新型规则有序多孔碳基复合定形相变材料的设计与储热构效关系研究

It is well known that there are problems like poor thermal conductivity for organic phase change materials(such as paraffins,fatty acids), although they can provide high latent heat and good thermal stablity. In order to overcome these problems, this project focuses on the study of a comprehensive modification and shape-stablization of organic phase change materials by using multi-disciplines intersection, and a novel multiporous carbon is creatively used as the surpporting material which possesses ordered multiprous structure. Firstly, spherical polystyrene is used as a template and the pre-polymer of melamine-formaldehyde reacts in the interface of spherical polystyrene. After the linking-polymerization, the product is roasted at high temperature, obtaining the multiporous carbon with ordered structure. Then,the organic phase change material is absorbed into the multiporous carbon by self-assembly of surfactant and the capillary absorption, resulting in the novel composite phase change material with high thermal conductivity and good thermal stability. Moreover, the melting/crystalline behavior and the latent heat of the organic phase change material inside the multiporous carbon will be investigated by means of phase diagram, nanotechnology, thermochemistry, spectroscopic characterization, theoretical calculations and other methods. The influence rules of the porous structure, pore size distribution and porosity of the multiporous carbon on the phase change temperature，heat transfer efficiency and the corresponding latent heat of the PCMs will be revealed.According to these rules, mathematical model will be established and the phase change mechanism and thermo-responsive rate will be described as well. It will provide a theoretical basis for industrial application of the composite shape-stablized phase change materials.

针对有机相变材料存在的导热系数低、固-液相变过程易流动泄露的缺陷，本项目从多学科交叉角度创造性地提出采用规则有序多孔结构的新型碳材料对其（如石蜡，脂肪酸）进行封装定形和系统改性研究：首先采用无皂乳液聚合法制得含羧基的单分散聚苯乙烯（PS）微球，再用种子模板乳液聚合法，以PS微球为模板，通过功能基团间的自组装，将三聚氰胺-甲醛预聚物交联聚合在PS微球表面和界面，然后高温焙烧炭化，得到具有规则有序介孔结构的多孔碳材料；最后通过表面活性剂的自组装及多孔碳材料的毛细吸附将有机相变材料封装入孔道结构中，制得高导热和热循环稳定性好的新型多孔碳基复合定形相变材料。运用相图、纳米技术、热化学、谱学表征等研究规则多孔结构内相变材料的结晶／熔融焓，揭示孔结构、孔隙率及孔径分布对相变材料的相变温度、热响应速率及相变焓的影响规律，建立数学模型，阐述其热传导机理和热响应速率，为复合相变材料的规模化应用提供理论依据。

本项目针对有机相变材料存在的导热系数低、固-液相变过程易流动泄露等缺陷，开展了一系列复合定形相变材料的创新性研究，并对相变材料在隔热防晒薄膜领域的智能控温效果进行了探索，取得的代表性成果如下：.（1）创新地提出采用苯乙烯小球为种子模板，通过功能基团的自组装，使三聚氰胺-甲醛预聚物在模板的表面及界面，高温炭化制备出规则多孔碳球，比表面积可达872.7 m2 g-1，孔径集中在2-5 nm和10-17 nm，具有较好的介孔结构，其与相变材料复合后的性能不佳，但700 oC碳化的样品比电容可达196.9 Fg-1，具有较高的可逆性。.（2）创造性地采用中性还原剂对氧化石墨烯进行诱导还原，制备了三维石墨烯，同时以正十八烷为相变材料，三维石墨烯为多孔支撑基体，制备了新型高性能的三维石墨烯基复合相变材料。研究发现，其相变潜热可达196.67 J/g，且提高了相变过程的热响应速率，经过60次冷热循环，相变温度和相变焓基本保持不变。同时，其导热系数可提高至1.636 W/(mk)。.（3）创造性地采用氧化石墨烯和MDI作为复合固固相变材料的硬段结构， PEG作为软段结构，通过功能基团间的自组装和接枝聚合，制得具有层状结构的新型石墨烯导热增强型复合固-固相变材料。该复合相变材料相变潜热可达156.7 J/g，GO在复合材料内部形成了连续的互穿网络结构，赋予复合材料较好的导热性能，使PEG具有较高的热相应速率，降低了熔融温度。复合材料经100次DSC热循环，相变潜热基本保持不变。.（4）为解决夏季建筑物、汽车等场所的隔热节能问题，创造性地将微胶囊相变材料、纳米二氧化钛与薄膜基体复合，通过固化成型，设计制备了新型相变控温隔热防晒复合薄膜。复合薄膜的相变潜热可达8.96 J/g，经过100次DSC热循环基本保持不变。薄膜能将屏蔽空间的温度控制在25-28 oC 持续 3298 s。复合薄膜具有较强的抗紫外线性能，在紫外光区的透过率小于10 %。