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

The thermal diffusivity along the out‐of‐plane direction ( D ⟂ ) in polyimide (PI) blend films containing silver nanoparticles (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. Micro‐phase‐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 ⟂ values than monophase PI films containing homogeneously dispersed Ag‐NPs. These results indicate that the VDP structure functions as an effective thermal conductive pathway. magnified image