Iodine-Based Chemical Polymerization Enables the Development of Neat Amorphous Porous Organic Polymers

Amorphous porous organic polymers (POPs), with high porosity and high chemical and thermal stability, have been investigated for various applications. Most amorphous POPs are synthesized by electropolymerization or chemical polymerization. However, nonhomogeneous film formation in electropolymerization and residual metal-derived impurities in chemical polymerization are challenges. This study developed a novel chemical polymerization method for amorphous POPs using iodine as an oxidant. Specifically, we synthesized a representative amorphous POP, polytriphenylamine (pTPA). The pTPA was obtained as a powder through solution polymerization and as a thin film via vapor-assisted polymerization. Postreaction, ethanol was used to remove iodine completely. Notably, even though pTPA was constructed from rigid structures, the nitrogen-induced gate-opening phenomenon was exhibited for the first time as amorphous POPs. These results demonstrate that impurity-free amorphous POPs exhibit inherent flexibility against their rigid chemical structure. The novel iodine-based chemical polymerization enables us to synthesize neat amorphous POPs and to explore their pure functions.