One-Step Synthesis of Biodegradable Polyurethane Prepolymer and Its Rapid Gelation Behavior at High Water Content

In this study, a very simple, scalable, and low-cost one-step recipe is presented for preparing a biodegradable polyurethane prepolymer composed of isocyanate terminated linear polyethylene glycol and isocyanate terminated four-armed polycaprolactone. Then, the corresponding hydrogels are easily formed by mixing the prepolymer with water in few minutes. The resulting hydrogel shows excellent mechanical properties with high tensile strength (up to 233.6 KPa) and recorded elongation rate (5000%), while maintaining high water content (up to 91% mass ratio). Meanwhile, the maximum water retaining capacity of the hydrogel can be up to 40 times of polyurethane prepolymer (in mass), which is equal to 97.6% water content. In addition, the degradation properties of the obtained hydrogel are studied in detail. This study demonstrates a facile approach to prepare the hydrogel with both excellent mechanical properties and high water content, which marks it as a potential candidate for applications in agrological field, such as sand fixing in desertification control.