BNNS formation through surface modification of hBN nanopowders with a silane coupling agent
Levent Köroğlu, Erhan Ayas, Nuran Ay
Abstract
The production of BNNSs through the surface modification of nano-sized hBN powders with vinyltrimethoxysilane (VTS) as a silane coupling agent was realized using the newly introduced process route. It aimed to investigate the effects of shear forces generated by ultrasonication and stirring, which were applied during hydroxylation before silanization, and also VTS concentration on surface chemistry, exfoliation, dispersibility, and stabilization of hBN nanopowder. SEM images exhibited that stirring used before ultrasonication throughout hydroxylation improved the dispersibility of BN platelets. Followed by hydroxylation through ultrasonication, the silanization with 0.5 mg/mL VTS resulted in weak absorbances between 1225–995 cm−1 on FTIR spectrum, dispersed and translucent BN platelets, reduction of Raman peak intensity at 1368 cm−1, and an increase of zeta potential (from −10.1 mV to −19.0 mV) as indications of BNNS formation and also improved dispersibility and stability of dispersions. A higher VTS concentration than 0.5 mg/mL concluded with aggregation and poor dispersibility, associated with depletion flocculation. In addition, the number of translucent BN platelets with a lateral size of ∼ 200 nm increased, Raman peak intensity further decreased, and zeta potential reached −28.8 mV after silanization with optimal VTS content (0.5 mg/mL) since both stirring and ultrasonication were applied along hydroxylation. These results indicate the production of thinner BNNSs with high crystallinity and higher dispersion stability.