COPOLYMER HAVING FUNCTIONAL GROUP AS SUBSTITUENT AT CHAIN-END, METHOD FOR PREPARING ELECTROLYTE MEMBRANE FOR SECONDARY BATTERY INCLUDING THE SAME, AND ELECTROLYTE MEMBRANE FOR SECONDARY BATTERY INCLUDING THE SAME

Disclosed is a copolymer as PAES-g-PEG or PAEK-g-PEG as an arylene-based polymer having ion conductivity and mechanical strength and having a functional group as a substituent at a chain-end of PEG, wherein the functional group includes one selected from a group consisting of a hydroxyl group (—OH), methacrylate (-MA), a double hydroxyl group (-2OH), a nitrile group (—CN) and an ionic liquid group (-PYRTFSI). Further, disclosed is a solid electrolyte membrane for a secondary battery including the copolymer and thus having improved ion conductivity, lithium ion transport ability, and excellent mechanical strength.