Functional Composite Materials Research Center, Institute of Advanced Composites Materials, Korea Institute of Science and Technology, Wanju, Jeonbuk 55324, Republic of Korea.
Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea.
ACS Appl Mater Interfaces. 2023 May 24;15(20):24681-24692. doi: 10.1021/acsami.3c00189. Epub 2023 May 10.
Microfiber fabrication via wet-spinning of lyotropic liquid crystals (LCs) with anisotropic nanomaterials has gained increased attention due to the microfibers' excellent physical/chemical properties originating from the unidirectional alignment of anisotropic nanomaterials along the fiber axis with high packing density. For wet-spinning of the microfibers, however, preparing lyotropic LCs by achieving high colloidal stability of anisotropic nanomaterials, even at high concentrations, has been a critically unmet prerequisite, especially for recently emerging nanomaterials. Here, we propose a cationically charged polymeric stabilizer that can efficiently be adsorbed on the surface of boron nitride nanotubes (BNNTs), which provide steric hindrance in combination with Coulombic repulsion leading to high colloidal stability of BNNTs up to 22 wt %. The BNNT LCs prepared from the dispersions with various stabilizers were systematically compared using optical and rheological analysis to optimize the phase behavior and rheological properties for wet-spinning of the BNNT LCs. Systematic optical and mechanical characterizations of the BNNT microfibers with aligned BNNTs along the fiber axis revealed that properties of the microfibers, such as their tensile strength, packing density, and degree of BNNT alignment, were highly dependent on the quality of BNNT LCs directly related to the types of stabilizers.
由于各向异性纳米材料沿纤维轴的单向排列和高堆积密度，使微纤维具有优异的物理/化学性能，因此通过各向异性纳米材料的溶致液晶（LC）湿法纺丝来制备微纤维引起了人们越来越多的关注。然而，对于湿法纺丝微纤维来说，通过实现各向异性纳米材料的高胶体稳定性来制备溶致 LCs 是一个至关重要的未满足的前提条件，尤其是对于最近出现的纳米材料。在这里，我们提出了一种带正电荷的聚合物稳定剂，它可以有效地吸附在氮化硼纳米管（BNNTs）的表面上，与库仑斥力相结合，提供空间位阻，从而使 BNNTs 的胶体稳定性高达 22wt%。使用光学和流变分析系统地比较了用各种稳定剂制备的 BNNT LC，以优化用于 BNNT LC 湿法纺丝的相行为和流变性能。对沿纤维轴排列的 BNNTs 的 BNNT 微纤维进行了系统的光学和力学表征，结果表明，微纤维的性能，如拉伸强度、堆积密度和 BNNT 排列程度，高度依赖于与稳定剂类型直接相关的 BNNT LC 的质量。
