A rigid silica colloidal crystal template was formed by self assembly of the monodispersed silica dispersion prepared according to Stber method. Within the interstitial void of the template, β diketonate titanium com...A rigid silica colloidal crystal template was formed by self assembly of the monodispersed silica dispersion prepared according to Stber method. Within the interstitial void of the template, β diketonate titanium complexes[(dbm) 3Ti(OPh)/MAO] catalyzed polymerization of styrene was carried out to form syndiotactic polystyrene(sPS)/silica composites. The titled ordered macroporous syndiotactic polystyrene was achieved by chemical decomposition of the silica template with concentrated aqueous hydrofluoric acid, which was confirmed by SEM results. FTIR spectra indicated that all silica was removed from the composites in this study. DSC revealed that the as prepared macroporous sPS was significantly different from the bulk one, and the unique properties were inherent rather than from the enforcement effect by the silica template. Further investigation concerning the inherent microstrucutures about the molecular weight and its distribution, tacticity of the styrene etc . and their dependence on the confinement is in progress.展开更多
间规聚苯乙烯 (s PS)是近年来发展起来的一种具有广阔应用前景的新型工程塑料 ,茂金属催化剂是合成 s PS最主要的催化剂 ,它主要是由茂金属主催化剂和甲基烷氧基铝等助催化剂组成 ,具有单一的活性中心和催化效率高等特点。文中介绍了近...间规聚苯乙烯 (s PS)是近年来发展起来的一种具有广阔应用前景的新型工程塑料 ,茂金属催化剂是合成 s PS最主要的催化剂 ,它主要是由茂金属主催化剂和甲基烷氧基铝等助催化剂组成 ,具有单一的活性中心和催化效率高等特点。文中介绍了近年来各种茂金属催化剂 ,包括组成、特点。展开更多
Half sandwich titanocenes, e.g . (ind)TiRCl 2 (R—Cl, OMe, OEt; ind—indenyl group) and β diketonate titanium complexes, e.g . (dbm) 3TiL (L—Cl, OPh, OPhMe; dbm—dibenzoylmethane group) were investigated for syndiot...Half sandwich titanocenes, e.g . (ind)TiRCl 2 (R—Cl, OMe, OEt; ind—indenyl group) and β diketonate titanium complexes, e.g . (dbm) 3TiL (L—Cl, OPh, OPhMe; dbm—dibenzoylmethane group) were investigated for syndiotactic polymerization of styrene. The optimum molar ratios of Al to Ti of β diketonate titanium complexes were different from those of mono indenyl titanium complexes. The polymerization activity of (ind)TiRCl 2 was higher than that of (dbm) 3TiL at their own optimum n (Al)/ n (Ti). Compared with (ind)TiRCl 2, the thermostability of (dbm) 3TiL was higher. The polymerization activity of (dbm) 3Ti(OPh) was 6 5×10 5 g/(mol·h) at 363 K, while that of (ind)Ti(OMe)Cl 2 was only 4 9×10 5 g/(mol·h) at the same temperature. After 2 h of polymerization, the reaction activity of the nontitanocene was remained at 6×10 5 g/(mol·h), while that of the half sandwich titanocene was only 0 71×10 5 g/(mol·h). It is indicated that the life time of (dbm) 3TiL was much longer than that of (ind)TiRCl 2. The melting temperatures ( T m) and the syndiotacticity of polystyrene by β diketonate titanium complexes were higher than those of the polymer by mono indenyl titanium complexes as well.展开更多
文摘A rigid silica colloidal crystal template was formed by self assembly of the monodispersed silica dispersion prepared according to Stber method. Within the interstitial void of the template, β diketonate titanium complexes[(dbm) 3Ti(OPh)/MAO] catalyzed polymerization of styrene was carried out to form syndiotactic polystyrene(sPS)/silica composites. The titled ordered macroporous syndiotactic polystyrene was achieved by chemical decomposition of the silica template with concentrated aqueous hydrofluoric acid, which was confirmed by SEM results. FTIR spectra indicated that all silica was removed from the composites in this study. DSC revealed that the as prepared macroporous sPS was significantly different from the bulk one, and the unique properties were inherent rather than from the enforcement effect by the silica template. Further investigation concerning the inherent microstrucutures about the molecular weight and its distribution, tacticity of the styrene etc . and their dependence on the confinement is in progress.
文摘Half sandwich titanocenes, e.g . (ind)TiRCl 2 (R—Cl, OMe, OEt; ind—indenyl group) and β diketonate titanium complexes, e.g . (dbm) 3TiL (L—Cl, OPh, OPhMe; dbm—dibenzoylmethane group) were investigated for syndiotactic polymerization of styrene. The optimum molar ratios of Al to Ti of β diketonate titanium complexes were different from those of mono indenyl titanium complexes. The polymerization activity of (ind)TiRCl 2 was higher than that of (dbm) 3TiL at their own optimum n (Al)/ n (Ti). Compared with (ind)TiRCl 2, the thermostability of (dbm) 3TiL was higher. The polymerization activity of (dbm) 3Ti(OPh) was 6 5×10 5 g/(mol·h) at 363 K, while that of (ind)Ti(OMe)Cl 2 was only 4 9×10 5 g/(mol·h) at the same temperature. After 2 h of polymerization, the reaction activity of the nontitanocene was remained at 6×10 5 g/(mol·h), while that of the half sandwich titanocene was only 0 71×10 5 g/(mol·h). It is indicated that the life time of (dbm) 3TiL was much longer than that of (ind)TiRCl 2. The melting temperatures ( T m) and the syndiotacticity of polystyrene by β diketonate titanium complexes were higher than those of the polymer by mono indenyl titanium complexes as well.
