A series of electron donors,including 1,1-cyclopentanecarboxylic acid diethyl ester (CPCADEE),1,1cyclopentanedimethanol acetic diester (CPDMAD),1,1-biethoxymethyl pentane (BEMP),2,2-diethyl diethylmalonate (DEDEM)and ...A series of electron donors,including 1,1-cyclopentanecarboxylic acid diethyl ester (CPCADEE),1,1cyclopentanedimethanol acetic diester (CPDMAD),1,1-biethoxymethyl pentane (BEMP),2,2-diethyl diethylmalonate (DEDEM)and 2,2-diethyl-1,3-propanediol acetic diester (DEPDADE),were synthesized by diethyl malonate (DEM).The purities and structures of the above products were characterized by gas chromatography (GC) and gas chromatography-mass spectrometer (GC-MS),respectively.Furthermore,the possible optimal three-dimensional structures of these donors were simulated by means of Gaussian 03 and Chem 3D.Then these electron donors were coordinated with tetrachloro titanium (TiCl 4) and chloride magnesium (MgCl 2)to obtain the catalysts for the polymerization of propylene.The catalytic activities and properties of polypropylene are greatly improved by adding external donor(ED) when CPCADEE or DEPDADE is used as internal donor(ID).However,when BEMP was used as ID,the highest catalytic activity is obtained without adding ED,which can reduce production costs and simplify catalytic synthesis.The experiments indicate that BEMP has the shortest distance of oxygen atoms and the highest electronegativity.展开更多
Poly（ethylene glycol） methacrylate （PEGMA） was introduced into a polyurethane （PU） solution in order to prepare hemocom- patible electrospun membranes for potential application as small diameter vascular scaffol...Poly（ethylene glycol） methacrylate （PEGMA） was introduced into a polyurethane （PU） solution in order to prepare hemocom- patible electrospun membranes for potential application as small diameter vascular scaffolds. Crosslinked PU/PEGMA hybrid nanofibers were fabricated by a reactive electrospinning process with N,N＇-methylenebisacrylamide （MBAm） as erosslinker and benzophenone （BP） as photoinitiator. The photoinduced polymerization and crosslinking reaction took place simultane- ously during the electrospinning process. No significant difference in the membrane morphology was found by SEM when PEGMA content was less than 20 wt%. The crosslinked fibrous membranes of PU/PEGMA exhibit higher hydro- philicity and mechanical strength than PU membrane. These nanofibrous membranes are potential substitutes for artificial vascular scaffolds.展开更多
基金Supported by National Natural Science Foundation of China (No. 20476080)Tianjin Natural Science Foundation (No. 07JCYBJC00600)
文摘A series of electron donors,including 1,1-cyclopentanecarboxylic acid diethyl ester (CPCADEE),1,1cyclopentanedimethanol acetic diester (CPDMAD),1,1-biethoxymethyl pentane (BEMP),2,2-diethyl diethylmalonate (DEDEM)and 2,2-diethyl-1,3-propanediol acetic diester (DEPDADE),were synthesized by diethyl malonate (DEM).The purities and structures of the above products were characterized by gas chromatography (GC) and gas chromatography-mass spectrometer (GC-MS),respectively.Furthermore,the possible optimal three-dimensional structures of these donors were simulated by means of Gaussian 03 and Chem 3D.Then these electron donors were coordinated with tetrachloro titanium (TiCl 4) and chloride magnesium (MgCl 2)to obtain the catalysts for the polymerization of propylene.The catalytic activities and properties of polypropylene are greatly improved by adding external donor(ED) when CPCADEE or DEPDADE is used as internal donor(ID).However,when BEMP was used as ID,the highest catalytic activity is obtained without adding ED,which can reduce production costs and simplify catalytic synthesis.The experiments indicate that BEMP has the shortest distance of oxygen atoms and the highest electronegativity.
基金financially supported by the Program for New Century Excellent Talents in University "NCET"Ministry of Education of Chinathe International Cooperation from Ministry of Science and Technology of China (Grant No. 2008DFA51170)
文摘Poly（ethylene glycol） methacrylate （PEGMA） was introduced into a polyurethane （PU） solution in order to prepare hemocom- patible electrospun membranes for potential application as small diameter vascular scaffolds. Crosslinked PU/PEGMA hybrid nanofibers were fabricated by a reactive electrospinning process with N,N＇-methylenebisacrylamide （MBAm） as erosslinker and benzophenone （BP） as photoinitiator. The photoinduced polymerization and crosslinking reaction took place simultane- ously during the electrospinning process. No significant difference in the membrane morphology was found by SEM when PEGMA content was less than 20 wt%. The crosslinked fibrous membranes of PU/PEGMA exhibit higher hydro- philicity and mechanical strength than PU membrane. These nanofibrous membranes are potential substitutes for artificial vascular scaffolds.
