Eight-membered ring cyclic carbonates comprising a ring nitrogen at position 6 (1,3,6-dioxazocan-2-ones) were prepared by reaction of precursor diols with active carbonates. The ring nitrogen is linked to a pendant group Y′ via a methylene linking group. The cyclic carbonates undergo organocatalyzed ring opening polymerization to form an initial polycarbonate comprising a backbone tertiary amine group. Quaternization of the initial polycarbonates forms cationic polycarbonates comprising a positive-charged backbone quaternary nitrogen. The cationic polycarbonates can be potent antimicrobial agents.