Competition between Liquid-liquid De-mixing, Crystallization, and Glass Transition in Solutions of PLA of Different Stereochemistry and DEET  

作　　者：Chanita Sungkapreecha Walter WFocke Rene Androsch 

机构地区：[1]Interdisciplinary Center for Transfer-oriented Research in Natural Sciences,Martin Luther University Halle-Wittenberg,06099 Halle/Saale,Germany [2]University of Pretoria Institute for Sustainable Malaria Control and MRC Collaborating Centre for Malaria Research,Department of Chemical Engineering,University of Pretoria,Private Bag X20,Hatfield 0028,South Africa

出　　处：《Chinese Journal of Polymer Science》2020年第2期174-178,I0007,共6页高分子科学（英文版）

基　　金：financially supported by Deutsche Forschungsgemeinschaft (DFG) (No. AN 212/22)

摘　　要：Liquid-liquid(L-L)de-mixing and vitrification of solutions of either crystallizable poly(L-lactic acid)(PLLA)or non-crystallizable poly(D/L-lactic acid)(PDLLA)with 50 m%N,N-diethyl-3-methylbenzamide(DEET)were analyzed by calorimetry and cloud-point measurements,which allows drawing conclusions about the effect of polymer stereochemistry on the phase behavior.Regardless of the PLA stereochemistry,vitrification of the solutions on fast cooling,hindering crystallization of PLLA,occurred below-20℃ and suppressed prior L-L de-mixing.The experimental results prove that crystallization in samples containing crystallizable PLLA,observed at around 55℃ on slow cooling,is not preceded by L-L de-mixing.Liquid-liquid(L-L) de-mixing and vitrification of solutions of either crystallizable poly(L-lactic acid)(PLLA) or non-crystallizable poly(D/L-lactic acid)(PDLLA) with 50 m% N,N-diethyl-3-methylbenzamide(DEET) were analyzed by calorimetry and cloud-point measurements,which allows drawing conclusions about the effect of polymer stereochemistry on the phase behavior. Regardless of the PLA stereochemistry,vitrification of the solutions on fast cooling, hindering crystallization of PLLA, occurred below-20 °C and suppressed prior L-L de-mixing. The experimental results prove that crystallization in samples containing crystallizable PLLA, observed at around 55 °C on slow cooling, is not preceded by L-L de-mixing.

关 键 词：CRYSTALLIZATION PLA DEET Liquid-liquid phase separation Thermally-induced phase separation(TIPS) 

分 类 号：O631.3[理学—高分子化学]