The susceptibility of poly(ether)urethanes to enzymatic degradation after oxidative pretreatment

Susceptibility of poly(ether)urethanes (PEU) to hydrolytic degradation by enzymes after a limited exposure to free radicals was investigated. Two PEU, one chain extended with 1,4-butanediol and the other chain extended with 2-butene-1,4-diol, were used as model polymers. Each material was subjected to treatments including oxidative, enzymatic (with papain), and oxidative followed by enzymatic treatment. The degradative effect on surfaces was examined by optical microscopy, attenuated total reflectance infrared spectroscopy as well as XPS. It was found that enzymatic degradation occurred only after certain amount of oxidative change had been initiated. This was probably associated with enzyme adsorption on surfaces pre-exposed to oxidation. The extent of overall degradation was strongly influenced by the oxidation stability of the materials. PEU chain extended with 2-butene-1,4-diol was more resistant to oxidation, and hence less susceptible to enzymatic degradation. It was concluded that exposure of PEU to oxidative pretreatment increased its susceptibility to hydrolysis by enzymes, and that oxidation followed by enzymatic attack could be the biodegradation mechanism of PEU in vivo. (C) 1999 Elsevier Science Ltd. All rights reserved.