Understanding the structure-property relationship of polymer-grafted nanosheets upon crumpling

Understanding the crumpling behavior of polymer-grafted nanosheet materials is of fundamental importance in engineering and technological applications. Here, we report the results of a systematic coarse-grained molecular dynamics (CG-MD) simulation study of the crumpling process of polymer-grafted graphene sheets at various polymer grafting density. We find that polymer grafted graphene sheets with larger grafting density exhibit more wrinkling in equilibrium than pristine graphene sheet and sheets with smaller grafting density. By evaluating the evolution of potential energy of the sheet during the crumpling process, our results show that the grafted polymer chains significantly reduce the adhesion properties of the graphene sheets. Notably, various structural properties of the crumpled polymer grafted graphene sheets, including the radius of gyration, hydrodynamic radius, and intrinsic viscosity, can be quantitatively described by a power-law scaling relationship about the radius of confining sphere during the crumpling process. Moreover, the shape descriptor analysis shows less self-folding and self-adhering upon crumpling for sheets with larger grafting density. In addition, the evaluation of stress distribution of the sheet further reveals the stress heterogeneity arising from grafted polymers and crumpling. Our findings highlight the critical role of grafted polymer in the crumpling process of graphene sheets, which has significant implications for the tailored design of crumpled polymer functionalized nanosheets.