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Large- and small-nanopore silica prepared with a short-chain cationic fluorinated surfactant
Journal article   Peer reviewed

Large- and small-nanopore silica prepared with a short-chain cationic fluorinated surfactant

Bing Tan, Hans-Joachim Lehmler, Sandhya M Vyas, Barbara L Knutson and Stephen E Rankin
Nanotechnology, Vol.16(7), pp.S502-S507
07/2005
DOI: 10.1088/0957-4484/16/7/026
PMID: 21727471

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Abstract

A cationic partially fluorinated surfactant with four carbons in the chain 1-(3,3,4,4,4-pentafluorobutyl)pyridinium chloride is employed as a structure-directing agent to synthesize nanoporous silica. Samples are prepared in dilute ammonia solutions at room temperature with a range of surfactant:Si ratios. The sample with the largest surfactant:Si ratio forms particles with wormhole-like micropores with an average diameter of 1.6 nm, which corresponds to the anticipated small size of the surfactant aggregates. On the other hand, the sample with the smallest surfactant:Si ratio forms a gel that, upon drying, has uniform 11.1 nm pores. The formation and stabilization of the latter large-mesopore structure is unusual for a sample prepared and dried under ambient conditions, and may reflect favourable roles of the surfactant both in inducing gelation and in stabilizing the pore structure during drying.

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