BIOCIDAL POLYMERS ACTIVE BY CONTACT .2. BIOLOGICAL EVALUATION OF POLYURETHANE COATINGS WITH PENDANT QUATERNARY AMMONIUM-SALTS

Films of polyurethane were prepared by reaction of hydroxytelechelic p olybutadienes carrying covalently bound quaternary ammonium salts with an aliphatic triisocyanate. These coatings exhibited high biocidal ac tivity against Gram-positive and Gram-negative bacteria, yeasts, and m oulds. It was found that many parameters controlled the bioactivity su ch as the time of contact between films and bacteria, the [NCO]/[OH] r atio used to prepare the cured polyurethane, the concentration of quat ernary ammonium salts in the coating, and the length of the alkyl chai n from C-8 to C-16 linked to the quaternary nitrogen atom. A secondary phenomenon of diffusion only observed with the shorter alkyl chains ( C-8 and C-10) was shown to be due to synthesis residues. After these w ater-soluble impurities are eliminated, the biocidal activity remains excellent: then it is due only to a contact polymer bacteria. (C) 1993 John Wiley & Sons, Inc.