Nitric Oxide (NO) Endows Arylamine-Containing Block Copolymers with Unique Photoresponsive and Switchable LCST Properties

The fabrication of materials that are responsive to endogenous gasotransmitter molecules (i.e., nitric oxide, hydrogen sulfide, and carbon monoxide) has emerged as an area of increasing research interest. In the case of nitric oxide (NO), o-phenylenediamine derivatives have traditionally been employed due to their ability to react with NO in the presence of oxygen (O2) with the formation of benzotriazole residues. Herein, we report the synthesis of a novel NO-responsive polymer containing aromatic primary amine groups derived from p-phenylenediamine groups (i.e., isomers of o-phenylenediamine). A new NO-responsive monomer, N-(4-aminophenyl)methacrylamide (p-NAPMA), was first synthesized via the amidation of one of the primary amine groups in the p-phenylenediamine with methacrylic anhydride. Notably, the p-NAPMA monomer can efficiently react with NO in aqueous solution in the presence of O2 with the generation of phenyldiazonium groups rather than benzotriazole moieties. While the resultant phenyldiazoniu...