Interfacial Engineering in Polyaniline Hybrid Nanocomposites: Role of Compatibilizers and Silane-Modified Carbon Fibers in Functional and Optoelectronic Applications

Polyaniline (PANI) is a widely studied conducting polymer owing to its tunable electrical properties, environmental stability, and relatively low-cost synthesis, making it a promising material for multifunctional composite systems. This review presents a systematic analysis of PANI-based hybrid nanocomposites incorporating silane-treated short carbon fibers (SCFs), carbon nanofillers such as carbon nanotubes (CNTs) and graphene, and Maleic Anhydride (MA)-based compatibilizers. Emphasis is placed on interfacial engineering strategies that enhance dispersion, adhesion, and charge transport across multiphase systems. The role of MA-based compatibilizers in improving phase compatibility through chemical interactions and interfacial coupling is critically discussed, alongside the effect of silane surface treatment in modifying carbon fiber reactivity and promoting efficient stress transfer. The synergistic interaction between compatibilization and surface modification is analyzed in terms of its influence on electrical conductivity, mechanical performance, thermal stability, and dielectric behavior. Particular attention is given to structure–property relationships governing charge transport and interfacial polarization in hybrid nanocomposites. The review further examines recent developments in PANI-based systems for applications in sensors, energy storage devices, electromagnetic interference shielding, and optoelectronic components. From a sustainability perspective, the potential of these materials for energy-efficient devices, environmentally benign processing, and durable, multifunctional systems is highlighted, aligned with global sustainable development goals. Finally, key challenges related to interfacial complexity, scalability, and multi-component interactions are identified, and future research directions are proposed toward the rational design of high-performance, sustainable PANI-based hybrid nanocomposites.