Green Approach Toward In Situ Exfoliation and Enhanced Compatibility To Obtain Highly Conductive Polypropylene/ Graphene Composites

The high-interfacial tension, poor compatibility, low dispersion, and toxic auxiliaries remain a historical challenge in fabricating polymer/graphene functional composites. Herein, an industrially viable and green process of manufacturing poly-propylene/few-layer graphene (PP/FLG) composites with en-hanced interfacial adhesion was demonstrated by combining planetary ball milling and supercritical CO2 (scCO2). Thus, a PP/FLG composite was obtained in one step without requiring organic solvents and toxic auxiliaries. The PP/FLG composite showed an appreciably enhanced through-plane thermal con-ductivity and in-plane thermal conductivity up to 6.15 and 4.75 W & BULL; m-1 K-1, respectively, at an FLG loading of 15 wt %. Also, the in -plane electrical conductivity (IP-sigma) and through-plane electrical conductivity (TP-sigma) increased to 4.6 x 10-2 and 2.8 x 10-2 S & BULL;m-1, respectively, at 3 wt %. Furthermore, the mechanical performance of the composite also improved. Such significant improvements were attributed to the mechanochemical and plasticizing effects of ball milling and scCO2, respectively, which improved the interfacial compatibility between graphene and the polymer matrix. Also, scCO2 exploited complete exfoliation of bulk graphite into few-layer (& LE;10) graphene flakes, making continuous randomly oriented and interconnected graphene in the matrix. This process holds great potential to prepare functional polymer-graphene composites for next-generation electronic devices and scale-up opportunities.

Automated summary

A poly-propylene/few-layer graphene (PP/FLG) composite with enhanced interfacial adhesion was successfully fabricated using a combination of planetary ball milling and supercritical CO2 (scCO2). The composite exhibited significantly improved thermal and electrical conductivity as well as mechanical performance. The successful fabrication process holds great potential for the development of functional polymer-graphene composites for next-generation electronic devices.