Thermo-Mechanical and Antibacterial Properties of Soybean Oil-Based Cationic Polyurethane Coatings: Effects of Amine Ratio and Degree of Crosslinking

Soybean‐oil‐based cationic polyurethane coatings with antibacterial properties have been prepared with a range of different molar ratios of hydroxyl groups from an amine diol. A second series of polyurethane coatings were prepared from soy polyols with different hydroxyl numbers. All of the cationic PU dispersions and films exhibit inhibitory activity against three foodborne pathogens: Salmonella enterica ssp. enterica ser. Typhimurium, Listeria monocytogenes, and Staphylococcus aureus. It is generally observed that increases in the ratio of ammonium cations improve the antibacterial performance. Reduction of the crosslink density by decreasing the hydroxyl number of the soy polyol also results in slightly improved antibacterial properties. Higher glass transition temperatures and improved mechanical properties are observed with corresponding increases in the molar ratios of the amine diol and the diisocyanate. These results show that the mechanical properties of these coatings can be tuned, while maintaining good antibacterial activity. The antibacterial activity of soybean oil‐based cationic polyurethane coatings against foodborne pathogens increases with higher ratios of ammonium cations and with lower polymer cross‐link densities. The mechanical properties of the polyurethane coatings can be adjusted, while maintaining antibacterial activity.