Abstract/Details

Replication of ordered block copolymer templates for the preparation of porous metal oxides in supercritical carbon dioxide


2005 2005

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Abstract (summary)

Ordered nanostructured materials are of enormous interest in photonics, sensing and detection arrays, catalysis, separations, microfluidics and low dielectric constant (low k) thin films. The traditional approach to preparation of these nanostructured films involves cooperative self-assembly of organic templates (including surfactants) and precursor molecules in solution. The approach has been successful in controlling the pore order at the local length scale, but has limited promise for controlling long-range pore order and orientation over the length scales of the device.

We have developed a novel technique for the preparation of nanostructured metal oxide films by a rapid replication procedure of structured organic templates in supercritical carbon dioxide. The technique enables us to separate the self-assembly of the ordered template film from the formation of the metal oxide network. The structure of the pre-formed template on both the local and device levels can be achieved in three dimensions using established techniques prior to infusion of the inorganic phase. This approach also offers flexibility with regard to framework chemistry and the nature of the copolymer template, which can now be chosen independently without regard to compatibility in solution or concerns about disrupting the coordinated self-assembly process. The application of the technique to preparation of ordered mesostructured silicate/organosilicate films with dielectric constants below 2.2 and desirable mechanical properties is discussed.

Post-synthesis treatments of mesostructured silicate and organosilicate films were also investigated with the aim of reducing the shrinkage associated with the template removal by calcination. In addition, blends of semicrystalline amphiphilic block copolymers and amorphous homopolymers was also studied to improve the wetting properties and reduce the crystallinity. Mesostructured silicate and organosilicate films that were templated with the blends exhibited a higher degree of mesostructural order as compared to the films templated by the amphiphilic block copolymers only.

Indexing (details)


Subject
Chemical engineering;
Materials science;
Polymers
Classification
0542: Chemical engineering
0794: Materials science
0495: Polymers
Identifier / keyword
Applied sciences; Pure sciences; Block copolymer; Metal oxides; Porous; Replication; Supercritical carbon dioxide
Title
Replication of ordered block copolymer templates for the preparation of porous metal oxides in supercritical carbon dioxide
Author
Pai, Rajaram Achut
Number of pages
178
Publication year
2005
Degree date
2005
School code
0118
Source
DAI-B 66/02, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
ISBN
9780496976812, 0496976818
Advisor
Watkins, James J.
University/institution
University of Massachusetts Amherst
University location
United States -- Massachusetts
Degree
Ph.D.
Source type
Dissertations & Theses
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
3163694
ProQuest document ID
304997386
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
http://search.proquest.com/docview/304997386
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