Preparation of gallic acid modified waterborne polyurethane made from bio-based polyol

Abstract WPU was prepared by a simple and bio-based method using poly(1,3-propylene glycol-adipic acid) (PPA) and isophorone diisocyanate (IPDI) as raw materials. Intriguingly, PPA can be synthesized using 1,3-propanediol which was extracted from plant stalk. Then a non-toxic, environmental-friendly gallic acid modified bio-based waterborne polyurethane (GWPU) was successfully prepared utilizing the prepolymer method with gallic acid (GA) was as a modifier. The structures, morphologies and thermostability of GWPU were confirmed by FTIR, TEM, TG, DSC and AFM. Furthermore. Its mechanical properties and water resistance were evaluated as well. The results demonstrated that self-prepared PPA has no influence on the properties of polyurethane. However, when the content of GA was increased from 0% to 3.3%, the tensile strength of GWPU film increased by 155.3% compared with that of unmodified PU film, the elongation at break decreased by 86%, and the decomposition temperature of the film increased by 23.8 °C, the surface roughness decreased by 41.0%. In addition, through the crosslinking of GA, the water resistance of GWPU is improved.