An nanostructured thermoset blend of unsaturated polyester(UPR) and PEO-PPO-PEO triblock copolymer was prepared and characterized by solid-state NMR and other techniques.It is concluded that the blend is microphase se...An nanostructured thermoset blend of unsaturated polyester(UPR) and PEO-PPO-PEO triblock copolymer was prepared and characterized by solid-state NMR and other techniques.It is concluded that the blend is microphase separated and the determined long period is 20 nm.A distinct dynamic difference between the cured-UPR matrix and block copolymers was observed by 1D and 2D NMR experiments,the formation of PEO crystalline domains was inhibited in the blend.The PEO blocks are partially miscible with the cured-UPR matrix.Upon curing, part of the mobile PEO was locally expelled from the cured-UPR matrix and formed dispersed microphase together with the mobile PPO,the residual immobilized PEO blocks were intimately mixed with the partially cured-UPR, and they formed an interphase region.展开更多
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
文摘An nanostructured thermoset blend of unsaturated polyester(UPR) and PEO-PPO-PEO triblock copolymer was prepared and characterized by solid-state NMR and other techniques.It is concluded that the blend is microphase separated and the determined long period is 20 nm.A distinct dynamic difference between the cured-UPR matrix and block copolymers was observed by 1D and 2D NMR experiments,the formation of PEO crystalline domains was inhibited in the blend.The PEO blocks are partially miscible with the cured-UPR matrix.Upon curing, part of the mobile PEO was locally expelled from the cured-UPR matrix and formed dispersed microphase together with the mobile PPO,the residual immobilized PEO blocks were intimately mixed with the partially cured-UPR, and they formed an interphase region.
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.
