Functionalization of boron nitride nanosheets by diazonium salt for preparation of nanocomposites with high-density polyethylene

Functionalization of boron nitride nanosheets (BNNSs) has always been a challenge due to its chemical inertness and anti-oxidative properties. In a concentrated base environment, the B-N bonds on the surface of BNNSs were broken to produce a large number of B-OH and N-H functional groups. Afterwards, aniline carbocation produced by decomposition of the diazonium salt was utilized to achieve high grafting content of Ph-NH 2 groups onto the surface of BNNSs. Further, the amide reaction between amino and stearyl chloride verified the reactivity of Ph-NH 2 groups on the surface of BNNSs, with the result that BNNSs were abundantly decorated by aliphatic chains at 22.9 wt% grafting yield. The surface aliphatic chains of BNNSs strongly improved the interfacial adhesion between the High-density polyethylene (HDPE) matrix and the filler and provided an excellent dispersion of SC-BNNSs in the HDPE matrix. Therefore, HDPE/SC-BNNSs nanocomposites showed improved thermal stability, thermal conductivity, neutron shielding property and flexural modulus with no apparent reduction in tensile strength. When filler content exceeded 5 wt%, the HDPE/SC-BNNSs nanocomposites showed a higher thermal decomposition temperature than the composites with pristine BNNSs fillers. POLYM. COMPOS., 40:2346–2356, 2019. © 2018 Society of Plastics Engineers