Monolithic and shrinkage-free hydrophobic silica aerogels via new rapid supercritical extraction process

D. B. Mahadik, Yoon Kwang Lee, N. K. Chavan, S. A. Mahadik, Hyung-Ho Park

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

Aerogels have unusual mechanical and thermal properties and are useful in thermal insulation applications. However, aerogel production can be a tedious process if aerogels are made using supercritical extraction of a solvent from a sol-gel matrix. We employ a new rapid and simple supercritical extraction process that is better than conventional methods. This technique relies on rapid heating of the sol in a confined mold under a 50 bar initial pressure supplied by dry N2 gas in an autoclave. The initial pre-pressure of N2 gas and base catalyst concentration dictate whether aerogels or xerogels are formed. A model is presented based on the various experimental results that predicts that gelation occurred after the solvent reached a supercritical state. Aerogels produced using this new rapid supercritical extraction process are monolithic, shrinkage-free, have a prescribed shape and size, and possess high surface area (∼800 m2/g) and low thermal conductivity (∼0.035-0.041 W/(m K)). The hydrophobicity as measured by water contact angle was enhanced from 119° to 158° using a hydrophobic co-precursor in the sol.

Original languageEnglish
Pages (from-to)84-91
Number of pages8
JournalJournal of Supercritical Fluids
Volume107
DOIs
Publication statusPublished - 2016 Jan 1

Fingerprint

Aerogels
aerogels
shrinkage
Silicon Dioxide
Silica
silicon dioxide
Polymethyl Methacrylate
Sols
Gases
thermal insulation
Xerogels
autoclaves
xerogels
Thermal insulation
Autoclaves
gelation
Gelation
Hydrophobicity
hydrophobicity
gases

All Science Journal Classification (ASJC) codes

  • Chemical Engineering(all)
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry

Cite this

Mahadik, D. B. ; Lee, Yoon Kwang ; Chavan, N. K. ; Mahadik, S. A. ; Park, Hyung-Ho. / Monolithic and shrinkage-free hydrophobic silica aerogels via new rapid supercritical extraction process. In: Journal of Supercritical Fluids. 2016 ; Vol. 107. pp. 84-91.
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Monolithic and shrinkage-free hydrophobic silica aerogels via new rapid supercritical extraction process. / Mahadik, D. B.; Lee, Yoon Kwang; Chavan, N. K.; Mahadik, S. A.; Park, Hyung-Ho.

In: Journal of Supercritical Fluids, Vol. 107, 01.01.2016, p. 84-91.

Research output: Contribution to journalArticle

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