Method of making formpieces, formpiece made thereby, prepolymers suitable for use according to said method, network polymers, homo- or copolymers obtained from such prepolymers, method of obtaining said prepolymers and network polymers, homo- or copolymers obtained from them,l formpieces made of said homo- or copolymers and method of making said formpieces using homo- or copolymers

The invention relates to a novel process for the production of mouldings, in particular contact lenses, in which a soluble prepolymer containing crosslinkable groups is crosslinked in solution, and to mouldings, in particular contact lenses, obtainable by this process. The present invention likewise relates to novel prepolymers which can be employed in the novel process, in particular derivatives of a polyvinyl alcohol having a molecular weight of at least about 2000 which contains from about 0.5 to about 80%, based on the number of hydroxyl groups in the polyvinyl alcohol, of units of the formula I, <IMAGE> in which R is lower alkylene having up to 8 carbon atoms, R<1> is hydrogen or lower alkyl, and R<2> is an olefinically unsaturated, electron-withdrawing (electron-attracting), copolymerisable radical, preferably having up to 25 carbon atoms, to crosslinked polymers, either homopolymers or copolymers, made from these new prepolymers, to a process for the preparation of the novel prepolymers and the homopolymers and copolymers obtainable therefrom, to mouldings made from said homopolymers or copolymers, in particular contact lenses made from these homopolymers or copolymers, and to a process for the production of contact lenses using said homopolymers or copolymers.