there are disclosed ph - sensitive polymers containing sulfonamide groups , which can be changed in physical properties , such as swellability and solubility , depending on ph and which can be applied for a drug - delivery system , bio - material , sensor , etc , and a preparation method therefor . the ph - sensitive polymers are prepared by introduction of sulfonamide groups , various in pka , to hydrophilic groups of polymers either through coupling to the hydrophilic groups , such as acrylamide , n , n - dimethylacrylamide , acrylic acid , n - isopropylacrylamide , etc , of polymers or copolymerization with other polymerizable monomers . these ph - sensitive polymers may have a structure of linear polymer , grafted copolymer , hydrogel or interpenetrating network polymer .