| abstract |
Prepolymer (P) comprising a polyvinyl alcohol derivative with a molecular weight of at least ca. 2000 and containing ca. 0.5-80 % groups of formula (I) with respect to the number of OH groups : R = 1-8C alkylene ; R<1> = H or lower alkyl ; and R<2> = olefinic unsaturated electrophilic copolymerisable group preferably containing up to 25C atoms. Also claimed are (i) polymers prepared by photo-cross-linking of (P), optionally in the presence of additional vinyl monomers, (ii) the preparation of these polymers by the same method, (iii) moulded articles comprising these polymers, and (iv) the preparation of the moulded articles by photo-cross-linking (P), optionally in the presence of additional vinyl monomers, in a closed mould. |