NOVELTY - Modified sulfonated block copolymer comprises at least two polymer end blocks A1 and at least one polymer interior block B1, where each A1 block contains essentially no sulfonic acid or sulfonate functional groups and each B1 block comprises sulfonation susceptible monomer units which are substituted sulfonamide compounds (I) and the B1 block comprises 10-100 mol.% of the functional group, based on the number of the sulfonation susceptible monomer units.    USE - The modified sulfonated block copolymer is useful: in membrane or film which is useful in an apparatus (consisting of fuel cells, filtration devices, devices for controlling humidity, devices for forward electrodialysis, devices for reverse electrodialysis, devices for pressure retarded osmosis, devices for forward osmosis, devices for reverse osmosis, devices for selectively adding water, devices for selectively removing water, devices for capacitive deionization, devices for molecular filtration, devices for removing salt from water, devices for treating produced water from hydraulic fracturing applications, devices for ion transport applications or devices for softening water and batteries) and electro-deionization assembly; and in coated article (all claimed); and in protective clothing and breathable fabric applications.    ADVANTAGE - The modified sulfonated block copolymer: exhibits high water vapor transport rates, while having very good dimensional stability, good methanol resistance, easy film or membrane formation, good barrier properties, controlled flexibility and elasticity, adjustable hardness, and thermal/oxidative stability; and provides membrane that exhibit a conductivity of at least 0.5 mS/cm, an anion exchange selectivity of at least 80% and has an water absorption of at most 20 wt.%, based on the dry weight of the membrane.    DETAILED DESCRIPTION - Modified sulfonated block copolymer comprises at least two polymer end blocks A1 and at least one polymer interior block B1, where each A1 block contains essentially no sulfonic acid or sulfonate functional groups and each B1 block comprises sulfonation susceptible monomer units which are substituted sulfonamide compounds of formula (-SO2-NR1R2) (I) or their salts and the B1 block comprises 10-100 mol.% of the functional group, based on the number of the sulfonation susceptible monomer units.    Either R1 = -(A1-NR1a)xR1b or -(A1-NR1a)y-A2-Z; and    R2 = H, alkyl or R1; or    NR1R2 = 5-7-membered ring (optionally substituted and consisting of 1-3 N, 2-6 C, and optionally 1 or 2 non-adjacent O and/or S ring atoms);    x = 0-3;    y = 1 or 2;    A1, A2 = straight chain alkylene (optionally substituted by at least one CH3 and/or ethyl); and    R1a, R1b = H or alkyl; and    Z = CO2H, -SO3H or -P(O)(OH)3.    INDEPENDENT CLAIMS are also included for:    (1) a membrane or film comprising the modified sulfonated block copolymer;    (2) an electro-deionization assembly comprising at least one anode, at least one cathode, and the at least one membrane; and    (3) a coated article comprising a substrate and a coating containing the modified sulfonated block copolymer.