asymmetric membrane

https://doi.org/10.1351/goldbook.AT06862
membrane constituted of two or more structural planes of non-identical morphologies.
Source:
PAC, 1996, 68, 1479. 'Terminology for membranes and membrane processes (IUPAC Recommendations 1996)' on page 1481 (https://doi.org/10.1351/pac199668071479)