(510a) Lyotropic Liquid Crystals and Aligned Films from Synergistic Self-Assembly of Boron Nitride Nanotubes and Cellulose Nanocrystals

Boron nitride nanotubes (BNNTs) have obtained widespread interest due to their extraordinary thermal, chemical, and mechanical properties. These properties are favorable for a large variety of applications, such as in aerospace, energy, and heat management systems. To effectively translate these properties to macroscopic assemblies, structured ordering of BNNTs is crucial. Cellulose nanocrystals (CNCs) have demonstrated the capability of forming chiral nematic liquid crystals and producing aligned structures of other nanomaterials by acting as a template. In this study, we have demonstrated the synergistic self-assembly of ordered BNNTs in aqueous dispersions of CNCs. Particularly, the critical phase transition concentrations and liquid crystalline phase behavior of BNNT/CNC mixtures were characterized through cross-polarized light and circularly polarized light optical microscopy, as well as rheology. Additionally, solid aligned films were obtained from CNC-templated BNNT liquid crystals. This work lays the foundation for future studies in the manufacturing of stable, lightweight, and thermally conductive aligned assemblies, such as thin films and fibers, for a variety of situations where thermal management is essential.