ALKOXY-SUBSTITUTED TITANIUM(IV) CHLORIDES AS LEWIS-ACID ACTIVATORS FOR LIVING CATIONIC POLYMERIZATION OF ISOBUTYL VINYL ETHER - CONTROL OF LEWIS-ACIDITY IN THE DESIGN OF INITIATING SYSTEMS
ALKOXY-SUBSTITUTED TITANIUM(IV) CHLORIDES AS LEWIS-ACID ACTIVATORS FOR LIVING CATIONIC POLYMERIZATION OF ISOBUTYL VINYL ETHER - CONTROL OF LEWIS-ACIDITY IN THE DESIGN OF INITIATING SYSTEMS
复制标题
DOI：
10.1021/ma00120a037
复制
发表时间：
1995-07-31
期刊：
影响因子：
5.5
通讯作者：
HIGASHIMURA, T
中科院分区：
文献类型：
--
作者：
KAMIGAITO, M;SAWAMOTO, M;HIGASHIMURA, T
以异丙氧基氯化钛[TiCl_4-n（OiPr）（n）; n = 0-4]为引发剂，在-15 ℃ CH_2Cl_2中与IBVE-HCl加成，制备了一种新的IBVE活性阳离子聚合钛引发体系。钛化合物的H-1和C-13 NMR分析表明，随着异丙氧基数目（n）的增加，其刘易斯酸性降低，从而影响聚合反应。例如，TiCl 4和TiCl 3（OiPr），这五种酸中最强的刘易斯酸，诱导非常快速的聚合，得到具有宽分子量分布（MWD）的聚合物（（$）相对于棒M（w）/（$）相对于棒M（n），类似于1.6）。相反，与TiCl 2（OiPr）（2）（一种较弱的刘易斯酸）的反应速率是中等的。聚合物的MWD在整个反应中是窄的（（$）对棒M（w）/（$）对棒M（n）< 1.2），并且数均分子量与单体转化率成正比地增加。用Ticl（OiPr）（3）的聚合较慢，并且MWD变得稍微更宽。用弱得多的刘易斯酸Ti（OiPr）（4）没有得到聚合物。另一种改性的氯化钛，TiCl 2（OPh）（2），也导致IBVE的受控聚合，这与TiCl 3（OiPr）（2）类似。这些结果表明，可以通过控制具有给电子基团的钛（IV）活化剂的刘易斯酸性来实现IBVE的活性阳离子聚合。
Titanium(TV)-based new initiating systems for living cationic polymerization of isobutyl vinyl ether (IBVE) have been developed by using a series of isopropoxytitanium chlorides [TiCl4-n(OiPr)(n); n = 0-4] in conjunction with the IBVE-HCl adduct in CH2Cl2 at -15 degrees C. The H-1 and C-13 NMR analysis of the titanium compounds showed that their Lewis acidity decreased with the increasing number (n) of isopropoxyl groups and affected the polymerizations accordingly. For example, TiCl4 and TiCl3(OiPr), the strongest Lewis acids among the five, induced very rapid polymerizations to give polymers with broad molecular weight distributions (MWDs) (($) over bar M(w)/($) over bar M(n) similar to 1.6). In contrast, the reaction rate with TiCl2(OiPr)(2), a weaker Lewis acid, was moderate. The MWDs of the polymers were narrow throughout the reaction (($) over bar M(w)/($) over bar M(n) < 1.2), and the number average molecular weights increased in direct proportion to monomer conversion. The polymerization with Ticl(OiPr)(3) was slower, and the MWDs became slightly broader. No polymer was obtained with a much weaker Lewis acid, Ti(OiPr)(4). Another modified titanium chloride, TiCl2(OPh)(2), also led to a controlled polymerization of IBVE which is similar to the one with TiCl3(OiPr)(2). These results indicate that living cationic polymerizations of IBVE can be achieved by controlling the Lewis acidity of the titanium(IV) activators with electron-donating groups.