Investigation on the effect of dispersion quality of boron nitride nanotubes using non-covalent functionalization for polymeric composite applications

Abstract

Boron nitride nanotubes (BNNT) is an inorganic analogue of carbon nanotube (CNT), which carbon atoms are fully substituted by boron and nitrogen atoms, arranging in a hexagonal lattice in nature. BNNT is belonged to a novel class of materials with excellent mechanical, electrical insulation, thermal and optical properties. The dispersion quality of BNNT in various media is a critical requirement for its applications in various fields of materials science. However, the reported studies on dispersion of BNNTs are very limited so far. In this thesis, effects of non-covalent functionalization on dispersion quality of BNNTs and corresponding physico-chemical properties of BNNT composites are systematically investigated. The polymers which can be bound on the BNNTs surface by physical adsorption are carefully designed to disperse them in various solvents. Highly stable dispersion of BNNTs in organic and aqueous solvents are successfully prepared with high concentration up to 20 wt% of BNNTs. Owing to the high dispersion stability of BNNTs, a lyotropic BNNT liquid crystal (LC) at high concentration of BNNTs is obtained and the physical properties of the LC are investigated in detail. Finally, liquid crystalline fiber of BNNTs having uniaxially aligned BNNT bundles is fabricated via liquid crystalline fiber spinning. The further development of BNNT spinning will draw a significant attention from researchers in materials science who are looking for the practical applications such as radiation shielding, insulating high thermal conductive materials, and piezo-electric devices.