Doctoral Dissertations

Keywords and Phrases

Aerogels; Chracterization; Crosslinking; Nanomorphology; Polyurethane; Silica

Abstract

"Aerogels are very low density, light weight open pore materials. A hypothesis that is under intense current investigation by the scientific community states that the mechanical properties of nanostructured polymers depend on their nanomorphology. Aerogels are nanostructured ultra-lightweight nanoporous materials with skeletal frameworks that can display a wide range of nanomorphologies. Thereby aerogels comprise a suitable platform for testing not only that hypothesis but also a wide range of other properties such as light scattering for applications, for example, in thermally insulating windows.

To study the mechanical properties of nanostructured matter as a function of nanomorphology, various shape-memory polyurethane aerogels were prepared with identical density, porosity, and chemical composition, but with vastly different nanostructures. Based on 5 different catalysts at 5 different concentrations each, the elastic modulus of all materials followed a well-defined trend whereas, all other factors being equal, bicontinuous structures were by several times stiffer than spheroidal nanostructures.

In order to develop silica aerogels as thermal insulators for windows, one must achieve a balance of clarity, strength, and thermal insulation value. Light scattering (haze) was studied with an integrating sphere, thermal conductivity with the hot plate method and mechanical strength with uniaxial compression. Delamination of wet-gels from glass substrates during drying into aerogels was traced to the nature mass fractal of the secondary particles that allows them to merge with one another"--Abstract, page v.

Advisor(s)

Leventis, Nicholas
Sotiriou-Leventis, Lia

Committee Member(s)

Nath, Manashi
Grubbs, Garry S.
Chandrashekhara, K.

Department(s)

Chemistry

Degree Name

Ph. D. in Chemistry

Sponsor(s)

National Science Foundation (U.S.)

Comments

The authors thank the NSF under Award No. 1530603 for financial support.

Publisher

Missouri University of Science and Technology

Publication Date

Summer 2019

Journal article titles appearing in thesis/dissertation

  • Light scattering and haze in TMOS-co-APTES silica aerogels
  • Optimized transparent, mechanically strong, thermally insulating crosslinked silica aerogels for energy-efficient windows
  • Experimental deconvolution of depressurization from capillary shrinkage during drying of silica wet-gels with SCF CO₂ .Why aerogels shrink?
  • Nanomorphology dependent mechanical properties: A case study based on polyurethane aerogels

Pagination

xix, 212 pages

Note about bibliography

Includes bibliographic references.

Rights

© 2019 Chandana Mandal, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Thesis Number

T 11596

Electronic OCLC #

1119724013

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