Effects of Fabrication Parameters on the Mechanical and Sensing Properties of Molecularly Imprinted Polymers (MIPs) for the Detection of Per- and Polyfluoroalkyl Substances (PFAS)

Molecularly imprinted polymers (MIPs) function as synthetic analogues of antibody-antigen systems that provide molecular recognition. In combination with an electrochemical interface, MIPs afford a promising route to selectively detect a diverse range of chemical analytes and environmental contaminants (e.g., per- and polyfluoroalkyl substances, PFAS). However, mechanical instabilities and binding irreversibility may limit the practical utility as a field-deployable sensor. Herein, we present a directed optimization of MIP-based sensors for PFAS by varying key fabrication parameters (i.e., potential window, scan rate, molar ratio) to modulate the mechanical properties and sensing reversibility, as measured by atomic force microscopy (AFM)-based nanoindentation and electrochemical methods. We demonstrate that the elastic recovery of MIP films strongly depends on the synthesis scan rate during anodic electrochemical polymerization. Furthermore, the increase in the elastic recovery significantly improves the sensing reversibility and mitigates signal drift. We anticipate that understanding the synthesis parameters and mechanical properties of MIPs will provide insights into the development of robust and reliable sensors for environmental monitoring.