Yan Mingyuan, Pan Yuelei, Cheng Xudong, Zhang Zhongxin, Deng Yurui, Lun Zhiyi, Gong Lunlun, Gao Mengyao, Zhang Heping
State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui 230027, P. R. China.
Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei City 106335, Taiwan.
ACS Appl Mater Interfaces. 2021 Jun 16;13(23):27458-27470. doi: 10.1021/acsami.1c05334. Epub 2021 Jun 3.
Advanced thermal insulation materials with low thermal conductivity and robustness derived from regenerative resources are badly needed for building energy conservation. Among them, nanofibrillated cellulose aerogels have huge application potential in the field of thermal insulation materials, but it is still a challenge to prepare cellulose aerogels of excellent comprehensive properties in a simple way. Herein, we demonstrate a unidirectional freeze-drying strategy to develop a novel "robust-soft" anisotropic nanofibrillated cellulose aerogel (NFC-Si-T) by integrating nanofibrillated cellulose (NFC) and Si-O-Si bonding networks under the catalytic dehydration of -toluenesulfonic acid (TsOH). The anisotropic structure endows the NFC-Si-T with high flexibility that can be easily bent or even tied with a knot, and in addition, it possesses high Young's modulus (1-3.66 MPa) that can resist the compression weight of 10,000 times of its own weight without deformation. Furthermore, the NFC-Si-T aerogels exhibit anisotropic thermal insulation performances with a low average thermal conductivity (0.028-0.049 W m K). More importantly, the limited oxygen index of the NFC-Si-T reaches up to 42.6-51%, showing excellent flame-retardant performance. Therefore, the "robust-soft" anisotropic NFC-Si-T aerogels can be used as an advanced thermal insulation material for building thermal insulation applications.
建筑节能迫切需要具有低导热性且由可再生资源制成的坚固耐用的先进保温材料。其中，纳米纤化纤维素气凝胶在保温材料领域具有巨大的应用潜力，但以简单的方式制备具有优异综合性能的纤维素气凝胶仍然是一个挑战。在此，我们展示了一种单向冷冻干燥策略，通过在对甲苯磺酸（TsOH）的催化脱水作用下，将纳米纤化纤维素（NFC）与Si-O-Si键网络相结合，来开发一种新型的“坚固-柔软”各向异性纳米纤化纤维素气凝胶（NFC-Si-T）。这种各向异性结构赋予NFC-Si-T高柔韧性，使其可以轻松弯曲甚至打结，此外，它还具有高杨氏模量（1-3.66MPa），能够承受其自身重量10000倍的压缩重量而不变形。此外，NFC-Si-T气凝胶表现出各向异性的保温性能，平均导热系数低（0.028-0.049W m K）。更重要的是，NFC-Si-T的极限氧指数高达42.6-51%，显示出优异的阻燃性能。因此，“坚固-柔软”各向异性NFC-Si-T气凝胶可作为一种先进的保温材料用于建筑保温应用。
