Understanding Degradation Dynamics of Azomethine-containing Conjugated Polymers

Understanding the influence of chemical environments on the degradation properties of conjugated polymers is an important task for the continued development of sustainable materials with potential utility in biomedical and optoelectronic applications. Azomethine-containing polymers were synthesized via palladium-catalyzed direct arylation polymerization (DArP) and used to study fundamental degradation trends upon exposure to acid. Shifts in the UV-vis absorbance spectra and the appearance/disappearance of aldehyde and imine diagnostic peaks within the ¹H NMR spectra indicate that the polymers will degrade in the presence of acid. After degradation, the aldehyde starting material was recovered in high yields and was shown to maintain structural integrity when compared with commercial starting materials. Solution-degradation studies found that rates of degradation vary from 5 h to 90 s depending on the choice of solvent or acid used for hydrolysis. Additionally, the polymer was shown to degrade in the presence of perfluoroalkyl substances (PFASs), which makes them potentially useful as PFAS-sensitive sensors. Ultimately, this research provides strategies to control the degradation kinetics of azomethine-containing polymers through the manipulation of environmental factors and guides the continued development of azomethine-based materials.