Study of the porous structure of transparent-superinsulating polyurethane aerogels through X-ray nanoholotomography: the key basis for predi

Transparent polyurethane aerogels were synthesized for the very first time in our previous publications. These materials present the lowest thermal conductivity ever measured for this aerogel matrix, according to the literature. To understand and further improve this value it is essential to theoretically model their thermal conductivity. Their porous structure, composed by a pearl-necklace structure with 30 nm-particles and presenting a bimodal porosity (pores below 100 nm) is the main responsible for their great insulating capacity, therefore, providing an accurate model relies on characterizing this inner structure. Thus, the use of the ESRF facilities (synchrotron radiation-based phase-contrast hard X-ray nanoholotomography under cryogenic conditions) would be really useful for this investigation. It will allow to determine for the first time the porous structure of transparent PU aerogels, information of critical importance for the state of the art and predicting their properties.

本团队此前的研究工作首次合成了透明聚氨酯气凝胶（polyurethane aerogels）。据现有文献报道，这类材料的导热系数为该类气凝胶基体中实测到的最低值。为深入理解该导热系数并进一步优化其性能，对其开展理论建模是必不可少的环节。该材料的多孔结构由粒径30纳米的珍珠链状结构构成，且呈现双峰孔隙分布（孔径小于100纳米），这是其具备优异隔热性能的核心原因；因此，要建立精准的理论模型，必须先完成对其内部结构的表征。为此，采用欧洲同步辐射光源（European Synchrotron Radiation Facility, ESRF）的实验装置——即低温环境下基于同步辐射的相衬硬X射线纳米全息层析成像技术——将为本次研究提供关键技术支撑。该技术将首次实现透明聚氨酯气凝胶多孔结构的精准表征，这一信息对于当前领域的研究前沿以及预测材料性能均具有至关重要的意义。