Dual-Patterned Porous Polymer Film with Micro Trapped Charge for Reversible Molecular Detection

Abstract Hierarchically structured porous polymer films have attracted increasing attention for electrochemical sensing, biointerfaces, and advanced functional surfaces. Herein, we present a simple, machine-free, and scalable bottom-up strategy for fabricating dual-patterned polyaniline (PANI) porous films integrating ridge–valley morphologies through vapor–liquid interfacial polymerization. The fabrication process employs economical and readily accessible precursors, including benzoyl peroxide (BPO) as the oxidant and poly[(Z)-1-(tert-butyl)cyclooct-4-en-1-ol] (P2) as a flexible polymer component that significantly enhances film flexibility relative to polystyrene (PS) substrates while maintaining structural integrity. Under ambient solution-processing conditions, spontaneous pattern formation arises from the coupled effects of interfacial polymer growth, solvent evaporation, and stress relaxation, eliminating the need for lithographic patterning, templates, or external mechanical processing. Importantly, the dual-patterned porous architecture establishes a unique structure–function relationship for electroactive biomolecule interactions. The porous domains promote localized accumulation of electroactive biomolecules by serving as adsorption reservoirs, whereas the interconnected conductive ridges facilitate efficient electron-transfer pathways after desorption. Combined with the pH-responsive protonation/deprotonation behavior of PANI, this hierarchical architecture enables reversible capture, electrochemical conversion, and detection of dopamine (DA), serotonin (5-HT), and ascorbic acid (AA). The behavior is attributed to reversible modulation of local electrostatic interactions and charge distribution within the porous conductive network. As a result, the individual pores within the porous film act as localized sites for analyte accumulation, signal transduction, and molecular recognition under mild pH-switching conditions, demonstrating potential for responsive sensing applications as a smart film.