Multi-Objective Analysis of Electrodeposition Pathway–Dopant Coupling in Polyaniline Proton-Responsive Interfaces

Electrochemically deposited polyaniline (PANI) is widely used as a proton-responsive interface; however, the coupled influence of the electrodeposition pathway and dopant chemistry on film structure, interfacial properties, and pH-dependent electrochemical response remains insufficiently understood. Here, we systematically investigate how electrochemical growth conditions influence the structure-property relationships of PANI thin films using multi-variable experimental analysis combined with statistical and machine-learning-assisted interpretation. A systematically varied materials library was generated by combining multiple electrodeposition protocols with different acidic dopants, enabling direct comparison of morphology, interfacial behavior, and potentiometric pH response across fabrication conditions. Morphological analysis revealed that deposition pathway-dopant coupling controls film density, microstructure, and proton-accessible interfaces, producing distinct functional regimes. To quantitatively integrate competing response characteristics, normalized descriptors were combined into a multi-objective utility function, enabling systematic comparison and ranking of fabrication parameters. Machine-learning-assisted analysis indicated that the deposition pathway exerts a stronger influence on the composite performance metrics than dopant identity within the investigated design space, while dopant chemistry remained an important interacting factor. Complementary density functional theory calculations showed that optimal pH responsiveness arises from balancing electronic reactivity with chemical stability in dopant-modified PANI structures. The resulting processing-structure-function relationships provide quantitative insight into how electrochemical growth conditions influence conductive polymer interface performance. Applicability of the optimized growth strategy was demonstrated by integrating the material into a flexible textile platform for pH-responsive electrochemical operation under wearable conditions. More broadly, this work demonstrates a structured multi-objective analysis strategy for evaluating electrochemically fabricated polymer interfaces.