Poly(3-vinylphenyl selenocyanate) and poly(4-vinylphenyl selenocyanate): synthesis and photocrosslinking

Two new monomers, 3-vinylphenyl selenocyanate and 4-vinylphenyl selenocyanate, were synthesized from 3- and 4-aminoacetophenone as starting materials. Free radical polymerization of the monomers gave poly(3-vinylphenyl selenocyanate) and poly(4-vinylphenyl selenocyanate) as fully soluble and stable materials. The polymers became crosslinked upon 254 nm UV irradiation. The photolysis of phenyl selenocyanate in heptane and cumene solution gave diphenyl diselenide as the main product. The photo-cleavage of SeCN groups into phenylseleno and cyano radicals also occurred in the polymers. Photo-crosslinking data were processed with the Charlesby-Pinner relation. The quantum efficiencies Phi(CL) of crosslinking were 0.053 (+/-0.020) for poly(3-vinylphenyl selenocyanate) and 0.071 (+/-0.026) for poly(4-vinylphenyl selenocyanate), the quantum efficiencies Phi(CS) of chain scission were 85.10(-4) (+/-59.10(-4)) and 25.10(-4) (+/-25.10(-4)), respectively. A comparison with data on other polystyrene derivatives showed that poly(3-vinylphenyl selenocyanate) and poly(4-vinylphenyl selenocyanate) are highly sensitive negative resists in the polystyrene series.