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2-Methylpyrazine (2MP), a flavoring agent, was identified and used as a novel greener solvent for nonsolvent-induced phase separation (NIPS) fabrication of poly(ether sulfone) (PES) ultrafiltration (UF) membranes. Flat-sheet membranes were fabricated with 2MP-cosolvent blends, N,N-dimethylacetamide (DMAc), or dimethyl sulfoxide (DMSO), to investigate the influence of solvent choice on membrane properties and performance. The resulting membranes were characterized to assess morphology, productivity, and molecular weight cutoff (MWCO). In addition, kinetic and thermodynamic aspects of solvent choice on the polymer “dope” solutions during the NIPS process were examined. 2MP-cosolvent blends resulted in membranes with noticeably different morphologies, which arise from miscibility-hindered solvent–nonsolvent exchange during membrane formation. Membrane permeance was significantly lower for 2MP-cosolvent membranes when compared to DMAc and DMSO membranes; however, their MWCOs were clearly decreased. This initial study shows that 2MP is a promising greener solvent candidate for NIPS, and further investigations are warranted.
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Mass-transfer driven spinodal decomposition in a ternary polymer solution
Nonsolvent induced phase separation (NIPS) is a widely occuring process used in industrial membrane production, nanotechnology and Nature to produce microstructured polymer materials. A variety of process-dependent morphologies are produced when a polymer solution is exposed to a nonsolvent that, following a period where mass is exchanged, precipitates and solidifies the polymer. Despite years of investigation, both experimental and theoretical, many questions surround the pathways to the microstructures that NIPS can produce. Here, we provide simulation results from a model that simultaneously captures both the processess of solvent/nonsolvent exchange and phase separation. We show that the time it takes the nonsolvent to diffuse to the bottom of the film is an important timescale, and that phase separation is possible at times both much smaller and much larger than this scale. Our results include both one-dimensional simulations of the mass transfer kinetics and two- and three-dimensional simulations of morphologies at both short and long times. We find good qualitative agreement with experimental heuristics, but we conclude that an additional model for the vitrification process will be key for fully explaining experimental observations of microstructure formation.
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- Award ID(s):
- 1725797
- PAR ID:
- 10108553
- Date Published:
- Journal Name:
- Soft Matter
- Volume:
- 15
- Issue:
- 23
- ISSN:
- 1744-683X
- Page Range / eLocation ID:
- 4614 to 4628
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/C9SM00355J
