聚酰亚胺气凝胶材料的制备及其应用

Preparation and application of polyimide aerogel materials

聚酰亚胺(polyimide,PI)由于具有较好的力学性能、优异的耐化学性、良好的介电性能和高温稳定性,被认为是一种应用前景广泛的高温工程聚合物.聚酰亚胺的各类制品如薄膜、涂料、胶黏剂、光电材料、先进复合材料、微电子器件、分离膜以及光刻胶等已经被广泛应用于电子信息、防火防弹、航空航天、气液分离以及光电液晶等领域.聚酰亚胺气凝胶(PIA)是由聚合物分子链构成的相互交联的三维多孔材料,结合了聚酰亚胺和气凝胶的优异性能,使其不但具有聚酰亚胺的优异特性,而且具有气凝胶的轻质超低密度、高比表面积、低导热系数以及低介电常数等突出特点,因此聚酰亚胺气凝胶材料迅速发展成为性能优异的有机气凝胶之一,并且在航空航天、电子通讯、隔热阻燃、隔音吸声以及吸附清洁等领域展示出广阔的应用前景.鉴于该材料的这些特质,本文对聚酰亚胺气凝胶的制备方法、影响因素(溶剂效应、单体结构和固含量)以及应用进行了论述,并对聚酰亚胺气凝胶材料的未来发展进行了展望.

Polyimide(PI)is a polymer with the imide ring on the major chain.Due to the stable structure of the rigid aromatic ring and conjugation effect of the aromatic heterocyclic ring of the imide ring,its bond energy of the main chain and intermolecular interaction are strengthened.Therefore,it has good mechanical properties,excellent chemical resistance,good dielectric properties and high temperature stability,with applicability as a high temperature engineering polymer with broad application potential.PI products,such as films,coatings,adhesives,photoelectric materials,advanced composite materials,microelectronic devices,separation films and photoresist,have been widely used in electronic information,fire and bulletproofing,aerospace,gas-liquid separation,photoelectric liquid crystals and other fields.Polyimide aerogels(PIA)are cross-linked,three dimensional porous materials made up of polymer molecular chains,combining the excellent properties of PI and aerogels,such as lightweight,low density,high specific surface area,low coefficient of thermal conductivity and a low dielectric constant.Therefore,PIA are being rapidly investigated as an excellent organic aerogel for broad application in aerospace,electronic communications,heat insulations,flame retardants,sound absorption,adsorption cleaning and other fields.Since National Aeronautics and Space Administration(NASA)and other scientific research institutions have developed flexible PIA materials and successfully used them in military and civilian applications,sophisticated weapons,Mars exploration and other application fields,their application research and development has been expanded.Given the characteristics of the PIA materials and the need to improve the preparation process and properties,the preparation method,influencing factors(solvent effect,monomer structure and solid content),application and future development are discussed in this paper.