An efficient route to macrocyclic polymers via “click” cyclization was presented.The α-bromine and ω-alkyne PMMA were prepared using the standard ATRP technique,initiated with propargyl 2-bromoisobutyrate,Cu(Ⅰ)Br...An efficient route to macrocyclic polymers via “click” cyclization was presented.The α-bromine and ω-alkyne PMMA were prepared using the standard ATRP technique,initiated with propargyl 2-bromoisobutyrate,Cu(Ⅰ)Br and N,N,N’,N″,N-pentamethyldiethylenetriamine(PMDETA).Azidation of the terminal bromine was followed in DMF with sodium azide,and α-azide,ω-alkyne PMMA precursor was obtained.Then the “click” cylcization of precursor between terminal azide and alkyne was carried out under the catalysis of CuBr/PMDETA,during the course of the reaction,a pseudo-high dilution technique was utilized to ensure the favored intramolecular cylcization.The nearly complete cylcization has been confirmed by a combination of IR,1H NMR and GPC analysis,and cyclo-PMMA with an Mn of 15000,PDI of 1.38 was obtained.展开更多
Poly(methyl methacrylate)(PMMA)pellets are irradiated using 60Co gamma-ray in air and successfully formed by hot pressing at constant conditions.The irradiated PMMA membranes are prepared by supercritical carbon dioxi...Poly(methyl methacrylate)(PMMA)pellets are irradiated using 60Co gamma-ray in air and successfully formed by hot pressing at constant conditions.The irradiated PMMA membranes are prepared by supercritical carbon dioxide(scCO2)as a physical blowing agent using the pressure quench method.Effects of foaming conditions such as adsorbed dose,saturation temperature,pressure on the morphology and cell size of the microcellular PMMA membranes are investigated in detail.The results showed that the irradiated PMMA membranes possess spherically closed-cell structure with uniform cell size.They have a high cell density compared with virgin PMMA.The cell size uniformity becomes poor at dose lower than 10 kGy,but increases with the dose at dose higher than 10 kGy.The mean cell diameter is less than 10μm and the cell density increases with increasing dose.The average cell size of irradiated PMMA membranes decreases and cell density increases with increased saturation temperature and pressure.The changes in morphology of membranes are attributed to the gamma-ray radiation and scCO2synergistic effect.展开更多
文摘An efficient route to macrocyclic polymers via “click” cyclization was presented.The α-bromine and ω-alkyne PMMA were prepared using the standard ATRP technique,initiated with propargyl 2-bromoisobutyrate,Cu(Ⅰ)Br and N,N,N’,N″,N-pentamethyldiethylenetriamine(PMDETA).Azidation of the terminal bromine was followed in DMF with sodium azide,and α-azide,ω-alkyne PMMA precursor was obtained.Then the “click” cylcization of precursor between terminal azide and alkyne was carried out under the catalysis of CuBr/PMDETA,during the course of the reaction,a pseudo-high dilution technique was utilized to ensure the favored intramolecular cylcization.The nearly complete cylcization has been confirmed by a combination of IR,1H NMR and GPC analysis,and cyclo-PMMA with an Mn of 15000,PDI of 1.38 was obtained.
基金Supported by the National Natural Science Foundation of China(Nos.11005148,and 11079048)Science and Technology Commission of Shanghai Municipality(No.11JC1414900)+2 种基金the Natural Science Foundation of Guangxi University of Technology(No.1166107)Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA01020304)the project of Urban and rural housing construction in Anhui province(No.2012YF-08)
文摘Poly(methyl methacrylate)(PMMA)pellets are irradiated using 60Co gamma-ray in air and successfully formed by hot pressing at constant conditions.The irradiated PMMA membranes are prepared by supercritical carbon dioxide(scCO2)as a physical blowing agent using the pressure quench method.Effects of foaming conditions such as adsorbed dose,saturation temperature,pressure on the morphology and cell size of the microcellular PMMA membranes are investigated in detail.The results showed that the irradiated PMMA membranes possess spherically closed-cell structure with uniform cell size.They have a high cell density compared with virgin PMMA.The cell size uniformity becomes poor at dose lower than 10 kGy,but increases with the dose at dose higher than 10 kGy.The mean cell diameter is less than 10μm and the cell density increases with increasing dose.The average cell size of irradiated PMMA membranes decreases and cell density increases with increased saturation temperature and pressure.The changes in morphology of membranes are attributed to the gamma-ray radiation and scCO2synergistic effect.
