Formation of microporous polymer fibers and oriented fibrils by precipitation with a compressed fluid antisolvent

摘要: Polymer morphology is controlled over a continuum from microspheres to interconnected bicontinuous networks fibers with versatile new process: precipitation compressed fluid antisolvent. The results are explained qualitatively as function of phase behavior, mass-transfer pathways, and the formation rates skin on flowing jet. By spraying dilute polystyrene in toluene solutions into liquid carbon dioxide, extremely small 100 nm formed. For concentrations above critical composition, produced that not only microcellular, but, some instances, even hollow. Mass-transfer pathways cross binodal near composition produce networks, likely due spinodal decomposition. In this region, composed highly oriented microfibrils at high shear rates. Preaddition CO2 influences because dilution, similar manner antisolvent, except viscosity reduction larger added free volume. Because diffuses through glassy faster than does conventional antisolvent such methanol, it produces more porous fibers, which also cylindrical. © 1993 John Wiley & Sons, Inc.