PREPARATION OF 2-METHACRYLOYLOXYETHYL PHOSPHORYLCHOLINE COPOLYMERS WITH ALKYL METHACRYLATES AND THEIR BLOOD COMPATIBILITY

Copolymers having the phospholipid polar group, 2-methacryloyloxyethyl phosphorylcholine (MPC) and alkyl methacrylates (n-butyl, tert-butyl, n-hexyl, n-dodecyl, and n-stearyl groups) were synthesized. The characteristics of these copolymers and blood cell adhesion on the copolymers were investigated. Solubility in various solvents, glass transition temperature, and swelling degree in water depended not only on their MPC composition but also on alkyl groups of the comonomer. Copolymer surfaces were equilibrated in water within a day except for poly(MPC-co-n-stearyl methacrylate), which was confirmed by dynamic contact angle measurements. Deposition of fibrin and adhesion of blood cells on the MPC copolymers after contact with whole blood were strongly influenced by MPC composition and chemical structure of the copolymer, but there was no relationship between surface free energy and blood compatibility. The blood compatibility of these MPC copolymers also changed based on the substrate membrane which was coated with the MPC copolymers. That is, when poly(n-butyl methacrylate) was used as the substrate membrane, poly(MPC-co-n-dodecyl methacrylate) did not show good blood compatibility, whereas the blood compatibility of the copolymer was improved on a polyethylene substrate. The affinity of MPC copolymers to the substrate is thought to be one of the dominant factors that determine the blood compatibility of the copolymers.