Linear and star-shaped polylactides(PLA) with similar molecular weights of each arm are synthesized via ringopening polymerization of LA with 3-butyn-1-ol and pentaerythritol as initiators,respectively.By solution b...Linear and star-shaped polylactides(PLA) with similar molecular weights of each arm are synthesized via ringopening polymerization of LA with 3-butyn-1-ol and pentaerythritol as initiators,respectively.By solution blending of equivalent mass of poly(L-lactic acid)s(PLLAs) and poly(D-lactic acid)s(PDLAs),perfect PLA stereocomplexes(sc PLAs) are prepared and confirmed by WAXD and FTIR analysis.Effect of chain architectures on stereocomplex crystallization is investigated by studying the non-isothermal and isothermal crystallization of linear and star-shaped polylactide stereocomplexes.In dynamic DSC and POM test,star-shaped PLLA(4s PLLA)/PDLA and PLLA/star-shaped PDLA(4s PDLA) stereocomplexes reach rapid crystallization and higher crystallinity due to larger spherulite density of star-shaped chain and excellent chain mobility of linear chain.In isothermal crystallization test,much faster crystallization and less crystallization half-time is obtained with the increase of star-shaped chain.Meanwhile,4s PLLA/PDLA and PLLA/4s PDLA are found to have the highest crystallinity,suggesting limitation of too much star-shaped chain for 4s PLLA/4s PDLA and restriction of linear chain in nucleation capacity for PLLA/PDLA.The results reveal that star-shaped chain has an important influence on the crystallization of sc PLAs.展开更多
基金financially supported by the National High-Tech R&D Program of China(No.2013AA032202)the National Natural Science Foundation of China(No.51203118)+1 种基金the Fundamental Research Funds for the Central Universitiesthe Open Funds for Characterization of Tongji University
文摘Linear and star-shaped polylactides(PLA) with similar molecular weights of each arm are synthesized via ringopening polymerization of LA with 3-butyn-1-ol and pentaerythritol as initiators,respectively.By solution blending of equivalent mass of poly(L-lactic acid)s(PLLAs) and poly(D-lactic acid)s(PDLAs),perfect PLA stereocomplexes(sc PLAs) are prepared and confirmed by WAXD and FTIR analysis.Effect of chain architectures on stereocomplex crystallization is investigated by studying the non-isothermal and isothermal crystallization of linear and star-shaped polylactide stereocomplexes.In dynamic DSC and POM test,star-shaped PLLA(4s PLLA)/PDLA and PLLA/star-shaped PDLA(4s PDLA) stereocomplexes reach rapid crystallization and higher crystallinity due to larger spherulite density of star-shaped chain and excellent chain mobility of linear chain.In isothermal crystallization test,much faster crystallization and less crystallization half-time is obtained with the increase of star-shaped chain.Meanwhile,4s PLLA/PDLA and PLLA/4s PDLA are found to have the highest crystallinity,suggesting limitation of too much star-shaped chain for 4s PLLA/4s PDLA and restriction of linear chain in nucleation capacity for PLLA/PDLA.The results reveal that star-shaped chain has an important influence on the crystallization of sc PLAs.