Enhanced Thermal Diffusivity by Vertical Double Percolation Structures in Polyimide Blend Films Containing Silver Nano particles

The thermal diffusivity along the out-of-plane direction (D-perpendicular to) in polyimide (PI) blend films containing silver nano particles (Ag-NPs) was investigated. PI blend films composed of a sulfur-and a fluorine-containing PI were prepared via spin-coating and thermal curing of the precursor solutions dissolving silver nitrate. Microphase-separated structures with a vertical double percolation (VDP)'' morphology were spontaneously formed in the films, in which two phases are separately aligned along the out-of-plane direction, and Ag-NPs were preferentially precipitated in the sulfur-containing PI phase. The blend films exhibited higher D-perpendicular to values than monophase PI films containing homogeneously dispersed Ag-NPs. These results indicate that the VDP structure functions as an effective thermal conductive pathway.