Lower Critical Solubility Temperature Behavior in Membranes Formed from a 2-(2-Methoxyethoxy)ethoxy-Containing Polyphosphazene
A phosphazene polymer with three pendant groups was synthesized and characterized as a membrane material. Substitution of the phosphazene with 64% 2-(2-methoxyethoxy)ethanol (MEE), 27% 4-methoxyphenol, and 9% 2-allyphenol yielded a hydrophilic elastomer with considerable flow at room temperature. Solution behavior showed significant aging effects where, using fresh solutions, membranes could not cast on porous ceramic supports (0.2-micron pore size) without significant polymer penetration into the pores. Solutions aged for two weeks were found to readily penetrate into the pores of the ceramic support. Analysis of fresh and aged solutions by laser light scattering showed significant loss in molecular weight with time. Pervaporation of water-dye solutions using dimensionally stabilized membranes revealed in inverse correlation between flux and temperature, suggesting thermally induced morphological changes within the polymer. This polymer was found to exhibit, in the bulk state, lower critical solubility temperature (LCST) behavior where the material becomes less hydrophilic with increasing temperature. LCST behavior was probed thermally and gravimetrically and has been attributed to the anomalous pervaporation results. The degree to which LCST effects membrane transport was influenced by changes in the crosslink density and permeate side pressure.
- Research Organization:
- Idaho National Lab. (INL), Idaho Falls, ID (United States)
- Sponsoring Organization:
- N/A (US)
- DOE Contract Number:
- AC07-99ID13727
- OSTI ID:
- 804027
- Report Number(s):
- INEEL/JOU-02-00390; JMESDO; TRN: US200302%%399
- Journal Information:
- Journal of Membrane Science, Other Information: PBD: 26 Mar 2002; ISSN 0376-7388
- Country of Publication:
- United States
- Language:
- English
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