Efficient mechanochemical treatment for multifunctional polycarbonate/CNT nanocomposites

Mechanochemical treatment offers a sustainable approach for the development of polymer nanocomposites by activating and dispersing nanofillers in polymers through mechanical energy rather than chemical reagents. It can improve interfacial contact, minimise filler damage and support scalable processing of multifunctional composites. In this work, two mechanochemical strategies, i.e. conventional impact-driven ball milling and a shear-dominated kitchen blender process conducted in deionised water, were developed to address the entanglement and agglomeration of multi-walled carbon nanotubes (MWCNTs) in a polycarbonate (PC) matrix. Both strategies disentangled CNT bundles to certain extents; neither ball milling nor kitchen blender treatment caused measurable changes in the molecular weight of PC. During treatment, PC particles were introduced, enabling the disentangled CNTs to coat the particle surface. This configuration not only suppressed the re-agglomeration of CNTs during drying but also effectively promoted stable dispersion during subsequent melt compounding. In comparison with ball milling, the kitchen-blender treatment efficiently generated a higher degree of shear, turbulence and cavitation-assisted micro-jets, which more effectively separated compact CNT bundles while minimising defect generation. Prepared by an industrial method, the resulting PC/CNT nanocomposites exhibited outstanding multifunctional properties, e.g. a 35% increase in tensile strength to 88.6 MPa, a 77% increment in thermal conductivity, a reduction in resistivity of more than ten orders of magnitude and an electromagnetic interference shielding effectiveness of up to 24.2 dB at 20 wt% of CNTs. This work demonstrates that high-shear mechanochemical treatment provides an efficiently, scalable and environmentally favourable route for producing high-performance PC/CNT nanocomposites.