Alignment-assisted high thermal conductivity and thermal anisotropy in poly(methyl methacrylate)/graphene nanolaminates
Bohai Liu, Christos Pavlou, Meguya Ryu, Ayumi Ishihara, Jizhu Hu, Costas Galiotis, Junko Morikawa, Xiangfan Xu, George Fytas
Abstract
Understanding heat transport at the graphene-polymer ( <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mi>Gr</a:mi> </a:math> -polymer) interface is the key to improve the thermal conductivity of <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:mi>Gr</c:mi> </c:math> -based nanocomposites. Here, we fabricate poly (methyl methacrylate)/graphene (PMMA/ <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"> <e:mi>Gr</e:mi> </e:math> ) nanolaminates and find an ultrahigh increase of the in-plane thermal conductivity (8.9 ± 0.9 W <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"> <g:msup> <g:mrow> <g:mrow> <g:mi mathvariant="normal">m</g:mi> </g:mrow> </g:mrow> <g:mrow> <g:mo>−</g:mo> <g:mn>1</g:mn> </g:mrow> </g:msup> <g:msup> <g:mrow> <g:mrow> <g:mi mathvariant="normal">K</g:mi> </g:mrow> </g:mrow> <g:mrow> <g:mo>−</g:mo> <g:mn>1</g:mn> </g:mrow> </g:msup> </g:math> ) compared to net PMMA and the thermal conductivity anisotropy (approximately equal to 53) at low <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"> <k:mi>Gr</k:mi> </k:math> loading (1 vol. %). The strong anisotropic thermal conduction can be attributed to the predominantly in-plane oriented <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"> <m:mi>Gr</m:mi> </m:math> nanoflake and, intriguingly, the graphene-induced planar alignment of PMMA in the proximity of <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"> <o:mi>Gr</o:mi> </o:math> , 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 <q:math xmlns:q="http://www.w3.org/1998/Math/MathML" display="inline"> <q:mi>Gr</q:mi> </q:math> -polymer interface.