High-biobased-content UV-curable oligomers derived from tung oil and citric acid: Microwave-assisted synthesis and properties

By using the bioresources of tung oil and citric acid, two novel UV-curable oligomers (TMCG1 and TMCG2) were synthesized via microwave technology and confirmed by FT-IR, H-1 NMR, and C-13 NMR. The total reaction time was only 30 min, and the obtained oligomers showed high biobased contents (over 60%). Furthermore, a series of UV-curable coatings were constructed by copolymerizing the oligomers with a biobased reactive diluent (GA) from guaiacol. The resulting UV-cured materials achieved both high biobased content and high performance. For instance, the cured TMCG1 film with 10% of GA showed a biobased content of 72.4%, tensile strength of 16.6 MPa, glass transition temperature of 74.1 degrees C, maximum thermal degradation temperature of 437.2 degrees C, adhesion of 2 grade, pencil harness of 2H, and flexibility of 2 mm. Therefore, the developed biobased oligomers show great potential to be applied in UV-curable coatings.