Constructing the fluorine-containing structures for excellent tribological properties of degradable Poly(hexahydrotriazine)s

Abstract

Nowadays, degradable thermosets are confronted with a contradiction between their low performance and practical applications. In light of the weak covalent bonding of reversible bonds in biodegradable thermosetting resins, limits their applications in the field of tribology. Herein, we synthesize degradable poly(hexahydrotriazine)s (PHTs) by introducing trifluoromethyl (-CF₃) groups at different positions of the aromatic diamine main chains, achieving simultaneous improvement of degradability and high friction performance. The results showed that the fluorinated PHTs exhibited higher glass transition temperature (173.8 °C), tensile strength (61.8 MPa), and faster degradation rate (3 h) as compared to non-fluorinated polymer. Notably, fluorinated PHT resins exhibited excellent anti-wear performance with wear rates decreasing by 78.6 % owing to the large steric hindrance effect and strong electronegativity brought about by –CF₃, which increases the rigidity and heat resistance of the PHTs molecules, thereby enabling it to effectively resist frictional heat generated during the friction process. Fluorinated PHTs revealed excellent wear resistance and degradation properties, which facilitates their practical application of energy conservation and protective metal anti-wear coatings in the tribological industry.