Doctoral Dissertations

Alternative Title

Tour de force in polymer crosslinked aerogels

Author

Sudhir Mulik

Abstract

"In the quest of building mechanically strong materials with low density and high porosity, polymer crosslinked aerogels stand as the most promising nano-engineered examples. Covalent attachment of polymers and bridging of skeletal nanoparticles of typical aerogels is demonstrated by using surface initiated polymerization (SIP) with a bidentate free-radical initiator structurally related to azobisisobutyronitrile (AIBN) and confined on mesoporous silica surfaces. Different monomers were introduced in the mesopores and upon heating at 70⁰C, all mesoporous surfaces throughout the entire skeletal framework were coated conformally with a 10-12 nm thick polymer layer indistinguishable spectroscopically from the respective commercial bulk materials. The new materials combine hydrophobicity with vastly improved mechanical properties. Resorcinol formaldehyde (RF) aerogels are pursued as precursors of carbon aerogels, which are electrically conducting. We have developed a HCl-catalyzed gelation process in CH₃CN, which is completed in ~ 2 h at room temperature as opposed to the week-long base-catalyzed literature process. The final aerogels are spectroscopically indistinguishable from typical base-catalyzed samples. Carbon (C-) aerogels are made by pyrolysis of RF aerogels, and combine electrical conductivity with a high open mesoporosity. Nevertheless, macropores facilitate mass-transfer and they could be beneficial for applications in separations or as fuel cell and battery electrodes. Here, we report a method where an open macroporosity is introduced by pyrolysing RF aerogels whose skeletal nanoparticles have been coated conformally and crosslinked chemically with an isocyanate-derived polymer. The new macroporous material was evaluated electrochemically for possible application as an electrode in batteries and fuel cells"--Abstract, page iv.

Advisor(s)

Leventis, Nicholas
Sotiriou-Leventis, Lia

Committee Member(s)

Stoffer, James O.
Whitefield, Philip D.
Isaac, Kakkattukuzhy M.

Department(s)

Chemistry

Degree Name

Ph. D. in Chemistry

Publisher

Missouri University of Science and Technology

Publication Date

Summer 2008

Journal article titles appearing in thesis/dissertation

  • Crosslinking 3D assemblies of nanoparticles into mechanically strong aerogels by surface-initiated free radical polymerization
  • Time-efficient acid-catalyzed synthesis of resorcinol-formaldehyde aerogels
  • Macroporous electrically conducting carbon networks by pyrolysis of isocyanate-crosslinked resorcinol-formaldehyde aerogels

Pagination

xv, 146 pages

Note about bibliography

Includes bibliographical references.

Rights

© 2008 Sudhir M. Mulik, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Library of Congress Subject Headings

Aerogels
Crosslinking (Polymerization)
Mesoporous materials

Thesis Number

T 9794

Print OCLC #

775796104

Electronic OCLC #

758385080

Included in

Chemistry Commons

Share

 
COinS