CAJ | 학술논문

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、13C NMR谱、红外光谱和差式扫描量热器等进行表征.结果表明:聚合温度、单体对催化剂的浓度比和超临界二氧化碳纯度是关键因素,最佳聚合条件为温度85～90℃,c( LA)/c( SnOct2)为500～1 000,聚合时间48 h；辛酸亚锡是高效催化剂,但催化效率随影响因素而变；超临界二氧化碳流体中的聚合机理为配位插入聚合.
재초림계이양화탄류체중용신산아석작최화제,용좌선병교지개배취합성공지합성료상대분자질량대우80 000,분산지수위2.5적취좌선유산.심입연구료취합온도、시간、압력、단체농도、최화제용량급초림계이양화탄순도등각충인소대취좌선유산상대분자질량급기분포적영향,대취합물적상대분자질량화분포채용응효삼석색보、1HNMR보、13C NMR보、홍외광보화차식소묘량열기등진행표정.결과표명:취합온도、단체대최화제적농도비화초림계이양화탄순도시관건인소,최가취합조건위온도85～90℃,c( LA)/c( SnOct2)위500～1 000,취합시간48 h；신산아석시고효최화제,단최화효솔수영향인소이변；초림계이양화탄류체중적취합궤리위배위삽입취합.
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.