Photo-induced crosslinking of water-soluble polymers with a new photobase generator

A strong bicyclic guanidine base, 1,5,7-triaza-bicyclo[4.4.0]dec-5-ene (TBD), is photo-generated from its tetraphenylborate salt (TBD·HBPh4) and can effectively catalyze the transesterification reaction between the ester and hydroxy groups in polymers. Accordingly, with TBD·HBPh4 as a photobase generator, a water-soluble polymer blend, namely poly(1-vinylpyrrolidone-co-2-dimethylaminoethyl methacrylate) and 2-hydroxyethyl cellulose, has been developed as a potential eco-friendly photoresist. This photoresist system uses only water as a solvent and as a developer, rather than organic solvents and aqueous alkaline developers. The effects of the amount of photobase generator, polymer composition and photolithographic conditions on the photo-induced crosslinking and patterning of water-soluble polymers were studied.