Constructing a dense dual network of edge-selectively carboxylated graphene in polyamide composites to achieve excellent gas barrier property

Abstract It is still a challenge to fabricate polymer composites with superior gas barrier properties, which is highly demanded in aircraft tire lining with a high gas pressure (1.5 MPa). Herein, a versatile method to fabricate polymer composites with a dense dual network structure via ball-milling was developed. In such a structure, the graphite was in-situ exfoliated to edge-selectively carboxylated graphene (ECG) nanosheets, which were first embedded into ternary copolymerized polyamide (PA) particles to construct an inner well-dispersed network. Subsequently, ECG nanosheets were selectively distributed at the interfaces between resultant particles of PA composites to form an external interconnected network. It was found that the dense dual network of ECG prolongs the pathways for diffusing gas molecules, compared with the pristine PA, up to a 20-fold decrease in nitrogen permeability of ultimate PA composites (from 0.233 × 10−17 to 0.0113 × 10−17 m2 S−1 Pa−1) were obtained with only 2 wt% ECG nanosheets. The excellent gas barrier properties were ascribed to the synergistic effect of the dual network. This work provides an efficient, scalable, low-cost and eco-friendly route to fabricate high-barrier polymer composites.