PH triggered hydrogen bonding for preparing mechanically strong, electromagnetic interference shielding and thermally conductive waterborne polymer/graphene@polydopamine composites

Abstract

Flexible and highly filled conductive polymer composites with strong mechanical properties are highly desirable as electromagnetic interference (EMI) shielding and thermally conductive materials for human protection and wearable devices. Herein, a tough interface has been built up by the combination of polydopamine modification and pH triggered hydrogen bonding to prepare flexible and mechanically robust waterborne polyacrylate/graphene@polydopamine composites. Graphene was modified with polydopamine via an in-situ polymerization method. By adjusting the initial pH value in the film formation process, the transition from electrostatic repulsion to hydrogen bonding between graphene@polydopamine and polyacrylate was engineered for improving the mechanical properties. At optimal pH value, the maximum tensile strength of the composite is enhanced by 137% compared with that of neat polymer matrix. Moreover, the composite with filler loading of 20 wt% exhibits an EMI shielding effectiveness of 58 dB at 0.6 mm thickness and thermal conductivity of 1.68 W/m·K, respectively. The practical application of the composite film and composite coated leather also demonstrates their outstanding flexibility, EMI shielding, and heat dissipation performance, indicating their excellent potential as EMI shielding and thermally conductive materials in wide areas such as wearable devices, telecommunication systems, and human protection.