One-Pot Four-Component Synthesis of Acid-Responsive and Degradable Heterochain Polymers with Nonconventional Luminescence

The development of nonconventional luminescent heterochain polymers with unique structures and attractive stimuli-responsive degradation properties has gained great attention in recent years. In this work, a series of nonconventional luminescent heterochain polymers with diverse structures, excellent solubility, and high relative molecular weights (Mw up to 89,000 g/mol) were facilely synthesized in good yields (up to 90%) using a novel one-pot four-component polymerization tool in air at room temperature within merely 1 h. The presence of abundant C═N bonds in both the backbones and side pendants of these poly(N-sulfonylamidine)s endowed them with excellent hydrolytic degradability under acidic conditions at room temperature. The polymer could be further transformed into a well-defined poly(N-sulfonylamide) structure within 10 h. Benefiting from the heteroatom-rich characteristics, the prepared polyamidines and polyamides exhibited bright solid-state fluorescence despite the absence of conventional luminophores with large π-conjugation or the influence of aggregation-caused quenching units. The polymer solid powders generally showed excitation-dependent fluorescence due to the clusterization-triggered emission mechanism. Furthermore, the nonconventional luminescent polymer films exhibited obvious and reversible fluorescence changes in response to acid vapors, which makes them potential fluorescent sensing materials for the detection or early warning of the leakage of volatile acids.