Quaternary ammonium compounds are some of the most widely used antimicrobial agents for various medical applications due to their low toxicity and broad spectrum antimicrobial activity. Various generations of poly(ethyleneglycol)diacrylate (PEGDA) based dendrimers were synthesized by Michael addition reaction of PEGDA with ethylene diamine and diethyl amine. The percentage yield of different generation of dendrimers were 70%, 66%, 60%, and 85% for G1.0 (=), G1.5 (NH2), G2.0 (=), and G2.5 (=, NEt2), respectively. Synthesized dendrimers were also copolymerized with ethyleneglycol dimethacrylate by free radical bulk polymerization at room temperature using ammonium persulphate/N,N,N',N'-tetramethyl ethylenediamine as a redox initiator system to form dendritic copolymer networks. These networks were quaternized with hydrochloric acid by continuously refluxing at 40 degrees C for 6 h. Dendrimers and quaternized dendritic copolymer networks were characterized by (HNMR)-H-1, FTIR, Differential scanning calorimetry, Thermogravimetric analysis, Scanning electron microscope, swelling, and leaching studies. Synthesized quaternary ammonium dendritic copolymer networks were found to be biostable and insoluble in water and capable of killing both Gram-positive and Gram-negative bacteria when contaminated water was treated with them. It was also observed that antimicrobial efficiency of dendritic copolymer networks increases with the increase in nitrogen atoms in the copolymer. The dendritic copolymer network with 16 quaternary ammonium groups (G2.5 (=, NEt2): EGDMA QHCl) were highly efficient to disinfect 10 mL bacterial solution of 2000 cfu/mL within 2 min even at a very low concentration of 0.005 g/mL. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 116: 1640-1649, 2010