In response to hospital acquired infections stemming from biofilms and the impending antibiotic resistance crisis, the development of non-traditional, non-leachable antimicrobials have gained significant traction. Contact-active antimicrobial coatings physically attached to surfaces with cationic active sites, such as ammonium and phosphonium, are of particular interest in the prevention of pathogenic bacterial transfer. Previously reported antimicrobial coatings are found to be susceptible to abrasion, significantly limiting their potential applications. In this work, a range of robust, antimicrobial polymeric coatings synthesized by control radical polymerization are presented. Polymeric thin film coatings possessing cationic groups with n-alkyl substituents of n ≤ 4 demonstrated antimicrobial properties against gram-positive bacteria, while species containing bulkier substituents were biologically inactive, contradictory of previously reported monomeric coatings. Cationic polymeric brush coatings were found to have a higher antibacterial activity against the gram-positive model compared to its non-brush equivalent, but failed against the gram-negative model. These polymeric thin films demonstrate the complexity of antimicrobial coating designs and facilitates the investigation into the architecture of these coatings.