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. Th...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.展开更多
The halogen-terminated polymers （PS—X） were obtained by living free radical polymerization. Through the end-group transformation action of AgClO4, poly（styrene-b-2-methyl-2-oxazoline） block copolymer [P（s-b-Me-...The halogen-terminated polymers （PS—X） were obtained by living free radical polymerization. Through the end-group transformation action of AgClO4, poly（styrene-b-2-methyl-2-oxazoline） block copolymer [P（s-b-Me-OXZ）] was synthesized by transforming the living free radical polymerization into ring-opening polymerization of 2-methyl-2-oxazoline.The obtained copolymers were characterized by SEC, IR and 1H NMR. The suitable polymerization conditions for block copolymer synthesis were studied.展开更多
文摘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.
文摘The halogen-terminated polymers （PS—X） were obtained by living free radical polymerization. Through the end-group transformation action of AgClO4, poly（styrene-b-2-methyl-2-oxazoline） block copolymer [P（s-b-Me-OXZ）] was synthesized by transforming the living free radical polymerization into ring-opening polymerization of 2-methyl-2-oxazoline.The obtained copolymers were characterized by SEC, IR and 1H NMR. The suitable polymerization conditions for block copolymer synthesis were studied.
