(30i) Lyotropic Liquid Crystals of Cellulose Nanocrystal/Boron Nitride Nanotube Mixtures: Phase Behavior and Aligned Assemblies

Liquid crystals of one-dimensional (1D) boron nitride nanotubes (BNNTs) can be utilized to manufacture strong, multifunctional solid assemblies such as films and fibers with improved alignment and properties. Cellulose nanocrystals (CNCs) are known to form lyotropic liquid crystals and have been utilized as a structural template for nanomaterial assembly. Here, aqueous dispersions of BNNTs were stabilized by carboxymethyl cellulose nanofibers (CM-CNF) via noncovalent complexation. The individually dispersed BNNTs were then incorporated into aqueous dispersions of CNCs to obtain liquid crystals and the phase behavior of BNNT/CNC mixtures with increasing concentrations of BNNTs were studied using polarized light optical microscopy and rheology. Additionally, the wet spinning method was utilized to obtain solid fibers from BNNT/CNC mixtures with improved nanorod alignment and the resulting mechanical properties were measured. Fiber spinning from liquid crystals of BNNT/CNC mixtures can potentially better translate the alignment and properties of nanorods to macroscopic assemblies, which will lead to developing BNNT-based applications in many areas ranging from thermal management to multifunctional textiles.