An embodiment of the inventive concept provides a method of manufacturing a polymer film, the method including: preparing a first copolymer containing a first functional group; preparing a second copolymer containing a second functional group; preparing a first compound containing a third functional group; and performing a cross-linking reaction by mixing the first copolymer, the second copolymer, and the first compound, wherein the cross-linking reaction includes a reaction of the first functional group and the second functional group and a reaction of the second functional group and the third functional group, the first compound includes a polar group and any one group selected from among a vinyl group, an aryl group, and an acrylate group, and the third functional group has reactivity with respect to the second functional group, but does not have reactivity with respect to the first functional group.