Synergistic strengthening and toughening of the recyclable polyhexahydrotriazine (PHT) crosslinked polyimide by constructing rigid-flexible structure for tribology application

Developing sustainable thermosetting resins and their composite materials is one of the key research topics in the field of sustainable tribology today. This study prepared a series of polyhexahydrotriazine-crosslinked polyimide (PI-PHT) films featuring rigid skeleton-dynamic networks through polycondensation of amine-terminated polyimide oligomers with formaldehyde. The PI-PHT/250 °C film demonstrated outstanding tribological performance in various complex friction environments owing to its highly crosslinked rigid-flexible network, exhibiting a specific wear rate 55 % lower than conventional thermosetting polyimides (TBPI). Crucially, these high-performance films achieve complete degradation and recycling under acidic conditions (pH < 2, 25 °C). PI-PHT films and their composites uniquely combine exceptional wear resistance with recyclability, presenting significant application potential in sustainable tribology.