Enhanced Mechanical Properties And Functional Performances Of Cationic Waterborne Polyurethanes Enabled By Different Natural Phenolic Acids

Tailoring the performance of waterborne polyurethanes through composition control and structural optimization to meet the highly diversified modern demands is still one of the primary challenges faced by the polyurethane industry. Herein, various natural phenolic acids as neutralizers, for the first time, were applied for the preparation of castor oil-based cationic waterborne polyurethanes (CWPUs). The effects of these neutralizers on the microstructure (phase separation and hydrogen bond) and performance (mechanical properties, antibacterial activities, etc.) of the CWPUs were systematically investigated and compared with those of other commonly used neutralizers. The results indicate that apart from serving as neutralizers, phenolic acids also acted as antiplasticizing agents for the CWPU films by increasing the rigidity of the hard segment and hydrogen bond number. Also, the hydrophobic, rigid, conjugated structure of phenolic acids endowed the resulting CWPU films with excellent water resistance and UV protection. The introduction of phenolic acids also endowed the resulting polyurethane films with good antibacterial performance against both Gram-positive and Gram-negative bacteria. This study provides a novel and facile approach to tailor the performance of environmentally friendly cationic waterborne polyurethanes through natural phenolic acid neutralizers, along with eliminating long-standing issues of WPUs, such as irritating odor and air pollution.