title: Preparation of cross-linked biocompatible poly(2-methacryloyloxyethyl phosphorylcholine) gel and its strange swelling behavior in water/ethanol mixture.
abstract: Functional cross-linked poly(2-methacryloyloxyethyl phosphorylcholine(MPC)) gels were prepared with various cross-linkers by conventional radical polymerization in aqueous media. The poly(MPC) gels swelled in water and have a large degree of swelling compared with that of poly(2-hydroxyethyl methacrylate). The swelling degree of the poly(MPC) gel equilibrated in water depended on the chemical structure and composition of the cross-linkers, but did not change in an aqueous medium with pH and ionic concentrations. On the other hand, the volume of poly(MPC) gel changed sharply with a change in the composition of water/ethanol mixtures. Although in mixtures containing 70-90 vol% of ethanol the gel volume was nearly 10% of that in water, in pure ethanol it was almost the same as in water. The change in the volume of the poly(MPC) gel observed in a water/ethanol mixture was completely reversible. We conclude that this so-called re-entrant phenomenon was derived from the co-nonsolvency of poly(MPC) in the water/ethanol mixture triggered by an imbalance in the delicate interaction force between the molecules of water, ethanol, and poly(MPC).
authors.affiliation: Department of Materials Engineering, School of Engineering, The University of Tokyo, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Kiritoshi
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Ishihara
mesh_terms: D000178:Acrylamides / Q000494:pharmacology; D000179:Acrylates / Q000494:pharmacology; D001672:Biocompatible Materials / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D000431:Ethanol / Q000737:chemistry / Q000494:pharmacology; D005782:Gels / Q000737:chemistry; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007477:Ions; D008689:Methacrylates / Q000737:chemistry* / Q000494:pharmacology; D008956:Models, Chemical; D010084:Oxidation-Reduction; D010767:Phosphorylcholine / Q000031:analogs & derivatives* / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000494:pharmacology; D011109:Polymethacrylic Acids / Q000494:pharmacology; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D000178:Acrylamides; D000179:Acrylates; D001672:Biocompatible Materials; D003432:Cross-Linking Reagents; D005782:Gels; D007477:Ions; D008689:Methacrylates; D011109:Polymethacrylic Acids; C115766:poly(2-methacryloyloxyethyl-phosphorylcholine); D014867:Water; D010767:Phosphorylcholine; C020946:triethylene glycol dimethacrylate; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D000431:Ethanol; D011092:Polyethylene Glycols; C004919:ethylene dimethacrylate; C021221:N,N'-methylenebisacrylamide