Deeper Insights Into Ultrasonication‐Induced Crystalline Order, Electrochemical Response, Solubility, and Thermal Resilience of Polyaniline

Polyaniline (PANI) is the most widely explored conducting polymer known for its tunable electrical conductivity, environmental stability, and ease of synthesis. However, low crystallinity, limited solubility, and inconsistencies in reported thermal stability of PANI require comprehensive investigation. Present work reports the role of ultrasonication during synthesis of PANI in improving structural order and cyclic voltametric characteristics. Crystallinity increases by 10% with an optimum sonication time of 15 min. For the first time, components of the Hansen solubility parameter of PANI are estimated, yielding an overall solubility parameter of δ = 22.3 MPa 0.5 . Further, thermal stability of PANI has been studied using in situ variable temperature powder X‐ray diffractometer (VT‐PXRD) at different heating regimes. The cyclic heating study indicates that PANI remains stable up to 100°C, beyond which the first stage of degradation initiates through crystal melting and deprotonation—a slow, reversible process continuing till 200°C. In the second stage (above 200°C), degradation accelerates with simultaneous carbonization, leading to irreversible loss of functionality. VT‐PXRD analysis in continuous and stepwise heating regimes demonstrates the susceptibility of PANI to faster degradation under sudden thermal stress compared to stepwise heating. This work provides new insights into optimizing structural order, solubility, and thermal resilience.