Self-healable, weldable, and reprocessable castor oil-based poly(thiourethane-urethane) networks

Vegetable oil-based polyurethane (PU) vitrimer is of significance for sustainable industrial development; however, development of vegetable oil-based PU vitrimers with high mechanical properties and excellent malleability by a facile synthetic process remains a challenge. Herein, a series of versatile, self-healable, weldable, and recyclable castor oil-based poly(thiourethane-urethane) networks are constructed by one-pot reactions. Double bonds and hydroxy groups in castor oil can react with thiol in 2,2′-(1,4-phenylene)-bis[4-mercaptan-1,3,2-dioxaborolane] (BDB) and isocyanate in 4,4′-diphenylmethane diisocyanate (MDI), respectively, as well as a reaction between the thiol of BDB and the isocyanate of MDI, which gives the castor oil-based poly(thiourethane-urethane) vitrimers. The obtained bio-based networks are characterized by Fourier transform infrared (FTIR) and dynamic mechanical analysis (DMA) measurements. The castor oil-based vitrimers show high thermostability ( T 5d > 312°C) due to the incorporation of rigid BDB and MDI with benzene group in the networks. Meanwhile, the castor oil-based networks have been proved to possess more excellent functions in self-healing, welding, shape memory, and reprocessing capabilities at moderate temperatures due to the dynamic boronic ester bonds. This work would be beneficial to developing of versatile vegetable oil-based poly(thiourethane-urethane) materials through a facile approach.