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Formation of poly‐vinyl‐alcohol structures by supercritical CO 2
Author(s) -
Reverchon E.,
Cardea S.,
Rapuano C.
Publication year - 2007
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.26077
Subject(s) - vinyl alcohol , supercritical fluid , membrane , phase inversion , materials science , solvent , chemical engineering , polymer chemistry , polymer , supercritical carbon dioxide , acetone , porosity , chemistry , organic chemistry , composite material , engineering , biochemistry
Poly‐vinyl‐alcohol (PVA) porous structures have been prepared using a supercritical phase inversion process in which supercritical carbon dioxide (SC‐CO 2 ) acts as the nonsolvent. First, we tested the versatility of the SC‐CO 2 phase inversion process, forming PVA/dimethylsulfoxide (DMSO) solutions with polymer concentrations ranging from 1 to 35% (w/w) and changing the process parameters. We worked at temperatures from 35 to 55°C and pressures from 100 to 200 bar obtaining different membranes morphologies: dense films, membranes with coexisting morphologies, and microparticles. However, we did not produce symmetric or asymmetric porous membranes. To obtain this result, we used casting solutions formed by adding acetone to DMSO with the aim of modifying the affinity between SC‐CO 2 and the liquid solvent. In this series of experiments, we obtained asymmetric membranes with skin layer thicknesses lower than 10 μm. The results obtained in this work have been explained considering that the membranes formation mechanism is related to the kinetics of the process; i.e. the affinity between the solvent (mixture of solvents) and SC‐CO 2 . © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007