AUTHOR=Yang Wen , Xie Yaofeng , Chen Jipeng , Huang Chunmei , Xu Yanlian , Lin Yucai 

TITLE=Metal Ion-Catalyzed Low-Temperature Curing of Urushiol-Based Polybenzoxazine

JOURNAL=Frontiers in Chemistry

VOLUME=10

YEAR=2022

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2022.879605

DOI=10.3389/fchem.2022.879605

ISSN=2296-2646

ABSTRACT=<p>In this work, urushiol-based polybenzoxazine is cured by the Lewis acid (FeCl<sub>3</sub>, AlCl<sub>3,</sub> and CuCl<sub>2</sub>) at low temperature instead of high thermal curing temperature. The effect of the Lewis acid on structures and properties of the polymers is revealed. The relating urushiol-based benzoxazine monomer (BZ) was synthesized by natural urushiol, formaldehyde, and <italic>n</italic>-octylamine. The monomer was reacted with the Lewis acid with a molar ratio of 6:1 (N<sub>monomer</sub>: N<sub>Metal</sub>) at 80°C to obtain films that can be cured at room temperature. The chemical structures of benzoxazine monomers were identified by Fourier-transform infrared spectroscopy (FTIR) and <sup>1</sup>H nuclear magnetic resonance spectroscopy (<sup>1</sup>H-NMR). The interaction between the metal ion and the polymers is revealed by X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance-FTIR (ATR-FTIR). The effect of the Lewis acid on the mechanical properties, wettability, and thermal stability was investigated. The results show that the benzoxazine cured by Cu<sup>2+</sup> has a better performance than that cured by Al<sup>3+</sup> and Fe<sup>3+</sup>.</p>