The swelling behavior and dye sorption of polystyrene-graft-poly(N,N-dimethylamino-2-ethyl methacrylate (pseudohydrogel) have been investigated. The grafting of N,N-dimethylamino-2-ethyl methacrylate (DMAEMA) onto the molecular surface of polystyrene through the "grafting from" approach is performed at room temperature ATRP, resulting in pseudo-hydrogels. The swelling behavior of these hydrogel at different pH and by varying the chain length of DMAEMA was carried out. The effect of altering pH and the temperature towards the swelling is also studied. The dimensional change, caused by the stimulus behavior of the hydrogel, at varying pH is also investigated. The stimulus responsive graft copolymer was studied for the adsorption of common dyes like green torquoise blue, magenta red, rhodamine, crystal violet, congo red, methylene blue, under static condition at room temperature. The graft copolymers are observed to possess a high affinity for basic, acid, and reactive dyes. (C) 2008 Elsevier Ltd. All rights reserved.