New materials for contact lenses prepared from Si- and Ti-alkoxides by the sol-gel process

Methods of synthesizing materials for hard contact lenses were developed by hydrolysis and condensation of an epoxide substituted alkoxysilane and Ti-alkoxides. To enforce sufficient tensile strength, polymethacrylates were incorporated as linear crosslinking elements using a methacryloxy substituted alkoxysilane as a hook between the siliceous network and the polymer chain. The incorporation of titania led to dense monolithic products which could be cured only with some minor shrinkages. Good wettabilities [contact angles with water: (25 ± 5)°] are due to glycol groupings formed by the epoxide radicals. O 2 -permeabilities of P = (13 ± 1) × 10 −11 ml O 2 cm 2 ml −1 s −1 mm Hg −1 result from the silicone-like structure elements, where R denotes a silicon-carbon bound organofunctional radical.