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Article

pH-Responsive Thin Film Membranes from Poly(2-vinylpyridine): Water Vapor-Induced Formation of a Microporous Structure

Maxim Orlov,^† Ihor Tokarev,^† Andreas Scholl,^‡ Andrew Doran,^‡ and Sergiy Minko*^†

Department of Chemistry and Biomolecular Science, Clarkson University, Potsdam, New York 13699, and Lawrence Berkeley National Laboratory, Berkeley, California 94720

Macromolecules, 2007, 40 (6), pp 2086–2091

DOI: 10.1021/ma062821f

Publication Date (Web): February 27, 2007

†

Clarkson University.

‡

Lawrence Berkeley National Laboratory.

Corresponding author. E-mail sminko@clarkson.edu.

Abstract

We report the fabrication of microporous thin film membranes with two-dimensionally arranged submicron pores whose size can be varied by changing pH of aqueous medium. A solution containing poly(2-vinylpyridine) partially quaternized with 1,4-diiodobutane (qP2VP) and unreacted 1,4-diodobutane (DIB) was used for the formation and deposition of the membranes on solid substrates. The membranes were spin-coated onto solid substrates in a controlled humid environment. The presence of water vapor in air was found to be a necessary condition for the pore formation. We studied the influence of relative humidity on the membrane morphology and proposed a mechanism of pore formation. Cross-linking the qP2VP membranes with DIB made them insoluble (stable) in organic solvents and acidic water. The cross-linked membranes demonstrated pH-dependent swelling, which had a strong influence on the pore size.

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