The sterically hindered amine monomer 4[3-trieth oxysilylpropoxyl]-2,2,6,6-tetramethylpiperidine has been synthesized and covalently bonded to the surfaces of silica gel particles and cellulose (cotton) and copolymerized in a polyurethane coating formulation. Upon exposure to dilute sodium hypochlorite (household bleach), a very stable N-Cl bond is formed in situ at the hindered amine nitrogen site. This source of oxidative chlorine provides an antimicrobial function to the silica gel, cotton, and polyurethane. Stability, regenerability, and biocidal efficacy data are presented. The new N-halamine materials were remarkably effective against Staphylococcns aurens and Escherichia coli O157:H7 in brief periods of contact. The materials should find application in water treatment and medical applications. (c) 2007 Wiley Periodicals, Inc.