Preparation of Polymer-Based Coatings from Bio-Based Materials

Abstract: The corrosion of steel stands as a globally recognized concern. Castor oil-based coatings emerge as formidable protective shields against corrosion, displaying strong adherence to metal surfaces and resilience against moisture, chemicals, and other corrosive agents. In the contemporary context, the pursuit of sustainable and non-hazardous coatings derived from environmentally benign substrates is a focal point of interdisciplinary research, addressing the issue with a holistic approach. In this study, Castor oil sourced from natural reservoirs undergoes transformation into epoxidized castor oil (ECO), serving as a precursor for the synthesis of bio-based coatings [1-4]. Additionally, an electroactive polyaniline (PANI), carbonized polyaniline (C-PANI), and their composite polyaniline-carbonized (PANI-CPANI) [39] variant are prepared and evaluated by incorporating them into the ECO matrix. The characterization of the polyaniline composite material is conducted using powder X-ray diffraction (powder-XRD), while morphological analysis is facilitated through scanning electron microscopy (SEM). Furthermore, the coating system's physicochemical and mechanical properties are assessed using standard techniques such as Universal Testing Machine (UTM) analysis. The presence of PA/CP in the films renders them hydrophilic, as evidenced by alterations in the water contact angle (WCA), with a notable increase of up to 20° observed. The coated hybrid film on mild steel substrates undergoes Potentiodynamic Polarization (PDP) analysis to evaluate the corrosion inhibition potential. The investigation demonstrates that the ECO PANI-CPANI [39] composite coating system exhibits superior corrosion resistance, as indicated by parameters such as corrosion current (Icorr) of 6.46x10-14A, corrosion rate (CR) of 7.86x10- 6mm/year, charge transfer resistance (Rct) of 5.04.9x106ohm, and a phase angle exceeding 80°. These eco-friendly coatings are in alignment with sustainability endeavors, offering robust protection while mitigating maintenance expenses and reducing environmental impact [30-33].