Abstract: A process for the functionalisation of polymers is disclosed. Functionalisation takes place by reacting a polymer with a peroxidant, preferably, the peroxydisulphate or monosulphate or sodium or potassium in an aqueous medium. The hydroxylated polymer can then be reacted with other materials, including biomolecules. Using the method of the inventon, products eg. Catheters or oxygenators can be produced with improved properties hitherto unobtainable.

Abstract: A graft polymer obtainable by grafting a polymer substrate with a compound of formula (I), in which the groups R are the same or different and each is a straight or branched C.sub.1 -C.sub.4 alkyl group; X is an aryl group or a straight or branched C.sub.1 -C.sub.20 alkylene group, optionally containing one or more carbon-carbon double or triple bonds, ether linkages or aryl groups; the aryl groups being unsubstituted or substituted by one or more C.sub.1-4 alkyl groups; n is from 2 to 4; and A is a reactive group, is useful as a biocompatible material in contact lenses, biomedical devices and blood-containing devices. In a preferred embodiment A is a polymerizable group and the graft polymer is produced by radical initiated polymerization of the compound of formula (I) on the substrate which is initiated by a radical-forming group on the substrate.