poly acrylamide co 3 methacrylamidopropylacrylamide poly vinylalcohol monomethacrylate poly vinylalcohol monoacrylate poly vinylalcohol dimethacrylate and the like such macromers can be prepared for instance by first synthesizing a hydrophilic polymer of the desired molecular weight followed by a polymer modification step to introduce the desired level of polymerizable e g vinyl functional units for example acrylamide can be copolymerized with specific amounts of 3 aminopropylmethacrylamide comonomer and the resulting copolymer can then be modified by reaction with methacrylic anhydride to introduce the methacrylamide functional units thereby producing a useful macromer for purposes of this invention poly ethylene glycol of a desired molecular weight can be synthesized or purchased from a commercial source and modified e g by reaction with methacrylyl chloride or methacrylic anhydride to introduce the terminal methacrylate ester units to produce a macromer useful in the process of this invention some applications can benefit by use of macromers with the polymerizable units located at or near the terminus of the polymer chains whereas other uses can benefit by having the polymerizable unit s located along the hydrophilic polymer chain backbone such monomeric and macromeric polymerizable molecules can be used alone or in combination with each other including for instance combinations of macromers.