Enhancing thermal conductivity of PMMA/PS blend via forming affluent and continuous conductive pathways of graphene layers

Abstract Poly (methyl methacrylate)/polystyrene (PMMA/PS; 60/40 w/w)/reduced graphene oxide (rGO) blend nanocomposites are prepared via injecting GO suspension into the melt during extrusion, an industrially relevant process. The synergistic effect of the injected water and screw shear simultaneously promotes the exfoliation, dispersion, and in situ reduction of the GO, and locates rGO layers in the PS phase and at the phase interfaces. The rGO layers at the interfaces effectively improve the compatibility between the PMMA and PS phases and stabilize the obviously finer co-continuous structure via forming the hydrogen bond and π-π stacking. The nanocomposite samples prepared with water injection exhibit 30–90% increments in thermal conductivities compared to the corresponding samples without water injection. The nanocomposite sample with only 0.8 wt% GO exhibits a thermal conductivity of 0.74 W/mK (3.62 times higher than the corresponding blend sample), and can effectively reduce the surface temperature of an LED lamp when used as its thermal interface material. The enhanced thermal conductivities in the nanocomposites prepared with injected water result from the formation of more numbers of affluent and continuous thermal conductive pathways of the rGO layers.