In-situ monitoring of asymmetric poly(ethylene-co-vinyl alcohol) membrane formation via a phase inversion process by an ultrasonic through-transmission technique

► An ultrasonic through-transmission technique was developed to monitor asymmetric EVAL membrane formation via the phase inversion of EVAL/DMSO/water system in real-time. ► The movement of the ultrasonic signals increased with an increase membrane formation time. ► The shift rate of the ultrasonic signals decreased with an increase in the EVAL concentration. The shift of the acoustic signals and changes in sound velocity were associated with the double diffusion between DMSO and water. ► Ultrasonic measurements corroborated the observation of membrane morphology and properties.