Polymers

A process for the manufacture of a moulding, comprising the steps of:

• A) providing a mold for making the moulding;
• B) introduce a solution into the mold, wherein the solution comprises
• (i) one or more crosslinkable prepolymers which are obtained by ultrafiltration,
• (ii) one or more solvents selected from the group consisting of a C1-C6-alkanol, a glycol, a carboxylic acid amide, dimethyl sulfoxide and water,
• wherein each of said one or more crosslinkable prepolymer is obtained by
• (a) copolymerizing at least one hydrophilic monomer having one first ethylenically unsaturated group and at least one crosslinker comprising two or more second ethylenically unsaturated groups in the presence of a chain transfer agent comprising a chain transfer group and a first reactive group to obtain a copolymerization product with first reactive groups, wherein said at least one crosslinker is a polysiloxane, a perfluoroalkyl polyether, or a polysiloxane/perfluoroalkyl polyether block copolymer, wherein the hydrophilic monomer is a monomer which, when polymerized, gives a homopolymer which is water-soluble or can absorb at least 10% by weight of water, and
• (b) reacting an organic compound with the copolymerization product to form the crosslinkable or polymerizable prepolymer having third ethylenically unsaturated groups, wherein the organic compound comprises a third ethylenically unsaturated group and a second reactive group, wherein the second reactive group of the organic compound reacts with one of the first reactive groups of the copolymerization product,
• wherein each of said one or more crosslinkable prepolymer is substantially free of monomeric, oligomeric or polymeric starting compounds used for the preparation of the prepolymer, and/or free of secondary products formed during the preparation of the prepolymer, wherein said solution is substantially free of comonomers;
• and
• C) crosslinking said one or more crosslinkable prepolymers to form the moulding.