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Synthesis of Smart Mesoporous Materials

Published online by Cambridge University Press:  10 February 2011

G.V.Rama Rao
Affiliation:
Center for Micro-Engineered Materials, Department of Chemical and Nuclear Engineering, The University of New Mexico, NM 87131
Qiang Fu
Affiliation:
Center for Micro-Engineered Materials, Department of Chemical and Nuclear Engineering, The University of New Mexico, NM 87131
Linnea K. Ista
Affiliation:
Center for Micro-Engineered Materials, Department of Chemical and Nuclear Engineering, The University of New Mexico, NM 87131
Huifang Xu
Affiliation:
Department of Earth and Planetary Sciences.
S. Balamurugan
Affiliation:
Department of Earth and Planetary Sciences.
Larry A. Sklar
Affiliation:
Cancer Center, Department of Pathology, University School of Medicine.
Timothy L. Ward
Affiliation:
Center for Micro-Engineered Materials, Department of Chemical and Nuclear Engineering, The University of New Mexico, NM 87131
Gabriel P. López
Affiliation:
Center for Micro-Engineered Materials, Department of Chemical and Nuclear Engineering, The University of New Mexico, NM 87131
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Abstract

This study details development of hybrid mesoporous materials in which molecular transport through mesopores can be precisely controlled and reversibly modulated. Mesoporous silica materials formed by surfactant templating were modified by surface initiated atom transfer radical polymerization of poly(N-isopropyl acrylamide) (PNIPAAm) a stimuli responsive polymer (SRP) within the porous network. Thermo gravimetric analysis and FTIR spectroscopy were used to confirm the presence of PNIPAAm on the silica surface. Nitrogen porosimetry, transmission electron microscopy and X-ray diffraction analyses confirmed that polymerization occurred uniformly within the porous network. Uptake and release of fluorescent dyes from the particles was monitored by spectrofluorimetry and scanning laser confocal microscopy. Results suggest that the presence of PNIPAAm, a SRP, in the porous network can be used to modulate the transport of aqueous solutes. At low temperature, (e.g., room temperature) the PNIPAAm is hydrated and extended and inhibits transport of analytes; at higher temperatures (e.g., 50°C) it is hydrophobic and is collapsed within the pore network, thus allowing solute diffusion into or out of the mesoporous silica. The transition form hydrophilic to hydrophobic state on polymer grafted mesoporous membranes was determined by contact angle measurements. This work has implications for the development of materials for the selective control of transport of molecular solutes in a variety of applications.

Type
Research Article
Copyright
Copyright © Materials Research Society 2003

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