Temperature‐induced spontaneous sol–gel transitions of poly(D,L‐lactic acid‐co‐glycolic acid)‐b‐poly(ethylene glycol)‐b‐poly(D,L‐lactic acid‐co‐glycolic acid) triblock copolymers and their end‐capped derivatives in water
Temperature‐induced spontaneous sol–gel transitions of poly(D,L‐lactic acid‐co‐glycolic acid)‐b‐poly(ethylene glycol)‐b‐poly(D,L‐lactic acid‐co‐glycolic acid) triblock copolymers and their end‐capped derivatives in water
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DOI：
10.1002/pola.21876
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发表时间：
2007-03
期刊：
影响因子：
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通讯作者：
Lin Yu;Guangtao Chang;Huanhua Zhang;Jiandong Ding
中科院分区：
文献类型：
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作者：
Lin Yu;Guangtao Chang;Huanhua Zhang;Jiandong Ding
观察到一种生物相容性和生物可降解性的两亲性嵌段共聚物在水中自发形成水凝胶，并推测了潜在的凝胶化机理。合成了一系列ABA型三嵌段共聚物[聚（D，L-乳酸-羟基乙酸）-b-聚（乙二醇）-b-聚（D，L-乳酸-羟基乙酸）]及不同的小烷基封端衍生物，并研究了这些样品的水相行为。原始的三嵌段共聚物和大多数衍生物在水中表现出温度依赖性的可逆溶胶-凝胶转变。聚（D，L-乳酸-羟基乙酸）的长度和端基被发现显着调整凝胶窗口的相图中，但有不同的行为。临界胶束浓度远低于相关的临界凝胶浓度，凝胶化后保持完整的胶束结构。各种测量技术的组合证实，溶胶-凝胶转变与温度的增加，诱导不仅通过两亲性聚合物链的自组装，但也通过胶束的进一步疏水聚集，导致胶束网络由于大规模的自组装。胶束网络的粗化被进一步认为是透明凝胶向不透明凝胶转变的原因。
The spontaneous hydrogel formation of a sort of biocompatible and biodegradable amphiphilic block copolymer in water was observed, and the underlying gelling mechanism was assumed. A series of ABA-type triblock copolymers [poly(D,L-lactic acid-co-glycolic acid)-b-poly(ethylene glycol)-b-poly(D,L-lactic acid-co-glycolic acid)] and different derivatives end-capped by small alkyl groups were synthesized, and the aqueous phase behaviors of these samples were studied. The virgin triblock copolymers and most of the derivatives exhibited a temperature-dependent reversible sol-gel transition in water. Both the poly(D,L-lactic acid-co-glycolic acid) length and end group were found to significantly tune the gel windows in the phase diagrams, but with different behaviors. The critical micelle concentrations were much lower than the associated critical gel concentrations, and an intact micellar structure remained after gelation. A combination of various measurement techniques confirmed that the sol-gel transition with an increase in the temperature was induced not simply via the self-assembly of amphiphilic polymer chains but also via the further hydrophobic aggregation of micelles resulting in a micelle network due to a large-scale self-assembly. The coarsening of the micelle network was further suggested to account for the transition from a transparent gel to an opaque gel.