Abstract: Polylactic acid is an important biodegradable material which has diversified applications in our daily life. We designed and synthesized six Schiff base ligands with hemilabile side arm oxygen or sulfide (L1—L6) and their corresponding complexes (C1—C6) by the reaction with tetraisopropyl titanate. The structures of the complexes were identified by elemental analysis and infrared spectroscopy. The catalytic performance in lactide ring-opening polymerization were carefully examined. Different polymerization conditions such as catalyst concentration, temperature, polymerization time as well as the catalyst structures were investigated in order to study their influences on the polymerization behaviors towards lactide with C1 as a typical example. We found the polymer yield reached the highest level of 90.35% and the molecular weight of the polymer reached 8.41×104 g/mol at molar ratio of monomer to catalyst of 2 000 at 160 ℃ for 24 h. The catalyst activity decreased in the order of C6>C4>C3>C1>C2>C5 at the optimal conditions. The less bulkiness of catalyst environment around the metal center and the hemilability of the side arm which has weaker coordination ability and are both beneficial to improve the activity.
1 Jiang A J. Research on the performance and preparation of sisal fibers reinforced polylacticacid composites[D]. Guangzhou: South China University of Technology,2012(in Chinese). 姜爱菊. 剑麻纤维增强聚乳酸复合材料的制备及性能研究[D]. 广州:华南理工大学,2012. 2 Zhao Y M, Zhang J, Mai H Z. Study on the direct polycondensation of polylactic acid[J].Synth Fiber China,2001,30(3):3(in Chinese). 赵耀明, 张军, 麦杭珍. 直接缩聚法合成聚乳酸的研究[J]. 合成纤维,2001,30(3):3. 3 Achmad F, Yamane K, Quan S, et al. Synthesis of polylactic acid by direct polycondensation under vacuum without catalysts, solvents and initiators[J]. Chem Eng J,2009,151(1):342. 4 Wang Z Y, Zhao Y M, Mai H Z, et al. Study on the direct synthetic of polylactic acid Through melt polycondensation[J]. Synth Fiber China,2002,31(2):11(in Chinese). 汪朝阳, 赵耀明, 麦杭珍, 等. 熔融聚合法直接合成聚乳酸的研究[J]. 合成纤维,2002,31(2):11. 5 Thakur K A M, Kean R T, Hall E S, et al. High-resolution 13C and 1H solution NMR study of poly(lactide)[J]. Macromolecules,1997,30(8):2422. 6 Kricheldorf H R, Berl M, Scharnagl N. Poly(lactones). 9. polymerization mechanism of metal alkoxide initiated polymerizations of lactide and various lactones[J]. Macromolecules,1988,21(2):286. 7 Huang X P. Synthesis of lactide and polylactic acid[J]. Guangdong Chem Ind,2014,41(5):56(in Chinese). 黄晓萍. 丙交酯与聚乳酸的合成[J]. 广东化工,2014,41(5):56. 8 Liu H, Wang X J, Zhang L X. Synthesis of high molecular weight poly lactic acid by lactidering-opening polymerization[J]. Guangzhou Chem Ind,2015,46(7):124 (in Chinese). 刘辉, 王肖杰, 张留学. 丙交酯开环聚合法合成高分子量聚乳酸[J]. 广州化工,2015,46(7):124. 9 Liu Z. The synthesis of main group metal complexes supp-orted by β-ketoiminato ligands and their catalytic behaviors on the polymerization of PLA[D]. Wuxi: Jiangnan University,2013(in Chinese). 刘臻. β-酮亚胺基主族金属配合物的制备和催化聚乳酸[D]. 无锡: 江南大学,2013. 10 Wu J. Syntheses, structures and catalytic properties of sulfobenzoate titanium complexes[D].Hangzhou:Zhejiang University,2015(in Chinese). 吴静. 磺基苯甲酸钛配合物的合成、结构及催化性质研究[D].杭州: 浙江大学,2015. 11 Li X, Hu C B, Fu Y, et al. Ring-opening polymerization of D,L-lactide to synthesize polylactic acid catalyzed by schiff-base titanium complex[J]. J Funct Mater,2011,42(10):1772(in Chinese). 李香, 胡承波, 傅亚, 等. 希夫碱钛配合物催化D,L-丙交酯本体开环合成聚乳酸[J]. 功能材料,2011,42(10):1772. 12 Lindner R, Bosch B V D, Lutz M, et al. Tunable Hemilabile Ligands for adaptive transitionmetal complexes[J]. Organometallics,2011,30(3):499. 13 Gareau D, Suiseng C, Groux L F, et al. Indenyl-nickel complexes bearing a pendant, hemilabile olefin ligand: Preparation, characte-rization, and catalytic activities[J].Organometallics,2005,24(16):4003. 14 Cunningham D, McArdle P, Mitchell M, et al. Adduct formation between alkali metal ions and divalent metal salicylaldimine complexes having methoxy substituents. A structural investigation[J]. Inorg Chem,2000,39(8):1639. 15 Raya L, Katiyarb V, Barman S, et al. Gold(I)N-heterocyclic carbene based initiators for bulk ring-opening polymerization of L-lactide[J]. J Organometallic Chem,2007,692(20):4259. 16 Yang J J. Polymerization of styrene and isoprene with rare earth schiff base complexes[D]. Hangzhou: Zhejiang University,2006(in Chinese) 杨建江. 稀土希夫碱配合物催化苯乙烯、异戊二烯聚合[D]. 杭州: 浙江大学,2006. 17 Li J F. Gas phase polymerization of conjugated dienes with supported rare earth catalyst: kinetics and molecular weight control[D]. Hangzhou:Zhejiang University,2002(in Chinese). 李俊菲. 双烯烃气相聚合-聚合动力学和分子量控制研究[D]. 杭州: 浙江大学,2002. 18 Hu M G, Wang F G, Cao Q B, et al. Synthesis and catalytic beha-viors of a new Ti complex supported by unsymmetric N, O ligand[J].J Qiqihar University,2015,31(6):58(in Chinese). 胡明刚, 王富贵, 曹清彬, 等. 对称氮氧配体钛配合物合成及催化丙交酯开环聚合研究[J]. 齐齐哈尔大学学报,2015,31(6):58. 19 Hu C B, Fu Y, Xiang H Z, et al. Rop of D,L-lactide catalyzed by bis(alkoxy-imine-phenoxy) titanium(Ⅳ) complex: Kinetic and mechanism[J]. Acta Chim Sin,2011,69(21):2574(in Chinese). 胡承波, 傅亚, 向鸿照, 等. 双(烷氧-亚胺芳氧)基钛(Ⅳ)配合物催化D,L-丙交酯开环聚合、动力学及机理[J]. 化学学报,2011,69(21):2574.
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2017, Vol. 31 
