Polyhexahydrotriazine

They are among the strongest known thermosetting plastics and are stable to solvents at pH > 3, but decompose to the monomers in acidic solutions.

Various PHTs have been synthesized at room temperature in one step in the early 2000s; they were considered impractical due to their poor mechanical properties.

[3][4] When low heat was applied to the beaker of paraformaldehyde and 4,4ʹ-oxydianiline, it had created a hemiaminal dynamic covalent network (HDCN).

This PHT has a Young's modulus exceeding 10 GPa, which is among the highest for a thermosetting plastic; it can be further increased by ~50% by dispersing carbon nanotubes in the polymer.

[2] A number of industries could benefit from the use of PHT in manufacturing parts and devices due to its recyclability, lightweight structure, and strength:[6]

Room-temperature synthesis of polyhexahydrotriazines [ 1 ]
Polycondensation of 4,4'-oxydianiline and paraformaldehyde . At low temperatures, a hemiaminal dynamic covalent network is formed, which is plasticized with ~27% N -methyl pyrrolidone (NMP) and water. Heating to higher temperatures yields a polyhexahydrotriazine. [ 2 ]