LEE, SK CHENG, SZD WU, ZQ LEE, CJ HARRIS, FW KYU, T YANG, JC 2024-01-21T22:37:36Z 2024-01-21T22:37:36Z 2022-01-11 1993-01 0959-8103 https://pubs.kist.re.kr/handle/201004/146127 Gel/sol and order/disorder transitions can be observed in a segmented rigid-rod polyimide solution at different concentrations and molecular weights. This polyimide was synthesized from 3,3',4,4'-biphenyltetracarboxylic dianhydride and 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl in refluxing 3-cresol in a one-step process. Above about 140-degrees-C, the polymers are completely soluble in 3-cresol in a concentration range up to 12(w/w)%. During cooling, the hot solutions undergo a mechanical sol/gel transition to form thermally reversible gels. In the gel state, an ordered structure develops. Both the gel/sol and order/disorder transitions are dependent upon concentration, temperature, and molecular weight, but the two transitions exhibit different kinetics. Possible mechanisms of these transitions are discussed. English JOHN WILEY & SONS LTD MOLECULAR-WEIGHT AND CONCENTRATION EFFECTS ON GEL SOL TRANSITIONS IN A SEGMENTED RIGID-ROD POLYIMIDE SOLUTION Article 10.1002/pi.4990300117 1 POLYMER INTERNATIONAL, v.30, no.1, pp.115 - 122 POLYMER INTERNATIONAL 30 1 115 122 N scie scopus A1993JY14400016 Polymer Science Polymer Science Article DIFFERENTIAL SCANNING CALORIMETRY ATACTIC POLYSTYRENE SOLUTIONS ISOTACTIC POLYSTYRENE PHYSICAL GELS THERMOREVERSIBLE GELATION DILUTE-SOLUTIONS MACROMOLECULAR STEREOCHEMISTRY LIGHT-SCATTERING MORPHOLOGY PHASE CONCENTRATION GEL SOL TRANSITION KINETICS MOLECULAR WEIGHT ORDER DISORDER TRANSITION SEGMENTED RIGID-ROD POLYIMIDE SOLUTION