Patent ID: 8404783

Claim:
An actinically or thermally crosslinkable prepolymer that is obtained by: (a) making a copolymerization product by copolymerizing a polymerizable mixture to obtain a copolymer with first functional groups, wherein the polymerizable mixture comprises a first hydrophilic monomer, at least one polysiloxane-containing crosslinker, a chain transfer agent having a first functional group, a second hydrophilic monomer; and (b) reacting an organic compound having a second functional group with the copolymerization product to form the crosslinkable prepolymer having ethylenically unsaturated groups, wherein the organic compound comprises an ethylenically unsaturated group, wherein the second functional group of the organic compound reacts with one of the first functional groups of the copolymerization product, wherein the second hydrophilic monomer is present in an amount sufficient to produce a resultant prepolymer which, after purification, can be crosslinked actinically or thermally to form a silicone hydrogel material, wherein the second hydrophilic monomer has a free radical chain reaction slower than that of the first hydrophilic monomer, wherein the first hydrophilic monomer is (C 1 -C 4 -alkyl)acrylamide, N,N-di-(C 1 -C 4 -alkyl)acrylamide, or mixture thereof, wherein the second hydrophilic monomer selected from the group consisting of 2-hydroxyethyl acrylate (HEA), glycidyl methacrylate (GMA), N-vinylpyrrolidone (NVP), acrylic acid (AA), and a C 1 -C 4 -alkoxy polyethylene glycol (meth)acrylate having a weight average molecular weight of from 200 to 1500, wherein the silicone hydrogel material having about 10% or less of non-volatile extractables, wherein the polysiloxane-containing crosslinker is a polysiloxane of formula wherein R 6 , R 6 ′, R 7 and R 7 ′ are each methyl, d 1 is an integer from 10 to 300, (alk) is linear or branched C 2 -C 6 alkylene or a radical —(CH 2 ) 1-3 —O—(CH 2 ) 1-3 —, X is —O— or —NH— and Q is a radical of the formula