Zhang Sizhao, Lu Kunming, Hu Yangbiao, Xu Guangyu, Wang Jing, Liao Yanrong, Yu Shuai
Polymer Aerogels Research Center, Jiangxi University of Science and Technology, Nanchang 330013, China.
Science and Technology on Advanced Ceramic Fibers and Composites Laboratory, National University of Defense Technology, Changsha 410073, China.
Gels. 2024 Mar 21;10(3):210. doi: 10.3390/gels10030210.
The inherent characteristics of cellulose-derived aerogels, such as their natural abundance and environmental friendliness, make them highly interesting. However, its significant shrinkage before and after the supercritical drying procedure and low mechanical strength limit its potential application. Here, we propose a strategy to prepare cellulose diacetate aerogels (CDAAs) with low drying shrinkage, exceptional thermal insulation, and superior mechanical strength. The low drying shrinkage (radial drying shrinkage of 1.4%) of CDAAs is attributed to their relative strong networking skeletons, which are greatly formed by tert-butanol solvent exchange in exerting the interaction of reducing the surface tension force. In this case, CDAAs are eventually endowed with the low bulk density of 0.069 g cm as well. Additionally, as-prepared CDAAs possess an abundant three-dimensional networking structure whose pore size is concentrated in the diameter range of ~50 nm, and the result above is beneficial for improving the thermal insulation performance (thermal conductivity of 0.021 W m K at ambient environmental and pressure conditions). On the other hand, the optimal compressive stresses of CDAAs at 3% and 5% strain are 0.22 and 0.27 MPa respectively, indicating a mechanically well robustness. The above evidence demonstrates indeed the exceptional thermal insulation and superior compressive properties of CDAAs. This work may provide a new solution for developing a kind of high-performance cellulose-derived aerogel in the future.
纤维素衍生气凝胶的固有特性，如天然丰富性和环境友好性，使其极具吸引力。然而，其在超临界干燥过程前后的显著收缩以及低机械强度限制了其潜在应用。在此，我们提出一种制备具有低干燥收缩率、优异隔热性能和卓越机械强度的二醋酸纤维素气凝胶（CDAAs）的策略。CDAAs的低干燥收缩率（径向干燥收缩率为1.4%）归因于其相对较强的网络骨架，这主要是通过叔丁醇溶剂交换形成的，在降低表面张力的相互作用中发挥作用。在这种情况下，CDAAs最终也具有0.069 g/cm³的低堆积密度。此外，所制备的CDAAs具有丰富的三维网络结构，其孔径集中在约50 nm的直径范围内，上述结果有利于提高隔热性能（在环境温度和压力条件下热导率为0.021 W/(m·K)）。另一方面，CDAAs在3%和5%应变下的最佳压缩应力分别为0.22和0.27 MPa，表明其具有良好的机械稳健性。上述证据确实证明了CDAAs具有优异的隔热性能和卓越的压缩性能。这项工作可能为未来开发一种高性能纤维素衍生气凝胶提供新的解决方案。
