基于二元胶体剪切团聚构筑MXene/聚合物纳米复合材料及机理和性能调控

Homogeneous distribution of inorganic nanofillers in a polymer matrix, avoiding their agglomeration, has been a key scientific challenge in fabricating high-performance inorganic/organic polymeric nanocomposites. The available classic techniques such as solution mixing, in situ polymerization, melt blending, etc., often have the drawbacks of uncontrollable distribution of nanofillers or environmental pollution or highly complex manipulation. The proposed project aims to develop an efficient technique to generate nanocomposites based on intense shear-driven aggregation and gelation of binary colloids. The applied binary colloids are composed of two-dimensional MXene nanosheets and polymer particles. The intense shear is generated by forcing the binary colloids to pass through a microchannel system. We will tune the colloidal stability of the two components of the binary system such that the polymer particles, when passing through the microchannel, undergo the intense shear-driven aggregation, while the MXene nanosheets do not. Since the aggregation in the microchannel is extremely fast, the MXene nanosheets are quickly captured and homogeneously distributed inside the formed matrix of the polymer particles. The kinetics, aggregation and gelation behavior of the binary colloids induced by the intense shear force will be thoroughly investigated. The aggregation mechanism of the binary colloid will be understood, and the fractal morphology of the aggregates and gels will be clarified. Then, the proposed methodology is applied to generate nanocomposites. The relationship between the cluster, gel structures and properties of nanocomposites will be disclosed. Overall, this project not just has substantial contributions in developing new theory in colloidal stability and shear-driven aggregation of binary colloids, but also develops a simple, effective and massive technology for the preparation of inorganic/polymeric nanocomposites with the inorganic nanofillers homogeneously distributed in the polymer matrix.

控制无机纳米材料在聚合物基体中的均匀分布是构筑高性能无机/聚合物纳米复合材料的关键问题。针对溶液混合法、原位聚合法及熔融共混法等传统方法难以控制纳米填料的均匀分散性、不环保及操作复杂等缺点，本项目提出高效的二元胶体剪切共团聚法制备纳米复合材料。以MXene和聚合物胶体组成的二元胶体为研究对象，通过微通道系统产生的强剪切力调控胶体稳定性使聚合物颗粒在强剪切下团聚而MXene不团聚，由于在微通道中团聚极快，MXene被迅速捕捉而均匀分布于聚合物颗粒基体中。深入研究二元胶体在强剪切力下的共团聚和凝胶行为，探析团聚体大小、分形结构及动力学规律，揭示二元胶体共团聚机理。在此基础上构筑复合材料，阐明团聚体及凝胶结构对材料性能的影响规律。本项目既能丰富胶体稳定性及剪切团聚的科学基础理论，又能为制备无机/聚合物纳米复合材料领域探索出一种简单有效的、既能大规模应用又能保证纳米颗粒良好分散性的策略。

无机/聚合物纳米复合材料结合了无机纳米材料和有机聚合物各自独特的性能，同时呈现出优异的协同增强效应，被广泛地应用在导电材料、导热材料、高性能涂层以及阻燃材料等功能材料中。控制无机纳米材料在聚合物基体中的均匀分散以及与基体间强的界面相互作用是制备高性能多功能聚合物纳米复合材料的关键所在。针对传统制备方法难以控制纳米颗粒的均匀分散性、不环保及操作复杂等缺点，本项目提出了强剪切作用下的二元胶体复合法构筑纳米复合材料。项目以功能化MXene与聚合物胶体组成的二元胶体为研究对象，通过表面功能化调控MXene的化学性质及分散稳定性，研究了在强剪切作用下功能化MXene在聚合物胶体中的分散稳定性和团聚行为，在此基础上制备出系列高性能聚丙烯酸酯/MXene、环氧聚合物/MXene、聚氨酯/MXene纳米复合材料，阐明了纳米填料组成、表面特性、微观结构及其在基体中的分布状态与复合材料性能之间的内在联系和规律。该系列研究工作既能丰富胶体稳定性的科学基础理论，又能为高性能多功能无机/聚合物纳米复合材料的研发提供一种新策略。

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