冰模板法制备长程有序多孔材料

发布时间：2018-08-07 10:36

【摘要】：定向冰冻法作为一种制备取向性多孔材料的方法,由于其具有快速、可规模化、环境友好的特点而得到越来越广泛的关注。这种以取向性的冰晶作为模板的反应机制可以应用于多种材料体系,包括冰冻凝胶、陶瓷、聚合物及其复合材料。本文提出了一种定向冰冻过程孔径调控的新机制。采用浸润性不同的固体作为冰冻表面,合成了具有取向性多孔结构的聚乙二醇水凝胶。研究发现,随着浸润性增强,孔径减小,根据孔径和接触角数值拟合出其间的关系式,可用来预测不同浸润性冰冻表面得到的凝胶孔径大小。用液氮作为冷源,亲水性聚乙烯醇修饰过的铜片作为冰冻表面得到了孔径小于2μm的微管状结构,比用传统定向冰冻法制备的多孔材料孔径降低了一个数量级,大大扩展其在分离催化领域的应用前景。在此基础上,通过冰冻表面的区域化浸润性修饰,也实现了孔径的区域化调控。通过双向冰冻法制备了一种新型的仿生石墨烯气凝胶,具有长程有序的带连接的片层结构,使得其同时具有高强度和高回复性。系统研究了气凝胶的结构调控因素,得到了最佳的实验条件,并且提出了基于粘度变化的结构相图。在此基础上,对比了仿生结构和常规结构的形貌和性能差异,进一步研究了其结构特征:层数和连接数目对机械性能的影响,得到了优化的结果。压缩-电学性能也凸显了其在柔性电子领域的应用潜能。同时,本研究也为通过仿生概念,实现多孔材料结构的可控制备,进而提高其机械性能和功能提供了思路。
[Abstract]:As a method of preparing oriented porous materials, directional freezing method has attracted more and more attention due to its rapid, scalable and environment-friendly characteristics. The mechanism of using oriented ice crystals as template can be applied to many material systems, including frozen gels, ceramics, polymers and their composites. In this paper, a new mechanism of aperture control in directional freezing process is proposed. Polyethylene glycol hydrogels with oriented porous structure were synthesized by using different soakage solids as frozen surfaces. It is found that the pore size decreases with the increase of wettability. The relationship between pore size and contact angle can be used to predict the size of gel pore size obtained from different infiltrating frozen surfaces. Using liquid nitrogen as cold source and hydrophilic polyvinyl alcohol modified copper as freezing surface, microtubules with pore diameter less than 2 渭 m were obtained, which was one order of magnitude lower than that of porous materials prepared by traditional directional freezing method. Its application prospect in the field of separation catalysis is greatly expanded. On this basis, the regionalization of pore size is also realized through the regional wettability modification of frozen surface. A novel bionic graphene aerogel was prepared by bidirectional freezing method. The bionic graphene aerogel has a long and ordered lamellar structure with high strength and high recoverability. The structure control factors of aerogels were studied systematically and the optimum experimental conditions were obtained. The structure phase diagram based on viscosity change was proposed. On this basis, the morphologies and properties of the bionic structure and the conventional structure are compared, and the effects of the number of layers and the number of connections on the mechanical properties are further studied, and the optimized results are obtained. Compression-electrical properties also highlight its potential applications in flexible electronics. At the same time, this study also provides a way to realize the controllable preparation of porous material structure and improve its mechanical properties and functions through the bionic concept.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ427.26;TB383.4

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