Tuning the nanoscale tribological characteristics of thermally evaporated transparent polyaniline-graphene nanocomposite thin films

In this work, we report the development of a solvent-free technique to fabricate optically transparent polyaniline (PANI)-graphene thin films with precise control over both composition and thickness. By systematically varying the PANI-graphene composition, we investigate the influence of graphene reinforcement on the mechanical and tribological properties of the polymer films. A comprehensive suite of surface characterization techniques, combined with atomic force microscopy (AFM) based nanotribological testing, reveals how embedded graphene patches act as lubricating agents within the polymer matrix. More specifically, the study shows how the friction force and the coefficient of friction (COF) vary on the surface of the polyaniline-graphene composite film with the variation of graphene percentage. These findings provide crucial insights into the interfacial behavior of PANI-graphene nanocomposites and highlight the potential of such materials for next-generation applications where tailored frictional and mechanical performance is essential. This study bridges the gap between material design and practical performance, contributing to the advancement of nanocomposite thin film technologies for diverse applications.

Surface chemistry of graphene and graphene oxide: A versatile route for their dispersion and tribological applications

Graphene, the most promising material of the decade, has attracted immense interest in a diversified range of applications. The weak van der Waals interaction between adjacent atomic-thick lamellae, excellent mechanical strength, remarkable thermal conductivity, and high surface area, make graphene a potential candidate for tribological applications. However, the use of graphene as an additive to liquid lubricants has been a major challenge because of poor dispersibility. Herein, a thorough review is presented on preparation, structural models, chemical functionalization, and dispersibility of graphene, graphene oxide, chemically-functionalized graphene, and graphene-derived nanocomposites. The graphene-based materials as additives to water and lubricating oils improved the lubrication properties by reducing the friction, protecting the contact interfaces against the wear, dissipating the heat from tribo-interfaces, and mitigating the corrosion by forming the protecting thin film. The dispersion stability, structural features, and dosage of graphene-based dispersoids, along with contact geometry, play important roles and govern the tribological properties. The chemistry of lubricated surfaces is critically reviewed by emphasizing the graphene-based thin film formation under the tribo-stress, which minimizes the wear. The comprehensive review provides variable approaches for the development of high-performance lubricant systems and accentuates the lubrication mechanisms by highlighting the role of graphene-based materials for enhancement of tribological properties.

Fabrication of Eco-Friendly Solid-State Symmetric Ultracapacitor Device Based on Co-Doped PANI/GO Composite

An eco-friendly solid-state symmetric ultracapacitor (Uc) device was fabricated using a polyaniline graphene oxide composite co-doped with sulfuric acid (H₂SO₄) and dodecyl benzene sulfonic acid (DBSA) or camphor sulfonic acid (CSA), as electrode material utilizing gold sheets as current collectors. The device showed specific capacitance value of 150 F/g at 1 A/g current density, with a capacitance retention value of 93.33% at higher current density (10 A/g), indicating a high rate capability. An energy density of 15.30 Whkg⁻¹ with a power density of 1716 Wkg⁻¹ was obtained at the current density of 1 A/g. The values of areal capacitance, power density, and energy density, achieved at the current density of 5 mAcm⁻², were 97.38 mFcm⁻², 9.93 mWhcm⁻², and 1.1 Wcm⁻², respectively. Additionally, the device showed very low solution and charge transfer resistance (0.885 Ω and 0.475 Ω, respectively). A device was also fabricated utilizing copper as current collector; however, a lower value of specific capacitance (82 F/g) was observed in this case.