超临界二氧化碳流体中L-丙交酯开环聚合物的合成及表征

在超临界二氧化碳流体中用辛酸亚锡作催化剂,用左旋丙交酯开环聚合成功地合成了相对分子质量大于80 000,分散指数为2.5的聚左旋乳酸.深入研究了聚合温度、时间、压力、单体浓度、催化剂用量及超临界二氧化碳纯度等各种因素对聚左旋乳酸相对分子质量及其分布的影响,对聚合物的相对分子质量和分布采用凝胶渗析色谱、1HNMR谱、13...

Synthesis and Characterization of Polylactides by Ring-opening Polymerization of L-lactide in Supercritical Carbon Dioxide

Poly(L-lactides)with relatively high relative molecular mass,mass-average relative molecular mass more than 80 000 with polydispersity index (PDI) 2.5 measured by gel permeation chromatography,is successfully synthesized by ring-opening polymerization of L-lactides in supercritical carbon dioxide using stannous octoate as initiator.Various effects such as polymerization temperature,time,pressure,concentrations of monomer and catalyst,and purity of SC-CO2 on relative molecular mass of PLLA and relative molecular mass distribution as well as monomer conversion monitored with 1 H NMR spectroscopy are systematically investigated.It is found that polymerization temperature,monomer to catalyst molar ratio,and purity of caron dioxide are the key factors.The catalysis efficiency indicates that one SnOct2 molecule is able to initiate a number of polymer chains,which is varied with all effects.The experimental results are consistent with the coordination-insertion polymerization mechanism in which stannous alkoxide initiator is formed in situ via reaction between stannous octoate and traces of water present in carbon dioxide and catalyst.The resulting polymer is also characterized with 13C NMR,FT-IR and DSC.