Polyepoxide-based nanohybrid films with self-assembled linear assemblies of nanodiamonds

Self-assemblies of nanodiamonds (NDs) were incorporated into polyepoxide-based composite films by electric field inducement. ND particles were dispersed by sonication in a prepolymer mixture of polyepoxide followed by high-speed mixing. The homogeneous suspension was cast onto a polyamide spacer and subjected to three different electric fields, AC, DC and switching DC, before the mixture became cross-linked. Analysis revealed that linearly aligned NDs (LANDs) were fabricated in the hybrid film, and the LANDs were aligned perpendicular to the film surface with high anisotropy. The nanohybrid films with assemblies of LANDs exhibited enhanced thermal conductivity with minimal decrease in the electrical insulation properties of the polyepoxide and are therefore attractive for application as thermal interface materials in the semiconductor industry. Mechanisms for the field-induced fabrication and structural variation of LANDs in the polymer matrix are elucidated in relation to enhancement of the physical properties. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.