TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Materials: The silicate may be selected from:(a) layered silicates (phyllosilicates), bentonites and preferably montmorillonite/beidilite materials, especially montmorillonite;(b) pillared silicates; and(c) framework silicates (tectosilicates), zeolites and especially clinoptilolite.    TECHNOLOGY FOCUS - POLYMERS - Preferred Materials: The ionomer may be:(a) a cation exchange polymer (with -SO3M, -COOM and/or -PO3M cation exchange groups, where M = H or a monovalent metal cation) in non-cross-linked form or covalently cross-linked and selected from vinyl polymers, aryl main chain polymers, polythiazole, polypyrazole, polypyrrole, polyaniline and/or polythiophene polyaniline;(b) an anion exchange polymer (with -NR3+, pyridinium pyrR+, imidazolium imR+, pyrazolium pyrazR+, triazolium triR+ groups (R = H, alkyl, aryl) and/or other organic basic aromatic and/or non-aromatic groups) in non-cross-linked form or covalently cross-linked and with a backbone selected from vinyl polymers, aryl main chain polymers, polythiazole, polypyrazole, polypyrrole, polyaniline and/or polythiophene polyaniline; or(c) a polymer with a chain containing the cation and anion exchange groups of (a) and (b) and having a backbone of vinyl polymer, aryl main chain polymer, polythiazole, polypyrazole, polypyrrole, polyaniline and/or polythiophene.The ionomer precursor may be a polymer with COHal-, CONR2- or COOR- groups (R = H, alkyl, aryl; Hal = F, Cl, Br, I), a polymer with SO2Hal-, SO2NR2- or SO2OR- groups (R = H, alkyl, aryl; Hal = F, Cl, Br, I), a polymer with PO3Hal2-, PO3(NR2)2- or PO3(OR)2- groups (R = H, alkyl, aryl; Hal = F, Cl, Br, I) or a precursor of an anion exchange polymer with the groups -NR2 (R = H, alkyl, aryl), pyridyl, imidazolyl, pyrazolyl, triazolyl and/or other organic basic aromatic and/or non-aromatic groups. EXAMPLE - Sulfonated polyether ether ketone (70% sulfonation) and 5 wt.% montmorillonite were dissolved in DMAc and evaporated to form a 50 micron thick membrane. The membrane was added to a mold-contaminated aqueous medium. No mold deposits were detected. A control, without montmorillonite, was heavily coated with mold and attacked.