Synthesis of hydrophilic cross-linker having phosphorylcholine-like linkage for improvement of hydrogel properties

As a novel cross-linking reagent, dimethacrylate having a phosphorylcholine-like linkage, called 2-(methacryloyloxy)ethyl-[N-(2-methacryloyloxy)ethyl]phosphorylcholine (MMPC), was synthesized by condensation between methacrylate having a cyclic phosphate and that with a tertiary amine group. The MMPC was copolymerized with 2-methacyloyloxyethyl phosphorylcholine (MPC) or 2-hydroxyethyl methacrylate (HEMA) to produce the polymer hydrogels. The polymerization initiated by a redox system in aqueous medium proceeded well and the hydrogel was formed. The swelling of the poly(MPC) hydrogel was regulated by the MMPC composition. For the poly(HEMA) gel cross-linked with MMPC, the swelling degree was almost the same in the MMPC composition range of 1.0–10 mol%. However, the transparency of the poly(HEMA) gel increased with an increase in the MMPC. The MMPC is a useful cross-linker to make hydrogels and control the swelling and property of the hydrogel.