Preparation and Physical Properties of a Silicone Hydrogel Contact Lens Grafted with a Phosphorylcholine-Containing Hydrophilic Copolymer

Silicone hydrogel contact lenses (SiH CLs) covalently grafted with a high-water-content copolymer layer, poly(2-methacryloyloxyethyl phosphorylcholine-co-2-hydroxyethyl acrylate) [P(MPC-co-HEA)], were fabricated, and their physical properties were investigated. SiH CLs were first prepared by radical copolymerization of a siloxane monomer and hydrophilic comonomers, and they were exposed to oxygen plasma to create peroxide groups on the lens surfaces. By letting peroxide-containing (O 2 -plasma-treated) SiH CLs act as a thermal free radical initiator, the P(MPC-co-HEA) layer with a water content of approximately 87% could be incorporated onto the surface by graft copolymerization between the lenses and mixed monomers (MPC and HEA). A P(MPC-co-HEA)-grafted SiH CL showed a contact angle of 49.9°, decreased from that of a pristine SiH CL (89.6°). The oxygen permeability of the P(MPC-co-HEA)-grafted SiH CL was recorded to be 54.46 barrer, almost the same as that of the pristine SiH CL (56.01 barrer). Meanwhile, the optical transmittance, tensile strength, and thermal characteristics of the P(MPC-co-HEA)-grafted SiH CL did not deteriorate following the O 2 plasma treatment and graft copolymerization.