NOVELTY - An amino- or phosphino-functionalized block copolymer comprises at least two end blocks (A), where each end block (A) is substantially free of amino- or phosphino-functional groups and has number average molecular weight of 1000-60000 and high working temperature, and at least one interior block (D) having number average molecular weight of 1000-100000 and comprising at least one amino- or phosphino-functionalized polymer unit (I).    USE - Amino- or phosphino-functionalized block copolymer is used for forming membrane/film for apparatus e.g. fuel cell, filtration device, device for controlling humidity, device for forward electro-dialysis, device for reverse electrodialysis, device for pressure retarded osmosis, device for forward osmosis, device for reverse osmosis, device for selectively adding water, device for selectively removing water, device for capacitive deionization, device for molecular filtration, device for removing salt from water, device for treating produced water from hydraulic fracturing applications, device for ion transport applications, device for softening water and battery, and electro-deionization assembly e.g. desalination cell (all claimed). Uses include but are not limited to protective clothing, laminated fabric for protection with respect to wind, rain, snow, chemical agent and biological agent, gas-separation material, and humidity sensor.    ADVANTAGE - The amino- or phosphino-functionalized block copolymer has high anion-exchange properties. The film formed using the copolymer has high mechanical integrity, dimensional stability, and antibacterial, antiviral and antimicrobial properties.    DETAILED DESCRIPTION - An amino- or phosphino-functionalized block copolymer comprises at least two end blocks (A), where each end block (A) is substantially free of amino- or phosphino-functional groups and has number average molecular weight of 1000-60000 and high working temperature, and at least one interior block (D) having number average molecular weight of 1000-100000 and comprising at least one amino- or phosphino-functionalized polymer unit of formula (I).    Z=nitrogen or phosphorus;    R1=H or alkyl;    R=H or is tertiary alkyl optionally substituted by group of formula: -(A1-NRa)xRb;    or two R+Z=optionally substituted ring;    x=1-3;    A1=linear alkylene optionally substituted by methyl and/or ethyl;and    Ra,Rb=H, alkyl or corresponding onium salt.    INDEPENDENT CLAIMS are included for the following:    (1) electro-deionization assembly, which comprises anode(s), cathode(s), and membrane(s);    (2) selectively halogenated block copolymer, which comprises at least two end blocks (A), where each end block (A) is essentially non-halogenated and has number average molecular weight of 1000-60000 and has high working temperature, and at least one interior block (Dasterisk) having number average weight of 1000-100000 and comprising at least one polymer unit of formula (II); and    (3) precursor block copolymer, which comprises at least two end blocks (A), where each end block (A) is substantially resistant to halogenation and has number average molecular weight of 1000-60000 and has high working temperature, and at least one interior block (D0) having number average weight of 1000-100000 and comprising at least one polymer unit of formula (III).    Y'=halo.