Facile synthesis of high-performance and self-healing polyurethane-urea nanocomposites reinforced with graphene

In this study, a facile method was employed to synthesize strong, yet highly elastic polyurethane-urea (PUU) with typical characteristics and 94 ​% optical transmittance. Graphene platelets (GNPs) were prepared and modified via a scalable and eco-friendly mechanochemical approach. The produced GNPs is at 1.6-nm thickness with high electrical conductivity of ∼950 ​S/m. The structure-property relations of PUU/GNP nanocomposites were comprehensively investigated through morphology and mechanical properties measurements. The strong interface and high-density hydrogen bonds between modified GNPs (M-GNPs) and PUU significantly enhanced the mechanical properties of the PUU nanocomposite. The PUU composite showed 66.7 ​% and 36.2 ​% increments in tensile and impact strengths, respectively, at 0.2 ​wt% M-GNPs. The reversible hydrogen bond between M-GNPs and PUU endowed the nanocomposite with self-healing properties achieving 97.8 ​% healing efficiency of the strength after 5 ​h at 120 ​°C. This study demonstrates the importance of surface modification and provides a simple yet robust approach for preparing high-performance and functional PUU/graphene composites.