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Thermally insulating composite aerogel with both active absorption and passive insulation functions based on azobenzene-modified chitosan/oligomeric β-cyclodextrin

Update time: 01/22/2022
Active heat absorption strategy and passive heat insulation strategy often go their separate way, and each has its own advantages and disadvantages. This study explores a new thermal insulation material design strategy that introduces thermo-sensitive host-guest inclusion complexes as active heat-absorbing components in passive thermal insulation aerogel. According to this strategy, a novel azobenzene-modified chitosan/oligomeric beta-cyclodextrin (CSAZO/CD) composite aerogels were prepared by the freeze-drying method. It was found that CSAZO/CD composite aerogels showed tunable porous structure, good mechanical properties and more impor-tantly wonderful thermal insulation properties. Since CSAZO/CD aerogels contained not only porous structure (porosity 91.03%-95.85%), but also Azo-beta CD complexes in the matrix as active heat-absorbing components, these materials showed better thermal insulation capability than other aerogels with similar thermal conduc-tivity. And unlike classic porous material-supported phase change materials which suffer the leakage of PCM after multiple thermal cycles, CSAZO/CD composite aerogels show good long-term stability since the Azo-beta CD complexes absorb heat by the solid-to-solid transition. Furthermore, CSAZO/CD composite aerogels showed even better thermal insulation behavior under UV irradiation. The unique insulation properties of CSAZO/CD aerogels make them good candidates for thermal insulation materials in many fields, such as ultra-thin thermal insulation in high temperature or UV environment.