Encapsulation films: Investigation into the degradation mechanism of multicomponent bio-based waterborne polyurethane in natural environments

In this study, the impact of different ratios of castor oil (CO) and polycarbonate diol (PCDL) mixed soft segments, as well as the introduction of sodium 2-[(2-aminoethyl)amino]ethanesulphonate (AAS-Na) salt, on the biodegradable waterborne polyurethane (WPU) was investigated. Firstly, various waterborne polyurethanes with different mixed soft segments were prepared by adjusting the ratios of castor oil and polycarbonate diol. Subsequently, varying amounts of AAS-Na salt were introduced to assess their influence on the polymer properties. The results indicated that the ratio of CO to PCDL significantly affected the mechanical properties and biodegradability of WPU. As the ratio decreased from 10:0 to 6:4, the tensile strength of WPU films decreased from 18 MPa to 11 MPa, while the elongation at break increased from 56 % to 258 %. Furthermore, the addition of AAS salt improved the water absorption and biodegradation rate of the material. When the ratio of CO to PCDL within the system is 10:0 and the molar content of AAS-Na is 20 mol%, the sample exhibits optimal water absorption of 132.12 % after 48 h and biodegradability of 30.58 % after 28 days. The degradation mechanism was preliminarily explored using Fourier-transform infrared spectroscopy. In conclusion, by adjusting the ratios of castor oil, polycarbonate diol, and AAS salt, a series of biodegradable waterborne polyurethanes with excellent performance were obtained. This study demonstrates the feasibility of developing biodegradable packaging materials using bio-based waterborne polyurethanes as the main component.