Formation and Structural Characteristic of Perpendicularly Aligned Boron Nitride Nanosheet Bridges in Polymer/Boron Nitride Composite Film and Its Thermal Conductivity

The anisotropic alignment of boron nitride (BN) nanosheets was performed in polysiloxane/BN nanosheet composite film under a DC electric field with a change in polarity. The hexagonal BN nanosheets were dispersed by sonication in a prepolymer mixture of polysiloxane followed by highspeed mixing. The homogeneous suspension was cast onto a spacer of microscale thickness and applied to a high DC electric field while changing polarity before the mixture became cross-linked. Analysis revealed that linearly aligned BN nanosheet (LABN) bridges were fabricated in the composite film while connecting the film planes as bridges. This is for first report on the fabrication of linearly aligned nanosheet bridges inside organic-inorganic hybrid films. The fabricated LABN bridges were attributed to the enhancement in the thermal conductivity of the composite film, and the mechanisms underlying the formation of LABN bridges and heat conduction were discussed. (c) 2011 The Japan Society of Applied Physics