聚己内酯-聚醚嵌段共聚物的光降解特性与机理

聚己内酯-聚醚嵌段共聚物(PCE)是一种可生物降解的高聚物[1].我们已经报道了PCE在体内及体外的降解特性,发现PCE的降解速度随着共聚物中聚醚含量的增加,温度升高,介质的酸碱性和酶的存在而加快.当PCE植入于动物体内,它的降解速度大大加快,因此PCE是一种极具应用前景的生物医用材料[2,3].

PHOTODEGRADATION BEHAVIOR AND MECHANISM OF POLYCAPROLACTONE-POLY(ETHYLENE OXIDE) BLOCK COPOLYMER

The biodegradation behavior in vitro and in vivo of polycaprolactone poly (ethylene oxide) block copolymers ( P C E) has been reported in detail. Photodegradation testof P C E was performed by exposure to U Vlight. The mechanical properties and the inherentviscosity of P C Esamples which are subjected to photodegradation were determined . Thephotodegradation rate of P C E was much more faster than its hydrolysis rate and wasincreased with increasing poly(ethylene oxide) content. The experimental results alsoindicated that the pure poly(ethylene oxide) ( P E O) can not be photodegraded alone. Amechanism forthe photodegradation of P C Ecopolymers was proposed :thecarbonylgroupsin P C Lsegmentscatalyze the breakage ofthe P E Ochains by a seriesof U Vinitiated freeradicalreactions. When the free radicals induce the degradation of P E O segments in P C E,thephotodegradation of P C E mainly occursin P E Osegments.