disclosed is a bioactive polymer comprising an effective biocidal amount of moieties derived from pyrithione and having the formula ## str1 ## wherein r 1 , r 2 and r 3 are individually selected from hydrogen and alkyl groups having from 1 to 4 carbon atoms ; and pt represents the pyrithione moiety which is defined as ## str2 ## wherein r 4 , r 5 , r 6 and r 7 are individually selected from hydrogen and , a lower alkyl group having from 1 to about 8 carbon atoms , a lower alkoxy group having from 1 to about 8 carbon atoms , a nitro group and a halo group .