One-pot Synthesis of Fully Biobased Polyureas with Excellent Mechanical Properties from Epoxidized Soybean Oil

Suffered from the highly flexible structure, polymers based on epoxidized soybean oil (ESO) generally exhibit poor mechanical properties. This work aims at improving the mechanical properties by incorporating urea-bond into the backbone of such polymers. Polyureas (PUr) were designed and prepared successfully via a one-pot strategy, from urea, 1,10-decanediamine (DDA) and ESO. In this one-pot strategy, urea first reacted with DDA to form oligourea which would then polymerize with ESO. The content of urea function can be adjusted by simply changing the feeding ratio of urea/DDA and epoxy/ureido, which is to tune the mechanical properties of the obtained PUr. Compared with the two-pot synthetic method in which ESO was polymerized with 1,10-decylene bisurea (DBU), the thermal and mechanical properties of the one-pot PUr are comparable. When keeping the equal amount of ureido and epoxy groups but changing the feeding ratio of urea/DDA from 2:1 to 3:2 and even to 4:3, the glass transition temperature of PUr increases from 26.9 to 56.4 °C, as detected by dynamic mechanical thermal analysis. And the tensile strength increases from 8.2 to 17.7 MPa while the elongation at break declines from 430% to 180%. The one-pot synthetic strategy towards PUr, which is developed in this work, is promising in the construction of high performance vegetable oil-based sustainable polymers.