Toward highly compressible graphene aerogels of enhanced mechanical performance with polymer

Abstract

In this study, we developed a convenient way to prepare highly compressive durable graphene aerogels (GAs) with enhanced strength by combining the freeze-casting process with the binding effect of polymers. It was revealed that poly(acrylic acid) (PAA) or poly(ethylene oxide) (PEO) had no noticeable influences on the chemical reduction process of GO and the formation of the aerogel structure. However, they showed different effects on the mechanical performances of the resulting hybrid aerogels. When PAA was in the appropriate feeding content range (∼30 wt%), PAA could significantly improve the strength of GAs with a 200–300% increase and simultaneously preserve their elasticity. In contrast, PEO showed a weaker reinforcing effect, and the hybrid aerogels completely lost their elasticity when the PEO feeding ratio was greater than 20 wt%. Furthermore, hybrid aerogels had slightly reduced electrical conductivity compared with that of GA. After the thorough analysis of the microstructure of hybrid aerogels (e.g., WAXD, XPS, Raman), we proposed that PAA chains could bridge and bind the edges of different graphene layers together, thus strengthening the network structure of hybrid aerogels. The combination of a functional polymer (i.e., PAA) with the freeze-casting process to prepare more mechanically robust GAs is simple, and the process is scalable and economical.