Yang Jianming, Wang Hongqiang, Zhou Bin, Shen Jun, Zhang Zhihua, Du Ai
Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai 200092, People's Republic of China.
Langmuir. 2021 Feb 16;37(6):2129-2139. doi: 10.1021/acs.langmuir.0c03312. Epub 2021 Jan 27.
Direct ink writing (DIW) of aerogels has great potential in designing novel three-dimensional (3D) multifunctional materials with hierarchical structures ranging from the nanoscale to the macroscopic scale. In this paper, pure aerogels composed of inorganics, strongly cross-linking organics, and weakly cross-linking organics were directly written via the precise control of the gelation degree without using any additives. The rheological properties of a resorcinol-formaldehyde aerogel-based sol-gel ink (marked as RA ink) were measured at different reaction times to determine the suitable printable range (': several 10 Pa) that ensures its good print fidelity. In addition, the rheological evolution of the RA ink during the sol-gel process and under different shear stresses was studied. The correlation of relevant parameters was established according to the Hagen-Poiseuille model. Other typical aerogel-based sol-gel inks including a silica aerogel-based sol-gel ink (SA ink) and a polyimide aerogel-based sol-gel ink (PA ink) for DIW were also demonstrated. Finally, water evaporation experiments were carried out using a 3D-printed carbonized resorcinol-formaldehyde aerogel (CA) to further exhibit the potential applications of this novel technology in solar steam generation. The evaporation rate (1.57 kg m h) and efficiency (88.38%) of 3D-printed CA were higher than those of bulk CA (1.21 kg m h and 69.82%). This paper systematically studies the control of DIW parameters for aerogel-based sol-gel inks and shows a potential application in high-efficiency 3D-printed evaporators.
气凝胶的直接墨水书写（DIW）在设计具有从纳米尺度到宏观尺度的分级结构的新型三维（3D）多功能材料方面具有巨大潜力。本文通过精确控制凝胶化程度，在不使用任何添加剂的情况下直接书写由无机物、强交联有机物和弱交联有机物组成的纯气凝胶。在不同反应时间测量了基于间苯二酚 - 甲醛气凝胶的溶胶 - 凝胶墨水（标记为RA墨水）的流变特性，以确定确保其良好打印保真度的合适可打印范围（：几十帕斯卡）。此外，研究了RA墨水在溶胶 - 凝胶过程中和不同剪切应力下的流变演变。根据哈根 - 泊肃叶模型建立了相关参数的相关性。还展示了用于DIW的其他典型的基于气凝胶的溶胶 - 凝胶墨水，包括基于二氧化硅气凝胶的溶胶 - 凝胶墨水（SA墨水）和基于聚酰亚胺气凝胶的溶胶 - 凝胶墨水（PA墨水）。最后，使用3D打印的碳化间苯二酚 - 甲醛气凝胶（CA）进行了水蒸发实验，以进一步展示这项新技术在太阳能蒸汽产生中的潜在应用。3D打印CA的蒸发速率（1.57 kg m h）和效率（88.38%）高于块状CA（1.21 kg m h和69.82%）。本文系统地研究了基于气凝胶的溶胶 - 凝胶墨水的DIW参数控制，并展示了其在高效3D打印蒸发器中的潜在应用。
