Processing of surfactant templated nano-structured silica films using compressed carbon dioxide as interpreted from in situ fluorescence spectroscopy

Kaustav Ghosh; Stephen E Rankin; Hans-Joachim Lehmler; Barbara L Knutson

doi:10.1021/jp305113b

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Processing of surfactant templated nano-structured silica films using compressed carbon dioxide as interpreted from in situ fluorescence spectroscopy

Journal article

Peer reviewed

Processing of surfactant templated nano-structured silica films using compressed carbon dioxide as interpreted from in situ fluorescence spectroscopy

Kaustav Ghosh, Stephen E Rankin, Hans-Joachim Lehmler and Barbara L Knutson

The journal of physical chemistry. B, Vol.116(38), pp.11646-11655

09/27/2012

DOI: 10.1021/jp305113b

PMID: 22946494

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Abstract

The local environment and dynamics of compressed carbon dioxide (CO(2)) penetration in surfactant templated silica film synthesis is interpreted from the in situ fluorescence emission spectra of pyrene (Py) and a modified pyrene probe. Pyrene emission in cetyltrimethylammonium bromide (CTAB) and cetylpyridinium bromide (CPB) templated silica films is monitored immediately after casting and during processing with gaseous and supercritical (sc) CO(2) (17-172 bar, 45 °C). The solvatochromic emission spectra of pyrene in CTAB templated films suggest CO(2) penetration in both the micelle interface and its interior. An anchored derivative of pyrene, 1-pyrenehexadecanoic acid (C(16)-pyr), is established for probing CPB films, where the pyrene moiety is preferentially oriented toward the micelle interior, thus limiting quenching by the pyridinium headgroup of CPB. CO(2) processing of CPB templated silica films results in an increase in the time scale for probe mobility, suggesting an increased time scale of silica condensation through CO(2) processing. The mobility of C(16)-pyr increases with pressure from gaseous to sc CO(2) processing and persists for over 5 h for sc CO(2) processing at 172 bar and 45 °C compared to about 25 min for the unprocessed film. The delivery of CO(2) soluble solutes to specific regions of surfactant templated mesoporous materials is examined via the nonradiative energy transfer (NRET) between pyrene and CO(2)-solubilized naphthalene.

Carbon Dioxide - chemistry

Pyrenes - chemistry

Silicon Dioxide - chemical synthesis

Micelles

Silicon Dioxide - chemistry

Models, Molecular

Nanostructures - chemistry

Spectrometry, Fluorescence

Molecular Structure

Surface-Active Agents - chemistry

Details

Title: Subtitle: Processing of surfactant templated nano-structured silica films using compressed carbon dioxide as interpreted from in situ fluorescence spectroscopy
Creators: Kaustav Ghosh - Department of Chemical and Materials Engineering, University of Kentucky, Lexington, Kentucky 40506-0046, USA
Stephen E Rankin
Hans-Joachim Lehmler
Barbara L Knutson
Resource Type: Journal article
Publication Details: The journal of physical chemistry. B, Vol.116(38), pp.11646-11655
DOI: 10.1021/jp305113b
PMID: 22946494
NLM abbreviation: J Phys Chem B
ISSN: 1520-6106
eISSN: 1520-5207
Publisher: American Chemical Society; United States
Language: English
Date published: 09/27/2012
Academic Unit: Occupational and Environmental Health; Iowa Neuroscience Institute
Record Identifier: 9984001079602771

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