The article by Kazuhiko ISHIHARA, Tomoko UEDA, and Nobuo NAKABAYASHI from the Institute for Medical and Dental Engineering at Tokyo Medical and Dental University discusses the preparation and properties of phospholipid polymers, specifically poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate) (MPC-co-BMA), as polymer hydrogel membranes. The authors improved the synthesis method of MPC, a methacrylate monomer with a phospholipid polar group, to achieve good yield. The copolymerization of MPC with n-butyl methacrylate (BMA) was successful, and the resulting polymer membranes were prepared using a solution casting method. These membranes exhibited excellent water absorption, forming hydrogel structures even at low MPC mole fractions (0.04). The water content of the hydrogel increased with the number of MPC units and temperature. The hydrogel membranes allowed the passage of water-soluble organic compounds and proteins with molecular weights below 10^4, but not those above 10^5. The study highlights the potential of these materials as biocompatible biomaterials, particularly in biomedical applications such as drug delivery, sensors, and separation membranes.The article by Kazuhiko ISHIHARA, Tomoko UEDA, and Nobuo NAKABAYASHI from the Institute for Medical and Dental Engineering at Tokyo Medical and Dental University discusses the preparation and properties of phospholipid polymers, specifically poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate) (MPC-co-BMA), as polymer hydrogel membranes. The authors improved the synthesis method of MPC, a methacrylate monomer with a phospholipid polar group, to achieve good yield. The copolymerization of MPC with n-butyl methacrylate (BMA) was successful, and the resulting polymer membranes were prepared using a solution casting method. These membranes exhibited excellent water absorption, forming hydrogel structures even at low MPC mole fractions (0.04). The water content of the hydrogel increased with the number of MPC units and temperature. The hydrogel membranes allowed the passage of water-soluble organic compounds and proteins with molecular weights below 10^4, but not those above 10^5. The study highlights the potential of these materials as biocompatible biomaterials, particularly in biomedical applications such as drug delivery, sensors, and separation membranes.