Alignment-assisted high thermal conductivity and thermal anisotropy in poly(methyl methacrylate)/graphene nanolaminates

Understanding heat transport at the graphene-polymer (Gr-polymer) interface is the key to improve the thermal conductivity of Gr-based nanocomposites. Here, we fabricate poly (methyl methacrylate)/graphene (PMMA/Gr) nanolaminates and find an ultrahigh increase of the in-plane thermal conductivity (8.9 ± 0.9 Wm−1K−1) compared to net PMMA and the thermal conductivity anisotropy (approximately equal to 53) at low Gr loading (1 vol. %). The strong anisotropic thermal conduction can be attributed to the predominantly in-plane oriented Gr nanoflake and, intriguingly, the graphene-induced planar alignment of PMMA in the proximity of Gr, as revealed by polarized infrared spectroscopic (-IR) imaging, nano-FTIR and IR s-SNOM. We demonstrated the contribution of interface-induced confinement to the observed thermal property, providing deeper insights into heat transport at the Gr-polymer interface.