The mesoscopic simulation technique was applied to describe the phase separation behavior of polyimide blends and used for design of immiscible polyimide/BN blend films with enhanced thermal conductivity. The simulation equilibrium morphologies of different poly(amic acid)(PAA) blend systems were investigated and compared with optical images of corresponding polyimide blend films obtained by experiment. The immiscible polyimide blend films containing nano-/micro-sized BN with vertical double percolation structure were prepared. The result indicated that the thermal conductivity of polyimide blend film with 25 wt% nano-sized BN reached1.16 W/(m·K), which was 236% increment compared with that of the homogenous film containing the same BN ratio. The significant enhancement in thermal conductivity was attributed to the good phase separation of polyimide matrix, which made the inorganic fillers selectively localized in one continuous phase with high packing density, consequently, forming the effective thermal conductive pathway.
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