We demonstrated that the orientation of unmodified BN nanosheets an be controlled in a polymer matrix either perpendicular or parallel to the nanocomposite film surface with high anisotropy triggered by a rotating superconducting magnetic field (107) while the prepolymer suspension of polyepoxide was cross-linked. The resulting polymer nanocomposite had outstanding thermal anisotropy, and the increased thermal diffusivity was proportional to the anisotropic orientation of the BN nanosheet. This research provides a method to effectively control diamagnetic 1D or 2D nanofiller particles in polymer-based nanocomposites, and may provide enhanced dielectric thermal interface materials for the semiconductor industry. (C) 2013 Elsevier B.V. All rights reserved.