Multi-scale simulation of stress transfer across ‘polymer bridge’ in graphene oxide/halloysite organic-inorganic hybrid aerogel

Abstract

In our previous work, organic-inorganic hybrid aerogels were successfully constructed utilizing graphene oxide (GO) sheets and halloysite nanotubes (HNTs), and interesting stress transfer behavior were found. Through preliminary experimental studies, we found that the movement of polymer molecules significantly affected the stress transfer behavior of aerogels. The mechanism might involve macroscopic and microscopic scales, which were difficult to be adequately studied by conventional experimental means. Therefore, this paper investigated the stress transfer behavior of hybrid aerogels utilizing finite element analysis (FEA) combined with molecular dynamics (MD) multi-scale simulation methods. The influence of the connection angles of GO and HNTs on the stress transfer ability was studied utilizing the FEA combined with theoretical formulas. The GO polymer pull-out systems were established by MD. The pull-out processes of polymethylmethacrylate (PMMA) and polysiloxane (PSO) were compared. The effect of oxygen-containing functional group coverage of GO on interface strength was studied. The results indicated that connection angles of 60° and 30° contributed more to the stress transfer between GO and HNTs under tensile and compression stress, respectively. The interfacial enhancement effect of the GO/polymer systems reached saturation when the coverage of oxygen-containing functional groups on the GO surface was 20 %. Si–O–Si agglomeration networks were formed by silane-modified GO and PSO, which possessed stronger interfacial strength.