THE ROLE OF BULKY POLYSILOXANYLALKYL METHACRYLATES IN POLYURETHANE-POLYSILOXANE HYDROGELS

Silicone hydrogels based on polyurethane-polysiloxane prepolymers and hydrophilic monomers such as N,N-dimethylacrylamide, although possessi ng high oxygen permeability and satisfactory tear strength, are too st iff to be targeted for applications such as contact lenses. However, w ith the inclusion of bulky polysiloxanylalkyl methacrylates, such as m ethacryloxypropyl tris(trimethylsiloxy)silane (TRIS), to replace part of the polyurethane prepolymer, the hydrogels obtained not only mainta ined high oxygen permeability, but also had a lower modulus and improv ed tear strength. These changes in properties are all favorable for ap plications such as oxygen-permeable hydrogel lenses. (C) 1996 John Wil ey & Sons, Inc.