Pressure-Driven Solid-State Radical Polymerization toward Carbon Nanothread

Abstract

Mechanochemical radical polymerization has unique advantages in the synthesis of polymers due to its reduced solvent consumption and adaptability of insoluble monomers. However, it suffers from the uncontrollable degradation of the formed polymers during reaction, and a new synthetic strategy with precise controllability needs to be developed. Here, by employing high static pressure up to 30 GPa, we found 1,3,5-trifluorobenzene undergoes radical polymerization by breaking the conjugated π-bonds and forms a carbon nanothread with high selectivity (Polymer-I polymorph). Based on the crystal structure at the threshold pressure and the calculated energy barriers for the bonding pathway, we concluded that the benzene rings react via a radical 1,2-addition pathway. Our work highlights that high pressure is a robust method to initiate solid-state radical polymerization, even for very stable aromatics, and offers fresh insights for the synthesis of polymeric carbon-based materials with high selectivity.