Preparation and application of recyclable polymer aerogels from styrene-maleic anhydride alternating copolymers

This paper reports a novel polymer aerogel that can be repeatedly regenerated by ammonia water at 95 degrees C. Styrene-maleic anhydride alternating copolymer (SMA) has been synthesised and converted into a water-soluble copolymer (SMAN) containing ammonium maleate groups. After freeze drying and heat treatment, a super-oleophilic and hydrophobic polymer (SMI) aerogel is obtained, which has very high heat resistance and excellent thermal insulation property. The glass transition temperature and initial decomposition temperature can reach 247 degrees C and 307.6 degrees C, respectively. In addition, SMI aerogels also possess aggregation-induced emission (AIE) properties. It is especially worth highlighting its excellent recyclability as almost 100 % of the aerogel can be converted back to SMAN solution that can be used again for SMI aerogel preparation. Furthermore, SMI aerogel can be upcycled as the performance of the regenerated aerogel is not reduced but improved compared with the original aerogel. Two recyclable phase-change composites have been also prepared by absorbing phase-change materials (PCMs) into SMI aerogels. One is for cold-storage (PCCC) with real-time temperature monitoring function composed of SMI aerogel and dodecane. 9.8 g PCCC could keep 10 mL ethanol below 0 degrees C for more than 2 h. The other is for heat-storage (PCCH) with photothermal conversion function composed of SMI aerogel, paraffin and reduced graphene oxide. PCCH could be heated to 70 degrees C within 30 min under 100 mW/cm2 sunlight irradiation. Both PCCC and PCCH can be separated into two layers in ammonia water: the PCMs on top and SMAN on bottom; therefore, the composites can also be recycled easily and regenerated easily after being discarded.