The effect of copolymerization of Hou Po-bisphenol units on cationic waterborne polyurethane

Bio-based bisphenols from Hou Po (Cortex Magnoliae Officinalis, one of the popularly used herb in traditional Chinese medicine) was applied as a new kind of the chain extender for the synthesis of cationic waterborne polyurethane (CWPU). Since the representative Hou Po-bisphenols include magnolol (MAG), honokiol (HON) and Magnolia officinalis extract (MPE), to explore their subtle structure effects and distinguish them from their petrochemical analogs of bisphenol A (BPA) and 2,2′-biphenol (OBP), the CWPU modified by different bisphenols were systematically characterized and compared. It has been found that the copolymerization of MAG onto the backbone of CWPU can give out superior film toughness, damping factors and self-healing efficiency (>90%). The elastic film recovered from the cut-off damage exhibited the tensile strength of 41.5 MPa and the elongation at break of 940%. On the contrary, MPE modified CWPU exhibited remarkable reinforcement effect on the CWPU films, and the tensile strength reached ~50 MPa but with the sacrificed reversibility. The enhanced thermal stability and surface hydrophobicity were also pronounced on the MPE modified CWPU. The very different roles of the Hou Po-bisphenols are in sharply distinctive from their petrochemical analogs, providing new insights into the design of biologically sourced materials.