Phase change behaviors of PEG on modified graphene oxide mediated by surface functional groups

This paper carries out an extensive study on the phase change behavior of polyethylene glycol (PEG) on modified graphene oxide (GO). Distinct phase change behaviors are observed on GO, reduced GO (rGO) and carboxylic functionalized GO (GO-COOH) composites, which is attributed to the different surface functional groups on GO sheets. Notably, the introduction of supporting materials results in lower melting point of PEG, in the order of GO-COOH < GO < rGO at the same PEG content. The crystallization fraction of PEG follows the same trend. A significant depression in melting point of 16.8 degrees C is observed for the PEG/GO-COOH composite with 80 wt% PEG. The correlation between the phase change behaviors and the surface functional groups is discussed. The study suggests that the phase change behaviors in shape-stabilized phase change materials can be mediated by surface modification with different functional groups. (C) 2015 Elsevier Ltd. All rights reserved.