摘要
High performance thermal insulation materials are urgently demanded for energy saving and thermal protection applications.Organic aerogels are considered as promising and highly efficient thermal insulation materials,but high shrinkage has been a major obstacle to limit their development and application.Herein,by a co-polymerization of formaldehyde(F)and benzoxazine prepolymers,polybenzoxazine with increased crosslink density and thus enhanced gel strength was formed,leading to low shrinkage polybenzoxazine(PBOF)aerogels with hierarchical micro/nanostructures.The hierarchical porous nanoskeleton of PBOF aerogels,composed of stacked thick-united spherical nanoparticles,was formed due to the different solubility of the reactants in N,N-dimethylformamide and F aqueous solution.Benefitting from the low shrinkage(13.22%,exceeding 60%reduction),the PBOF aerogels exhibit a low thermal conductivity of 0.0397 W m^(−1)K^(−1)at room temperature and outstanding thermal protection ability at high temperature.A 13 mm thick sample could resist a butane flame of 1300°C for 90 s,and the hand was not burn when touching the back.This strategy enables PBOF aerogels with a new perspective for their applications in civil and military fields.
高性能隔热材料是节约能源和热防护应用迫切需要的.有机气凝胶被认为是前景广阔的高效隔热材料,但是高收缩率一直是限制其发展和应用的主要障碍.本文通过甲醛(F)和苯并嗪预聚物的共聚,形成了交联密度增加从而凝胶强度增强的聚苯并嗪凝胶,进而得到了具有多级微/纳结构的低收缩率聚苯并嗪(PBOF)气凝胶.由于反应物在N,N-二甲基甲酰胺和F水溶液中的溶解度不同,PBOF气凝胶的分层多孔纳米骨架由厚连接球形纳米颗粒堆叠而成.得益于低收缩率(13.22%,降低超过60%),PBOF气凝胶具有0.0397 W m^(−1)K^(−1)的热导率,在高温下具有出色的热防护能力.13 mm厚的样品可在1300°C的丁烷火焰中抵抗90 s,手接触其背面也不会被灼伤.这种策略为聚苯并嗪气凝胶在民用和军用领域的应用提供了新的视角.
基金
supported by the National Key Research and Development Program of China(2022YFC2204403)
the Key Research and Development Plan of Hunan(2022GK2027)
the Natural Science Foundation of Hunan(2023JJ30632).
