Antimicrobial copolymers of hydrophobic N-alkyl and benzophenone containing polyethylenimines were synthesized from commercially available linear poly(2-ethyl-2-oxazoline), and covalently attached to surfaces of synthetic polymers, cotton, and modified silicon oxide using mild photo-cross-linking. Specifically, these polymers were applied to polypropylene, poly(vinyl chloride), polyethylene, cotton, and alkyl-coated oxide surfaces using solution casting or spray coating and then covalently cross-linked rendering permanent, nonleaching antimicrobial surfaces. The photochemical grafting of pendant benzophenones allows immobilization to any surface that contains a C–H bond. Incubating the modified materials with either Staphylococcus aureus or Escherichia coli demonstrated that the modified surfaces had substantial antimicrobial capacity against both Gram-positive and Gram-negative bacteria (>98% microbial death).Keywords: antibacterial; antifouling; antimicrobial; photo-cross-linker; polyethylenimine;