Lighting up Polynitrodopamine: from Electropolymerization to Photopatterning of Ultrathin Films

Polydopamine (PDA) and its derivatives, including polynitrodopamine (PNDA), have attracted considerable attention as versatile materials for surface functionalization and coating. The range of functions in PDA materials increases as new functional groups are conjugated to the dopamine monomer or as copolymers with dopamine derivatives are developed. We report the electropolymerization and photopatterning of PNDA nanofilms as well as free-standing copolymer nanofilms. The insertion of a nitro group into the dopamine structure provides enhanced film properties, including increased film density and photodegradability, thereby facilitating precise nanofilm patterning upon exposure to light. In contrast to PDA, the electropolymerization of PNDA offers to precisely control nanofilm thickness, with film thickness increasing in successive cycles from 19 to 50 nm. While the transfer of pure PNDA films to other surfaces proved challenging, the copolymerization of nitrodopamine and dopamine affords ultrathin films that could be transferred, which gives access to free-standing nanofilms. These 2D PDNA/PDA-based materials reveal photosensitivity as demonstrated through photopatterning yielding smart, customizable surfaces. These results underline the potential of PNDA in advancing surface patterning technologies, with implications for applications in biomedical devices, microfluidic, and sensors.