Enhancing through-plane thermal conductivity of fluoropolymer composite by developing in situ nano-urethane linkage at graphene- graphene interface

Attributed to the intense development and complexity in electronic devices, energy dissipation is becoming more essential nowadays. The carbonaceous materials particularly graphene (Gr)-based thermal interface materials (TIMs) are exceptional in heat management. However, because of the anisotropic behavior of Gr in composites, the TIMs having outstanding through-plane thermal conductivity (^┴TC) are needed to fulfill the upcoming innovation in numerous devices. In order to achieve this, herein, nano-urethane linkage-based modified Gr and carbon fibers architecture termed as nanourethane linkage (NUL)-Gr/carbon fibers (CFs) is fabricated. Wherein, toluene diisocyanate is utilized to develop a novel but simple NUL to shape a new interface between graphene sheets. Interestingly, the prepared composite of NUL-Gr/CFs with polyvinylidene fluoride matrix shows outstanding performance in heat management. Owing to the unique structure of NUL-Gr/CFs, an unprecedented value of ^┴TC (~ 7.96 W·m^-1·K^-1) is achieved at a low filler fraction of 13.8 wt.% which translates into an improvement of ~ 3,980% of pristine polymer. The achieved outcomes elucidate the significance of the covalent interaction between graphene sheets as well as strong bonding among graphene and matrix in the composites and manifest the potential of proposed NUL-Gr/CFs architecture for practical applications.