液晶嵌段共聚物接枝氧化石墨烯的合成及其纳米复合物的自组装行为与热响应性质研究

For the self-assembly of the 2D nanosheets/block copolymers (BCPs) nanocomposites, the distribution of 2D nanosheets can be guided by the microdomain structures of the BCPs, and in reverse, the 2D nanosheets with high aspect ratios can influence the self-assembly behaviors and the properties of the BCPs. However, the conventional clay nanosheets are difficult to be uniformly distributed within the block copolymers, and the common coiled block copolymers lack the ability to form hierarchical nanostructures and lack the responses to stimuli. The aim of this study is to synthesize a new kind of nanocomposite through graft-to method using graphene oxide (GO) as 2D nanosheet and a liquid crystalline block copolymer as BCP which can form hierarchical nanostructures in bulk and can form thermoreversible organogel in solution, and to investigate the self-assembly behaviors as well as the thermoresponsive poperties of the corresponding nanocomposites. On one hand, the self-assembly behavior of the nanocomposite in bulk will be studied including the arrangement of the 2D GO sheets and the influence of the 2D GO sheets on the morphologies of the block copolymers as well as the thermoresponsive properties of the nanocomposite. On the other hand, the gelation behaviors of the nanocomposites in solution will be studied, and the influence of the GO sheets on the gelation behavior and the mechanical properties of the gel will be investigated. Consequently, this work will open an avenue to the realization of a new kind of 2D nanosheets/block copolymers nanocomposite and provide the scientific evidence of the relationship between the hierarchical nanostructures and thermal responsiveness as well as mechanical properties of the nanocomposite.

二维纳米片层/嵌段共聚物纳米复合物的自组装中嵌段共聚物的相分离结构对纳米片层具有诱导排列作用，同时纳米片层对嵌段共聚物的自组装行为及性能也能起到调控作用。但粘土纳米片层存在难以均一分散，且普通柔性嵌段共聚物存在自组装结构尺度单一及缺乏刺激响应的缺点。本课题拟以易修饰及易分散的氧化石墨烯作为纳米片层，与在本体中能形成多级自组装结构且在溶液中具有凝胶作用的液晶嵌段共聚物通过可控接枝反应得到液晶嵌段共聚物接枝的氧化石墨烯，并研究接枝物及其与相应嵌段共聚物的纳米复合物的自组装行为及热响应性。在本体自组装中考察氧化石墨烯片层排列与嵌段共聚物多级自组装形貌之间的相互影响及温度变化导致其自组装结构转变带来的热响应性。在溶液自组装中考察氧化石墨烯对凝胶条件和凝胶力学性能的影响及其热响应性。本项目的研究将为新型二维纳米片层/嵌段共聚物纳米复合物的多级自组装结构与其热响应性及力学性能之间的关系提供科学依据。

本项目研究基于对二维纳米片层氧化石墨烯进行功能化修饰改性，利用聚合物共价修饰的石墨烯制备聚多肽及其嵌段共聚物纳米复合物材料，并研究其自组装行为。复合材料自组装中嵌段共聚物的相分离结构能够对纳米片层的排列起到诱导作用，同时纳米片层对嵌段共聚物的自组装行为及性能也能起到调控作用。在项目的研究中，我们分别成功合成了聚谷氨酸卞酯和聚二甲基硅氧烷共价接枝的石墨烯材料以及聚谷氨酸卞酯与聚二甲基硅氧烷形成的嵌段共聚物材料。所合成的聚合物接枝石墨烯能够良好的分散于有机溶剂中。并制备了具有不同亲疏水性的石墨烯薄膜材料。所合成的聚多肽及其嵌段共聚物具有热刺激响应性自组装凝胶化能力，研究了其自组装分子排列机理。通过溶液共混法成功制备了石墨功能化的复合凝胶，研究了复合凝胶的微观形貌与自组装性能。并通过力学性能测试表明少量功能化修饰石墨烯的加入有利于大大提高凝胶的机械性能。从而实现了具有多级微观形貌并具有热响应性的新型二维纳米片层/嵌段共聚物纳米复合材料以及复合有机凝胶的研究。完成了项目的预期研究设想。

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