CHAIN-EXTENDED UV-CURABLE WATERBORNE POLYURETHANE-ACRYLATE

Conventional and chain-extended UV-curable waterborne polyurethane-acrylate (PUA) ionomer were prepared from diisocyanate,polyethylene glycol(PEG) ,dimethylol- propionic acid(DMPA) ,hydroxyethyl methacrylate(HEMA) . The two kinds of PUA prepolymer could be easily dispersed in water in the form of self-emulsified latex after the carboxyl group at- taching to the backbone of PUA was neutralized with tertiary amine.The effects of M n of PEG, carboxyl content on the interfacial tension and rheological behavior of PUA dispersions were in- vestigated. The chain-extended PUA prepolymer could photopolymerize to a greater extent than conventional one as indicated by differential photocalorimetry.The differential scanning calorime- try(DSC) analysis for photocured films from PUA dispersions suggested that higher M n of PEG would provoke phase separation phase mixing between soft and hard segment phases.