Light-scattering study on porous membrane formation by dry-cast process

The phase-separation mechanism during porous membrane formation by the dry-cast process was investigated by the light-scattering method in poly(methyl methacrylate)/ethyl acetate (EA)/2-methyl-2,4-pentanediol system. The evaporation of EA from the cast solution induced the phase separation and thus the porous membrane was obtained. By the light-scattering measurement on the phase-separation kinetics, the phase separation was found to occur by a spinodal decomposition mechanism. As the amount of nonsolvent in the cast solution decreased, the structure growth rate decreased and the growth stopped soon. The obtained porous structure was isotropic rather than asymmetric. The average interpore distances obtained from the SEM observation roughly agreed with the final constant interphase periodic distances measured by the light-scattering method. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 10: 3205–3209, 2002