Amine, Melamine, and Amide N-Halamines as Antimicrobial Additives for Polymers.

N-chloro-2,2,6,6-tetramethyl-4-piperidinol laurate (Cl-TMPL) was prepared by reacting 2,2,6,6-tetramethyl-4-piperidinol hydrochloride (TMP·HCl) with lauroyl chloride, followed by chlorination with sodium dichloroisocyanurate. The chemical structure of Cl-TMPL was characterized with FT-IR, NMR, DSC, and TGA analyses. The antimicrobial performance of Cl-TMPL against Gram-positive and Gram-negative bacteria was compared with 1-chloro-3-dodecyl-5,5-dimethylhydantoin (Cl-DDMH), a amide N-halamine, and chloro-2,4-diamino-6-dodecyl-1,3,5-triazine (Cl-DADT), a melamine (imino) N-halamine. The three classes of N-halamines were used as additives for polyurethane (PU). Visible light transparency data indicated that up to 6% of Cl-DDMH or Cl-DADT could be compatibly mixed with PU, but Cl-TMPL had low compatibility with PU at higher than 2% of Cl-TMPL. With the same additive content, Cl-DDMH and Cl-DADT provided more powerful antimicrobial and biofilm-controlling effects than Cl-TMPL. In stability studies, however, PU samples with Cl-TMPL released the lowest amount of active chlorine into the immersing solution, suggesting the highest stability of the antimicrobial and biofilm-controlling efficacy.