Title: Transparent silica aerogel slabs synthesized from nanoparticle colloidal suspensions at near ambient conditions on omniphobic liquid substrates

Abstract

This paper presents a novel sol-gel method to synthesize large and thick silica aerogel monoliths at near ambient conditions using a commercial aqueous solution of colloidal silica nanoparticles as building blocks. To achieve slabs with high visible transmittance and low thermal conductivity, the method combines the strategies of (i) synthesizing gels on an omniphobic perfluorocarbon liquid substrate, (ii) aging at temperatures above room temperature, and (iii) performing solvent exchange with a low-surface-tension organic solvent prior to ambient drying. The omniphobic liquid substrates were used to prevent cracking and ensure an optically-smooth surface, while nanoparticle building blocks were small (<10 nm) to limit volumetric light scattering. Gels were aged at temperatures between 25 and 80 °C for up to 21 days to make them stronger and stiffer and to reduce shrinkage and cracking during ambient drying. Ambient drying was achieved by first exchanging water in the gel pores for octane, followed by drying in an octane-rich atmosphere to decrease capillary forces. The synthesized nanoparticle-based silica aerogel monoliths had thicknesses up to 5 mm, diameters up to 10 cm, porosities exceeding 80%, and thermal conductivities as low as 0.08 W m^–1 K^–1. Notably, the slabs featured visible transmittance exceeding 75% even formore » slabs as thick as 5 mm. The as-synthesized aerogel monoliths were exposed to TMCS vapor to induce hydrophobic properties resulting in a water contact angle of 140° that prevented water infiltration into the pores and protected the aerogels from water damage. This simple synthesis route conducted at near ambient conditions produces hydrophobic aerogel monoliths with promising optically transparent and thermally insulating properties that can be adhered to glass panes for window insulation and solar-thermal energy conversion applications.« less

Authors:

Marszewski, Michal ^[1]; King, Sophia C. ^[2]; Galy, Tiphaine ^[2]; Kashanchi, Glareh N.  ^[2];

• Search DOE PAGES for author "Kashanchi, Glareh N."
• Search DOE PAGES for ORCID "0000-0002-1206-8737"

Dashti, Ali ^[2]; Yan, Yan ^[2]; Li, Man ^[2]; Butts, Danielle M. ^[2]; McNeil, Patricia E. ^[2]; Lan, Esther ^[2]; Dunn, Bruce ^[2]; Hu, Yongjie  ^[2];

• Search DOE PAGES for author "Hu, Yongjie"
• Search DOE PAGES for ORCID "0000-0001-7225-1130"

Tolbert, Sarah H. ^[2]; Pilon, Laurent  ^[2]

• Search DOE PAGES for author "Pilon, Laurent"
• Search DOE PAGES for ORCID "0000-0001-9459-8207"

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+ Show Author Affiliations

1. Univ. of California, Los Angeles, CA (United States); Univ. of Toledo, OH (United States)
2. Univ. of California, Los Angeles, CA (United States)

Publication Date:

Fri Aug 06 00:00:00 EDT 2021

Research Org.:

Univ. of California, Los Angeles, CA (United States); Stanford Univ., CA (United States); SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States). Stanford Synchrotron Radiation Lightsource (SSRL)

Sponsoring Org.:

USDOE Advanced Research Projects Agency - Energy (ARPA-E); USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1977263

Alternate Identifier(s):

OSTI ID: 1998983

Grant/Contract Number:  

AR0000738; AC02-76SF00515

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Colloid and Interface Science

Additional Journal Information:

Journal Volume: 606; Journal Issue: P1; Journal ID: ISSN 0021-9797

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Chemistry; Aerogel; Ambigel; Mesoporous silica; Liquid substrate; Silica nanoparticles; Optically transparent thermal insulation