Construction of surface-functionalized hexagonal boron nitride flakes for unsaturated polyesters resin composites with improved tribological properties under seawater condition

To improve the dispersion and interfacial interaction, surface-functionalized hexagonal boron nitride (h-BN) was prepared by grafting sucrose and hyperbranched polysiloxane (HBPSi) with terminal amino groups. The morphology observation revealed that the surface functionalization improved the interfacial interaction and precluded the h-BN stacking, resulting in the uniform dispersion of sucrose and HBPSi modified boron nitride (HBPSi-BN) in the unsaturated polyester resin (UPR). The UPR/HBPSi-BN composite exhibited the lowest coefficient of friction (0.14) and volume wear rate (2.4 × 10−5 mm3/N·m), which were reduced by 65.1% and 82.6%, respectively, as compared with those of pure UPR. The presence of HBPSi helped to the formation of the compact continuous debris-forming films on the wear surface, reducing the direct contact between friction pairs. The large amount of terminal amino groups from HBPSi could improve the interfacial interaction between fillers and polymer matrix, contributing to the load transform during the sliding friction process. In addition, the high conductivity of HBPSi-BN could also alleviate abrasive wear due to it helped the dissipation of the friction heat at the counterface to reduce plastic deformation, resulting in enhanced tribological properties. This work provides a feasible way for the practical application of commercial h-BN as a low-friction lubricant for polymer composites.