Ophthalmic devices containing localized grafted networks and processes for their preparation and use

Abstract

Provided are polymer compositions made by a process comprising: (a) providing a first reactive composition containing: (i) a polymerization initiator that is capable, upon a first activation, of forming two or more free radical groups, at least one of which is further activatable by subsequent activation; (ii) one or more ethylenically unsaturated compounds; and (iii) a crosslinker; (b) subjecting the first reactive composition to a first activation step such that the first reactive composition polymerizes therein to form a crosslinked substrate network containing a covalently bound activatable free radical initiator; (c) contacting the crosslinked substrate network with a grafting composition containing one or more ethylenically unsaturated compounds, wherein the contacting is conducted under conditions such that the grafting composition penetrates into the crosslinked substrate network; and (d) activating the covalently bound activatable free radical initiator at one or more selective regions of the crosslinked substrate network such that the grafting composition polymerizes with the crosslinked substrate network at the selective regions.