Biocidal Polystyrene Beads. III. Comparison of N-halamine and Quat Functional Groups Y. Chen, 1 S. D. Worley, 1 T. S. Huang, 2 J. Weese, 2 J. Kim, 3 C.-I. Wei, 4 J. F. Williams 5 1 Department of Chemistry, Auburn University, Auburn, Alabama 36849 2 Department of Nutrition and Food Science, Auburn University, Auburn, Alabama 36849 3 Korea Atomic Energy Research Institute, 150, Duckjin-dong, Yuseong-Gu, Daejeon, 305-353, Korea 4 Department of Nutritional Sciences, Oklahoma State University, Stillwater, Oklahoma 74078 5 Vanson-HaloSource Corporation, Redmond, Washington 98052 Received 21 August 2003; accepted 8 November 2003 ABSTRACT: A comparison has been made between the biocidal efficacies of N-chlorinated polymeric beads and two derivatives of polyquat beads. Biocidal effects were mea- sured after brief contact exposures of aqueous suspensions of either Staphylococcus aureus or Escherichia coli to the water- insoluble beads. The polymeric backbone was held the same in all three types of beads, so they differed only in their biocidal derivative moieties. In all cases, functionalization of crosslinked chloromethylated polystyrene beads was per- formed to introduce the biocidal properties. Synthetic meth- ods and test data will be presented. The most effective biocide, as measured by degree of inactivation in the short- est contact time of the two species of bacteria, was the N-chlorinated hydantoinyl derivative of methylated poly- styrene. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 363–367, 2004 Key words: biocidal polymers; N-halamine polymers; poly- quats INTRODUCTION The most widely employed biocidal materials in use today in disinfecting household products are quater- nary ammonium salt derivatives (quats) and their polymeric derivatives (polyquats). It is thought that the mechanism of action of quats and polyquats against pathogenic microorganisms involves first the adsorption of the positively charged site of the mole- cule onto the cell wall. This is then followed by diffu- sion through the cell wall to bind with and disrupt the cytoplasmic membrane, and then release of alkyl cat- ions and constituents of the cytoplasmic membrane, causing death of the cell. 1 These materials have several advantages which have escalated their use and popu- larity in society. They are generally stable in aqueous solution for extended periods and have long shelf lives. If properly designed with structures containing satisfactory lipophilic alkyl groups, such as dodecyl, they can be effective against a broad spectrum of pathogenic microorganisms. Most important, many of them have received approval by the government-reg- ulatory agencies for commercial sales. However, they also have limitations. Contact times for disinfection tend to be lengthy, and they cannot be regenerated once lost from a surface. The interested reader is referred to recent extensive reviews of quats and polyquats as biocidal materials 1,2 and an exhaustive patent literature. 3 A relatively new type of biocide, which will soon be in use in the public sector, is the heterocyclic N-halamine. Molecules representative of this type of biocide contain either nitrogen– chlorine or nitrogen– bromine covalent chemical bonds. They may be pre- pared either as water-soluble monomers 4 or as water- insoluble polymers. 2 If derivatized with electron-do- nating alkyl groups adjacent to the nitrogen(s) on the heterocyclic rings, the molecules will be very stable toward release of free halogen into aqueous solution and function as biocides by the direct contact of the cells of microorganisms with the halogen atom. Fol- lowing transfer of the oxidative halogen atom to the cell, inactivation most probably proceeds by an oxida- tion mechanism, as is presumed to be the case with free available halogen (e.g., as in hypochlorite bleach). Advantages inherent in the N-halamines as biocides are the capability of regeneration following loss of the halogen by simply exposing the molecules to addi- tional free halogen, and, in general, more rapid inac- tivation of a broad spectrum of pathogens than is the case for quats and polyquats because oxidative chlo- rine and bromine are potent biocides. Their primary limitation is that being relatively new, some regula- tory hurdles remain to be surmounted. Correspondence to: S. D. Worley (worlesd@auburn.edu). Contract grant sponsor: U.S. Air Force; contract grant number: F08637-02-C-7020. Contract grant sponsor: Vanson-HaloSource Corp. Journal of Applied Polymer Science, Vol. 92, 363–367 (2004) © 2004 Wiley Periodicals, Inc.