限域网络结构特征及其复合相变材料热物理性能的构效关系

The development of efficient and economic strategy addressing thermal energy storage or release issues should be of great importance for matching availability and demand with respect to time and also with respect to space. However, the phase transition behavior and crystallization characteristics of phase change materials under the confined space is still a scientific problems. Accordingly, we proposed for designing a series of composite phase change materials using paraffin wax, fatty acids and polyols as phage change material and three-dimensional network as defined matrix, which formed though the chemical reaction between the connective molecules and functional group on the surface of modified attapulgite. And then, the effect of connected molecule’s size on the morphology, pore structure and specific surface area of the network and the matrix structure on the thermal storage capacities, phase change properties, stabilities, reliability and environmental risk under a long period of usage of the composite will be investigated. Also, the relationship of thermal storage performance and the structure of the as-synthesized matrix, the mechanism of phase transition will be clarified at the molecular level. The proposed project will not only possibly develop novel, high performance phase change materials with great potentials for practical use in the field of spacecraft thermal controlling and solar energy utilization, provide a new way for high value-added using of attapulgite, but also provide basic experimental results and scientific evidence for further design, preparation of composite phase change materials with good performance.

受限环境及界面耦合条件下相变材料的相变行为及结晶特性是相变储热领域函待解决的科学问题。项目拟通过键合分子与改性凹凸棒棒晶表面基团间的化学反应，构筑系列以共价键键合的凹凸棒棒晶刚性骨架为可控限域网络，以石蜡、脂肪酸、多元醇等有机物为相变物质的限域复合相变材料，进而通过键合分子尺寸、刚性、基团和官能团的选择与设计，调控限域网络的结构特征及其复合相变材料的储热能力与相变行为，系统地研究限域网络结构特征对复合相变材料相变潜热、相变行为、稳定性和结晶特性的影响规律，探索限域及界面耦合条件下复合材料相变潜热、相变温度变化的微观机制，获得其结晶机理及结晶动力学，构建限域网络结构特征与复合相变材料性能间的结构-性能关系。项目旨在丰富受限及界面耦合环境下相变材料构效关系的科学内涵，为进一步设计低品位热源相变储热材料提供理论依据，为凹凸棒石的高值化利用开辟新途径。

为明晰限域网络结构及界面耦合作用对复合相变材料储热能力、相变行为和结晶过程的影响规律，进而构建限域复合相变材料的结构-性能关系，项目采用“grafting-from”法、“grafting-onto”法和水热自组装法构筑了系列凹凸棒石三维限域网络，组装了系列限域复合相变材料，研究了限域网络结构特征对复合相变材料热物理性能的影响及其结构-性能关系。结果表明：三维限域载体的孔径可通过键合分子尺寸而调控。基于三维载体的限域复合相变材料储热能力、相变温度与载体的孔径呈明显的线性关系，即限域复合相变材料储热能力、相变温度随载体孔径的减小而减小，但其与载体的比表面积、孔体积和孔道结构无明显相关性。当限域载体孔径较小时，限域载体孔道内出现“非结晶层”和“冷结晶”的现象。当载体表面和相变物质间相容性良好时，有利于相变物质进入“非凝固层”，减弱“非凝固层”的形成，并使复合相变材料的储热能力得以提升。提高三维限域网络的互通性和主-客体间的偶合行为，有利于界面热阻的降低；限域、包封提供的异质成核位点可抑制相变材料的过冷度，但增稠剂对过冷度的缓解具有针对性。孔径可调控凹凸棒石三维载体的成功构筑，为拓展凹凸棒石的应用领域提供了新思路，获得的限域网络结构特征与复合相变材料性能间的结构-性能关系，为进一步设计低品位热源相变储热材料提供了理论依据。