Sakuma Wataru, Fujisawa Shuji, Berglund Lars A, Saito Tsuguyuki
Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Department of Fibre and Polymer Technology, Wallenberg Wood Science Center, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
Nanomaterials (Basel). 2021 Nov 12;11(11):3032. doi: 10.3390/nano11113032.
Cellulose nanofibers (CNFs) have excellent properties, such as high strength, high specific surface areas (SSA), and low coefficients of thermal expansion (CTE), making them a promising candidate for bio-based reinforcing fillers of polymers. A challenge in the field of CNF-reinforced composite research is to produce strong and transparent CNF/polymer composites that are sufficiently thick for use as load-bearing structural materials. In this study, we successfully prepared millimeter-thick, transparent CNF/polymer composites using CNF xerogels, with high porosity (70%) and high SSA (350 m g), as a template for monomer impregnation. A methacrylate was used as the monomer and was cured by UV irradiation after impregnation into the CNF xerogels. The CNF xerogels effectively reinforced the methacrylate polymer matrix, resulting in an improvement in the flexural modulus (up to 546%) and a reduction in the CTE value (up to 78%) while maintaining the optical transparency of the matrix polymer. Interestingly, the composites exhibited flame retardancy at high CNF loading. These unique features highlight the applicability of CNF xerogels as a reinforcing template for producing multifunctional and load-bearing polymer composites.
纤维素纳米纤维（CNFs）具有优异的性能，如高强度、高比表面积（SSA）和低热膨胀系数（CTE），使其成为聚合物生物基增强填料的有前途的候选材料。CNF增强复合材料研究领域的一个挑战是制备出足够厚、强度高且透明的CNF/聚合物复合材料，以用作承重结构材料。在本研究中，我们使用具有高孔隙率（约70%）和高比表面积（约350 m²/g）的CNF干凝胶作为单体浸渍的模板，成功制备出了毫米厚的透明CNF/聚合物复合材料。使用甲基丙烯酸酯作为单体，将其浸渍到CNF干凝胶中后通过紫外线照射进行固化。CNF干凝胶有效地增强了甲基丙烯酸酯聚合物基体，在保持基体聚合物光学透明度的同时，使弯曲模量提高（高达546%），CTE值降低（高达78%）。有趣的是，在高CNF负载量下，复合材料表现出阻燃性。这些独特特性突出了CNF干凝胶作为制备多功能承重聚合物复合材料的增强模板的适用性。
