Synthesis and antibacterial characterization of waterborne polyurethanes with gemini quaternary ammonium salt

To obtain an aqueous polymer system with good antibacterial properties, a series of gemini waterborne polyurethanes (GWPU) were designed and synthesized using isophorone diisocyanate, polyoxytetramethylene glycol, poly(ethylene glycol), L-lysine and a novel L-lysine-derivatized diamine containing gemini quaternary ammonium salt (EG12) without any other organic agent involved in the whole synthetic process. EG12 was first synthesized and characterized with proton nuclear magnetic resonance spectra and mass spectra. The antibacterial activities of EG12 and GWPU were evaluated by quantifying the minimal inhibitory concentration. The results indicated that the gemini quaternary ammonium chain extender EG12 and GWPU showed excellent antibacterial activity against a broad spectrum of gram-positive and gram-negative bacteria. This work provides a new and facile approach to prepare novel antibacterial materials, which could be applied as coatings in various fields to prevent microbial contamination.