polymerizable electrolyte, 2-aminoethyl 1,6-heptadien-4-yl phosphate (AEHDP), which has the same hydrophilic head group as naturally occurring phospholipids, was prepared. Five equivalents of AEHDP were added to a suspension of liposomes (closed bilayer vesicles made of phospholipids) and layered on the liposomes. After polymerization by UV irradiation, the resulting polymer-coated liposomes were resistant to hydrolysis of their constituent phospholipids by phospholipase A(2).