蒙脱石聚合物纳米复合材料界面结构及力学性能分子动力学模拟研究

Montmorillonite (MMT)-based polymer nanocomposites have been widely utilized in various industries due to their many advantages. These materials are able to combine platelet building blocks with polymeric matrices to generate new materials both stiff and flaw-tolerant, especially the greatly reinforced mechanical properties, such as greatly increased tensile modulus. However, it remains important to effectively control the dispersion of nanofillers in the polymer matrix, and understand the contribution of clay-polymer interface to the properties of polymer nanocomposites. Due to the nanoscale nature of the interface and the unclear boundaries between interface and polymer matrix, it is extremely challenging to quantify their properties experimentally. Nonetheless, Molecular Dynamics (MD) simulation has become an effective method to determine the structure and properties of MMT-based polymer nanocomposites. However, unfortunately so far the use of theoretical and computational methods to study the properties of these materials has not been fully employed. This has so far restricted the full development and utilization of MMT-based polymer nanocomposites. The proposed research will continue to use MD simulations, together with rule-of-mixtures and experimental methods, to comprehensively analyze of factors affecting the overall mechanical properties of nanocomposites. The relationship of interface structure (effective interface thickness) and mechanical properties (Young's modulus, poisson ratio and shear modulus) of partially exfoliated nanocomposites will be quantified, and the overall mechanical properties of MMT polymer nanocomposites will be studied according to the morphologies of MMT characterized by TEM technique. Furthermore, the new strategies to reinforce the mechanical properties of MMT-based polymer nanocomposites will also be studied in this project. The completion of this project will provide better fundamental understanding of the nanocomposites manufacturing process and facilitate the development of novel technological innovations.

蒙脱石聚合物纳米复合材料将纳米填充材料的刚性、尺寸稳定性及热稳定性和聚合物主体的韧性、易加工性以及介电性能混合于一身，尤其具有优越的力学性能，如极强的拉伸模量等，成为近年发展迅速并得到广泛应用的材料。如何控制蒙脱石在聚合物主体中的有效分布，以及全面理解其结构尤其是界面结构对其整体性质的影响至关重要。由于纳米复合材料的纳米尺度特征，以及界面与聚合物主体的模糊边界条件，很难用实验手段对其量化表征。而分子动力学模拟成为研究分子尺度结构与性质的有效手段。目前针对这一材料的计算机模拟研究基础还相当薄弱，这在很大程度上制约了此材料的发展和应用。本申请在前期研究基础上，全面分析了影响纳米复合材料整体力学性能的因素。利用分子动力学模拟研究部分剥离型蒙脱石纳米复合材料界面有效厚度与力学性能如杨氏模量、泊松比和剪切模量等的关系，根据剥离型蒙脱石在聚合物主体中分散形貌和分布比例，使用混合率数学方法，准确预测纳米复合材料力学性能。本课题的研究成果将为制备具有更多优良性能的蒙脱石聚合物纳米复合材料提供重要的理论支撑。

蒙脱石聚合物纳米复合材料由于其优良的力学、热学、耐火性能、阻隔性能、介电性能等，是现今用于航空、航天、汽车等相关行业的先进材料。但制备性能优异的蒙脱石聚合物纳米复合材料极具挑战性。本项目开展计算机分子动力学模拟研究部分剥离型蒙脱石尼龙 6 纳米复合材料的界面结构及其力学性能，主要研究内容及取得的成果如下：.（1）.建立了部分剥离型蒙脱石尼龙 6 纳米复合材料分子动力学模型，并赋予了合适的粗粒化力场。建立了双片层及三片层“有效纳米粘土”作为纳米复合材料的基础材料，并分析了“有效纳米粘土”的压缩模量。.（2）.根据剥离型纳米复合材料各“有效纳米粘土”分布形态, 结合了“有效纳米粘土”压缩性能分子动力学模拟数据，运用了混合率数学方法，准确地预测了剥离型蒙脱石纳米复合材料整体压缩模量。.本课题在项目执行期间，共计在国内外期刊发表论文2篇，其中SCI收录1篇；EI收录1篇。形成技术总结报告一份，完成了国家自然科学基金申请书中规定的技术指标要求。本课题的研究成果将为制备具有更多优良性能的蒙脱石聚合物纳米复合材料提供重要的理论支撑。