Lee, HJ Won, J Lee, H Kang, YS 2024-01-21T11:06:04Z 2024-01-21T11:06:04Z 2021-09-05 2002-02-28 0376-7388 https://pubs.kist.re.kr/handle/201004/139765 Physical properties of poly(amic acid) (PAA) casting solutions in N-methyl-2-pyrrolidone (NMP) containing lithium chloride (LiCl) were characterized by viscometry and dynamic light scattering (DLS) and were related to the morphological properties of asymmetric membranes prepared from these solutions. At a fixed polymer concentration, the increase in viscosity of the PAA solutions with increasing LiCl content is mainly determined by the viscosity of the salt-solvent medium, implying that the LiCl-NMP interactions are stronger than those between LiCl and PAA. Because of the strong salt-solvent interactions, complexes b.-tween LiCl and NMP are formed. The complexes reduce the solvent power of NMP for PAA inducing polymer aggregation (clustering) and/or transient cross-links in the solutions. Dynamic light scattering results for salt-containing solutions at low PAA concentrations support the existence of these aggregations. Solutions without salt showed a single relaxation, but solutions with LiCl exhibit multiple relaxation modes; two diffusional modes of cooperative and aggregates, and one angle independent transient network mode. The polymer aggregates and transient cross-links form a gel-like structure in the casting solution film and hinder macrovoid formation during phase inversion, resulting in asymmetric membranes with a primarily sponge-like structure. (C) 2002 Elsevier Science B.V. All rights reserved. English ELSEVIER SCIENCE BV DYNAMIC LIGHT-SCATTERING DOPE SOLUTION CHARACTERISTICS SEMIDILUTE POLYMER-SOLUTIONS GAS-TRANSPORT PROPERTIES THREAD-LIKE MICELLES ETHYL-ACETATE LITHIUM-CHLORIDE BEHAVIOR CELLULOSE SYSTEM Solution properties of poly(amic acid)-NMP containing LiCl and their effects on membrane morphologies Article 10.1016/S0376-7388(01)00610-X 1 JOURNAL OF MEMBRANE SCIENCE, v.196, no.2, pp.267 - 277 JOURNAL OF MEMBRANE SCIENCE 196 2 267 277 scie scopus 000172410000013 2-s2.0-0037186179 Engineering, Chemical Polymer Science Engineering Polymer Science Article DYNAMIC LIGHT-SCATTERING DOPE SOLUTION CHARACTERISTICS SEMIDILUTE POLYMER-SOLUTIONS GAS-TRANSPORT PROPERTIES THREAD-LIKE MICELLES ETHYL-ACETATE LITHIUM-CHLORIDE BEHAVIOR CELLULOSE SYSTEM poly(amic acid) viscosity dynamic light scattering LiCl