A top surface liquid layer during membrane formation using vapor-induced phase separation (VIPS)-Evidence and mechanism of formation
Journal
Journal of Membrane Science
Journal Volume
310
Journal Issue
1-2
Pages
278-288
Date Issued
2008
Author(s)
Abstract
The formation of a surface liquid layer on the top of membrane forming systems made of poly(ether-imide) (PEI) and N-methylpyrrolidone (NMP) was clearly demonstrated during water vapor-induced phase separation (VIPS) through several in situ investigation methods including optical microscopy and dynamic water contact angle measurements for a qualitative approach, and Raman confocal and FTIR microscopy for a quantitative one. A mechanism involving the shrinkage from the polymer-rich phase consecutively to the surface phase separation is proposed to account for the significantly high concentration of PEI in the surface liquid layer. The emergence of a surface liquid layer during the phase separation process is discussed in terms of implications on morphology of membrane fabricated using VIPS and how it contrasts with liquid-induced phase separation. ? 2007 Elsevier B.V. All rights reserved.
Subjects
In situ analysis
Membrane morphology
Poly(ether-imide)
Surface liquid layer
Vapor-induced phase separation
Type
journal article