High-molecular-weight aliphatic polycarbonates（APCs） were synthesized through a two-step transesterification process under solvent-free conditions. Oligomers with equal numbers of hydroxyl and phenyl carbonate termi...High-molecular-weight aliphatic polycarbonates（APCs） were synthesized through a two-step transesterification process under solvent-free conditions. Oligomers with equal numbers of hydroxyl and phenyl carbonate terminal groups could be easily controlled by using equimolar amounts of diphenyl carbonate（DPC） and aliphatic diols as feedstocks in the first step. In the second step, the high-molecular-weight APCs can be obtained by connecting -OH with -OC（O）OC6H5 end-group upon removing the generated phenol at reduced pressure. Mg（OAc）2 was found to be the best catalyst for this process among the screened catalysts, which gave the poly（l,4-butylene carbonate）（PBC） a weight-average molecular weight（Mw） of 148600 and a yield of 84.8% under its suitable reaction conditions. In addition, based on the results of X-ray diffraction（XRD）, scanning electron microscopy（SEM） and fourier transform infrared spectroscopy（FTIR）, a possible reaction mechanism over Mg（OAe）2 was proposed for APCs synthesis.展开更多
Some methods have been developed to use CO2 as the raw material to produce degradable polymeric materials.The terpolymer of carbonate（PPGC） synthesized with the terpolymerization of CO2,propylene oxide and γ-butyro...Some methods have been developed to use CO2 as the raw material to produce degradable polymeric materials.The terpolymer of carbonate（PPGC） synthesized with the terpolymerization of CO2,propylene oxide and γ-butyrolactone（GBL）.GBL offered an ester structural unit making the copolymer easier to hydrolyze.Hence, PPCG should be of good degradability.In order to study its degradability,the polymer PPCG was used as materials for drag loading.The drug-loaded microspheres were obtained by the W/O/W type emulsions method. The microspheres were spherical in shape with smooth surfaces and good dispersion. The drug loading and encapsulation efficiency were 36.7% and 78.6%, respectively. The degradative behave was studied by SEM, XRD and drug release curves in different degradation medium were obtained.It was found that these microspheres could be degraded at faster speed in the basic media, while could not be degraded in the acidic media.The higher pH value of the medium was,the faster the initial degradative speed was.展开更多
A new degradable aliphatic poly(butylene-co-e-caprolactone carbonate) (PBCL) was synthesized through the terpolymerization of carbon dioxide, 1,2-butylene oxide (BO) and e-caprolactone (CL), a polymer supported bimeta...A new degradable aliphatic poly(butylene-co-e-caprolactone carbonate) (PBCL) was synthesized through the terpolymerization of carbon dioxide, 1,2-butylene oxide (BO) and e-caprolactone (CL), a polymer supported bimetallic complex (PBM) was used as a catalyst. The terpolymers prepared were characterized by FT-IR,1H NMR, 13C NMR, WXRD and DSC. The hydrolysis tests were carried out to appraise the degradability of the copolymers.展开更多
文摘High-molecular-weight aliphatic polycarbonates（APCs） were synthesized through a two-step transesterification process under solvent-free conditions. Oligomers with equal numbers of hydroxyl and phenyl carbonate terminal groups could be easily controlled by using equimolar amounts of diphenyl carbonate（DPC） and aliphatic diols as feedstocks in the first step. In the second step, the high-molecular-weight APCs can be obtained by connecting -OH with -OC（O）OC6H5 end-group upon removing the generated phenol at reduced pressure. Mg（OAc）2 was found to be the best catalyst for this process among the screened catalysts, which gave the poly（l,4-butylene carbonate）（PBC） a weight-average molecular weight（Mw） of 148600 and a yield of 84.8% under its suitable reaction conditions. In addition, based on the results of X-ray diffraction（XRD）, scanning electron microscopy（SEM） and fourier transform infrared spectroscopy（FTIR）, a possible reaction mechanism over Mg（OAe）2 was proposed for APCs synthesis.
文摘Some methods have been developed to use CO2 as the raw material to produce degradable polymeric materials.The terpolymer of carbonate（PPGC） synthesized with the terpolymerization of CO2,propylene oxide and γ-butyrolactone（GBL）.GBL offered an ester structural unit making the copolymer easier to hydrolyze.Hence, PPCG should be of good degradability.In order to study its degradability,the polymer PPCG was used as materials for drag loading.The drug-loaded microspheres were obtained by the W/O/W type emulsions method. The microspheres were spherical in shape with smooth surfaces and good dispersion. The drug loading and encapsulation efficiency were 36.7% and 78.6%, respectively. The degradative behave was studied by SEM, XRD and drug release curves in different degradation medium were obtained.It was found that these microspheres could be degraded at faster speed in the basic media, while could not be degraded in the acidic media.The higher pH value of the medium was,the faster the initial degradative speed was.
文摘A new degradable aliphatic poly(butylene-co-e-caprolactone carbonate) (PBCL) was synthesized through the terpolymerization of carbon dioxide, 1,2-butylene oxide (BO) and e-caprolactone (CL), a polymer supported bimetallic complex (PBM) was used as a catalyst. The terpolymers prepared were characterized by FT-IR,1H NMR, 13C NMR, WXRD and DSC. The hydrolysis tests were carried out to appraise the degradability of the copolymers.
