Preparation and crystallization kinetics of new structurally well-defined star-shaped biodegradable poly(L-lactide)s initiated with diverse natural sugar alcohols

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	Preparation and crystallization kinetics of new structurally well-defined star-shaped biodegradable poly(L-lactide)s initiated with diverse natural sugar alcohols
	Hao QH(郝庆辉) ; Li FX(李发学) ; Li QB(李巧波) ; Li Y(李洋) ; Jia L(贾林) ; Yang J(杨晶) ; Fang Q(房强) ; Cao AM(曹阿民)
刊名	Biomacromolecules
	2005
卷号	6 期号:4 页码:2236-2247
ISSN号	1525-7797
其他题名	新型结构规整型星状生物降解性聚乳酸的合成与结晶动力学研究
通讯作者	曹阿民
英文摘要	This study presents syntheses, structural characterization, and crystallization kinetic investigation of new structurally well-defined star-shaped poly(L-lactide)s (PLLAs). First, a series of new 3- to 6-arm star-shaped PLLAs were synthesized through SnOct(2) catalyzed ring-opening polymerization of (L)-lactide with natural sugar alcohols of glycerol, erythritol, xylitol, and sorbitol as the favorable initiators. Subsequently, their chemical structures were characterized by means of GPC, NMR, and viscometer with respect to the star-shaped structures, demonstrating the well-defined arm structures as evidenced on the g(1/2)/g' values, where g and g' denote the ratios of mean-square radius of gyration and intrinsic viscosity of a star-shaped polymer to those of a linear structural reference with similar absolute molecular weight. Furthermore, spherulite morphologies and growth rates were studied by a polarized microscopy (POM) for the synthesized starshaped PLLAs with different molecular weights, and it was found that the more arms of a star-shaped PLLA finally resulted in a lower spherulite growth rate. With regard to the crystallization kinetics of these star-shaped PLLAs, isothermal and nonisothermal crystallization were examined by differential scanning calorimeter DSC. It was found that Avrami exponent n values of isothermal crystallization were almost independent of the isothermal crystallization temperature T, for different series of star-shaped PLLAs. In contrast, the values of Avrami exponent n were observed to strongly depend on the star-shaped structures with different arms, implying their distinct nucleation mechanisms, and the more arms of a star-shaped PLLA led to a slower isothermal crystallization rate. On the basis of a modified Avrami equation, new light was shed on the nonisothermal crystallization kinetics for the star-shaped PLLAs, and the activation energies were found to vary from 146.86 kJ/mol for the linear PLLA EG-3 to 221.23 kJ/mol of the star-shaped S-3, demonstrating much decreased crystallizabilities of star-shaped PLLAs with more arms.
学科主题	高分子化学
收录类别	SCI
原文出处	http://dx.doi.org/10.1021/bm050213m
语种	英语
WOS记录号	WOS:000230498400056
公开日期	2013-03-07
内容类型	期刊论文
源URL	[http://202.127.28.38/handle/331003/22894]
专题	上海有机化学研究所_高分子材料研究室
推荐引用方式 GB/T 7714	Hao QH,Li FX,Li QB,et al. Preparation and crystallization kinetics of new structurally well-defined star-shaped biodegradable poly(L-lactide)s initiated with diverse natural sugar alcohols[J]. Biomacromolecules,2005,6(4):2236-2247.
APA	郝庆辉.,李发学.,李巧波.,李洋.,贾林.,...&曹阿民.(2005).Preparation and crystallization kinetics of new structurally well-defined star-shaped biodegradable poly(L-lactide)s initiated with diverse natural sugar alcohols.Biomacromolecules,6(4),2236-2247.
MLA	郝庆辉,et al."Preparation and crystallization kinetics of new structurally well-defined star-shaped biodegradable poly(L-lactide)s initiated with diverse natural sugar alcohols".Biomacromolecules 6.4(2005):2236-2247.