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Nature

Title:		Additive manufacturing of silica aerogels
Author(s):		Zhao S; Siqueira G; Drdova S; Norris D; Ubert C; Bonnin A; Galmarini S; Ganobjak M; Pan Z; Brunner S; Nystrom G; Wang J; Koebel MM; Malfait WJ;
Address:		"Laboratory for Building Energy Materials and Components, Swiss Federal Laboratories for Materials Science and Technology, Empa, Dubendorf, Switzerland. shanyu.zhao@empa.ch. Cellulose and Wood Materials Laboratory, Swiss Federal Laboratories for Materials Science and Technology, Empa, Dubendorf, Switzerland. Institute of Environmental Engineering, ETH Zurich, Zurich, Switzerland. Laboratory for Advanced Analytical Technologies, Swiss Federal Laboratories for Materials Science and Technology, Empa, Dubendorf, Switzerland. Laboratory for Building Energy Materials and Components, Swiss Federal Laboratories for Materials Science and Technology, Empa, Dubendorf, Switzerland. Swiss Light Source, Paul Scherrer Institute, Villigen, Switzerland. Faculty of Architecture, Slovak University of Technology in Bratislava, Bratislava, Slovakia. State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, China. Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland. Laboratory for Building Energy Materials and Components, Swiss Federal Laboratories for Materials Science and Technology, Empa, Dubendorf, Switzerland. wim.malfait@empa.ch"
Journal Title:		Nature
Year:		2020
Volume:		20200819
Issue:		7821
Page Number:		387 - 392
DOI:		10.1038/s41586-020-2594-0
ISSN/ISBN:		1476-4687 (Electronic) 0028-0836 (Linking)
Abstract:		"Owing to their ultralow thermal conductivity and open pore structure(1-3), silica aerogels are widely used in thermal insulation(4,5), catalysis(6), physics(7,8), environmental remediation(6,9), optical devices(10) and hypervelocity particle capture(11). Thermal insulation is by far the largest market for silica aerogels, which are ideal materials when space is limited. One drawback of silica aerogels is their brittleness. Fibre reinforcement and binders can be used to overcome this for large-volume applications in building and industrial insulation(5,12), but their poor machinability, combined with the difficulty of precisely casting small objects, limits the miniaturization potential of silica aerogels. Additive manufacturing provides an alternative route to miniaturization, but was 'considered not feasible for silica aerogel'(13). Here we present a direct ink writing protocol to create miniaturized silica aerogel objects from a slurry of silica aerogel powder in a dilute silica nanoparticle suspension (sol). The inks exhibit shear-thinning behaviour, owing to the high volume fraction of gel particles. As a result, they flow easily through the nozzle during printing, but their viscosity increases rapidly after printing, ensuring that the printed objects retain their shape. After printing, the silica sol is gelled in an ammonia atmosphere to enable subsequent processing into aerogels. The printed aerogel objects are pure silica and retain the high specific surface area (751 square metres per gram) and ultralow thermal conductivity (15.9 milliwatts per metre per kelvin) typical of silica aerogels. Furthermore, we demonstrate the ease with which functional nanoparticles can be incorporated. The printed silica aerogel objects can be used for thermal management, as miniaturized gas pumps and to degrade volatile organic compounds, illustrating the potential of our protocol"
Keywords:
Notes:		"PubMed-not-MEDLINEZhao, Shanyu Siqueira, Gilberto Drdova, Sarka Norris, David Ubert, Christopher Bonnin, Anne Galmarini, Sandra Ganobjak, Michal Pan, Zhengyuan Brunner, Samuel Nystrom, Gustav Wang, Jing Koebel, Matthias M Malfait, Wim J eng Research Support, Non-U.S. Gov't England 2020/08/21 Nature. 2020 Aug; 584(7821):387-392. doi: 10.1038/s41586-020-2594-0. Epub 2020 Aug 19"