Abstract: A silane-QAC-dendritic polymer biocide surface treatment for bath, screen or spray-on application. The silane-QAC-dendritic polymer biocide generally comprises a hyperbranched polymer modified to include functionalized quaternary ammonium for biocidal activity, and further modified to include a functionalized silane moiety to covalently attach the polymer biocide to a variety of substrates through hydrolysis. The hyperbranched polymer may be any one from among a group consisting of dendrimers, dendritic polymers, and hyperbranched polymers, and the functionalized silane moiety may be Siloxane (—Si(OR)3). The resulting surface treatment combines the demonstrated high potency of quaternary ammonium compound dendrimers and hyperbranched polymers with the well-established coupling chemistry of silane functional groups. Upon hydrolysis, the silane groups will covalently attach to functional groups such as amines and hydroxyl groups.