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Synthesis and Tuning of Bimodal Mesoporous Silica by Combined Hydrocarbon/Fluorocarbon Surfactant Templating
Journal article   Peer reviewed

Synthesis and Tuning of Bimodal Mesoporous Silica by Combined Hydrocarbon/Fluorocarbon Surfactant Templating

Rong Xing, Hans-Joachim Lehmler, Barbara L Knutson and Stephen E Rankin
Langmuir, Vol.25(11), pp.6486-6492
06/02/2009
DOI: 10.1021/la9000939
PMID: 19323503

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Abstract

Hydrocarbon and fluorocarbon surfactants show highly nonideal mixing that under some conditions results in demixing of the two types of surfactants into distinct populations of fluorocarbon-rich and hydrocarbon-rich aggregates. This also occurs in materials prepared by cooperative assembly of hydrolyzed tetraethoxysilane with mixtures of cetyltrimethylammonium chloride (CTAC) and 1,1,2,2-tetrahydro-perfluorodecylpyridinium chloride (HFDePC). Here, we report conditions under which demixed micelles lead to bimodal mesoporous materials (including specific concentrations of ammonia and salt in the synthesis solution) and show that the sizes of the hydrocarbon-templated and fluorocarbon-templated pores can be finely and independently controlled by adding lipophilic or fluorophilic oils, respectively. Nitrogen sorption isotherms and transmission electron microscopy provide clear evidence for a single phase of demixed but disordered wormhole-like pores.
Materials: Nano-and Mesostructured Materials, Polymers, Gels, Liquid Crystals, Composites

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