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Copolymerization of Lactide and Cyclic Carbonate via Highly Stereoselective Catalysts To Modulate Copolymer Sequences
Macromolecules ( IF 5.1 ) Pub Date : 2018-01-18 00:00:00 , DOI: 10.1021/acs.macromol.7b02696 Xinli Liu 1 , Xiufang Hua 1, 2 , Dongmei Cui 1
Macromolecules ( IF 5.1 ) Pub Date : 2018-01-18 00:00:00 , DOI: 10.1021/acs.macromol.7b02696 Xinli Liu 1 , Xiufang Hua 1, 2 , Dongmei Cui 1
Affiliation
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The controlled ring-opening polymerizations of enantiopure (L-LA or D-LA) or racemic lactide (rac-LA) with achiral functionalized cyclic carbonates (TMCR) have been performed by using the aminobisphenolate yttrium and lutetium alkyl complexes or an organo-base catalyst DBU (1,8-diazabicyclo[5.4.0]undec-7-ene), in combination with various alcohols as chain transfer agents. When using the highly heteroselective precatalyst 1Y, the copolymerization of rac-LA and TMCR afforded tapered copolymer poly(rac-LA-t-TMCR), while the copolymerization of enantiopure L-LA or D-LA, respectively, with TMCR gave pseudo-random product poly(L-LA-r-TMCR). When the low heteroselective rare-earth metal precatalysts or organic DBU were applied, the difference in the monomer distributions for the above two systems disappeared gradually. On the contrary, the monomer sequence distribution was not influenced by the types of chain transfer agents and TMCR. The kinetics study revealed that the competitive reaction ratios were rL-LA = 0.58 and rTMCR1 = 0.70 for the copolymerization of L-LA and TMCR1 while rrac-LA = 2.29 and rTMCR1 = 0.51 for the copolymerization of rac-LA and TMCR1, which were reasonably explained by the synergistic effect of high heteroselectivity of catalyst and better coordination capability of LA than other monomers.
中文翻译：
丙交酯和环状碳酸酯通过高度立体选择性催化剂的共聚反应，以调节共聚物的序列
对映纯（L-LA或D-LA）或外消旋丙交酯（rac -LA）与非手性官能化环状碳酸酯（TMC R）的受控开环聚合反应是通过使用氨基双酚盐钇和alkyl烷基络合物或有机-碱催化剂DBU（1,8-二氮杂双环[5.4.0]十一碳-7-烯），与各种醇结合用作链转移剂。当使用高度异质选择的预催化剂1 Y时，rac -LA和TMC R的共聚得到了渐缩共聚物聚（rac -LA- t -TMC R），而对映体纯的L-LA或D-LA与TMC进行了共聚。[R给出伪随机积poly（L-LA- r -TMC R）。当使用低杂选择性稀土金属预催化剂或有机DBU时，上述两种体系的单体分布差异逐渐消失。相反，单体序列分布不受链转移剂和TMC R的类型的影响。动力学研究显示，竞争反应比为[R L-LA = 0.58和- [R TMCR1 = 0.70 L-LA和TMC的共聚R1而ř外消旋-LA = 2.29和- [R TMCR1 = 0.51的共聚外消旋-LA和TMC R1可以合理地解释为催化剂的高杂种选择性和LA比其他单体具有更好的配位能力。
更新日期：2018-01-18
中文翻译：
丙交酯和环状碳酸酯通过高度立体选择性催化剂的共聚反应，以调节共聚物的序列
对映纯（L-LA或D-LA）或外消旋丙交酯（rac -LA）与非手性官能化环状碳酸酯（TMC R）的受控开环聚合反应是通过使用氨基双酚盐钇和alkyl烷基络合物或有机-碱催化剂DBU（1,8-二氮杂双环[5.4.0]十一碳-7-烯），与各种醇结合用作链转移剂。当使用高度异质选择的预催化剂1 Y时，rac -LA和TMC R的共聚得到了渐缩共聚物聚（rac -LA- t -TMC R），而对映体纯的L-LA或D-LA与TMC进行了共聚。[R给出伪随机积poly（L-LA- r -TMC R）。当使用低杂选择性稀土金属预催化剂或有机DBU时，上述两种体系的单体分布差异逐渐消失。相反，单体序列分布不受链转移剂和TMC R的类型的影响。动力学研究显示，竞争反应比为[R L-LA = 0.58和- [R TMCR1 = 0.70 L-LA和TMC的共聚R1而ř外消旋-LA = 2.29和- [R TMCR1 = 0.51的共聚外消旋-LA和TMC R1可以合理地解释为催化剂的高杂种选择性和LA比其他单体具有更好的配位能力。
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