Na0.67 K0.13Ca0.02Ba0.04(Si7.47Al0.53)(Al2.59Fe0.78Ti0.14Mg0.44Cr0.04)O20(OH)4

MMT possesses a high cationic-exchange capacity (CEC), which ranges between 80 and 150 meq./100 g, as well as high reactivity and a large surface area. MMT clay's crystal structure consists of nanometer-thick layers or plates (approximately 1 nm) of aluminum octahedron sheets sandwiched between two silicon tetrahedron sheets. When the layers are arranged and stacked, a gap between them is created that is known as d-spacing or gallery spacing [12,20,21]. MMT and other layered silicate clays are hydrophilic by nature. This makes them unsuitable for interacting and mixing with most hydrophobic polymer matrices. The surface of the inorganic clay should be treated with an organic surfactant to make it compatible with the organic polymer. The conventional ion-exchange method is a simple way to modify the clay surface. The most common organic surfactants used for clay modification are phosphonium or ammonium ions in the primary, secondary, tertiary, and quaternary states. Organic cations can be exchanged for inorganic cations (K+, Na+, and Ca++) that are not strongly bound to the clay surface [12–19,21–24]. This organic modification causes the d-spacing to increase in proportion to the length of the alkyl group in the surfactant. A wide range of matrix polymers are compatible with modified organic clay (OC) [12–19,21–24]. The organic polymer can diffuse into the clay galleries after reducing the electrostatic interaction between the clay layers, which helps to separate the clay platelets so they can be more easily intercalated and exfoliated. Polymer nanocomposites represent an exciting and promising alternative to conventional composites due to the dispersion of nanometer clay platelets and their improved performance in mechanical, thermal, barrier, optical, electrical, and other physical and chemical properties [8,17–19,21–26]. In the present study, proceeding from our previous findings, we aimed to enhance the coating protection of C-steel using low clay loading and two types of clay.

Because of the amount of sea salt deposited on metallic and nonmetallic bodies, the marine system is one of the most important aggressive-corrosion environments. To simulate the seawater system, the corrosion behavior of steel bodies is frequently studied in a solution containing 3.5% *w*/*v* % sodium chloride. The difference in the coating efficiency of C- steel differs according to the clay type or nanoadditive intercalated with the polymer. In the first stage, the goal of this research was to modify and prepare polystyrene/organoclay nanocomposites (PS/OC PCNs). In the second stage, we aimed to characterize these PCN

formulations using FT-IR, XRD, and TEM. The final stage was to investigate the corrosion behavior of C-steel rods coated with PCN using commercial Indian clay (CCIn) and local Khulays clay (RCKh) at various concentrations (1, 3, 5% PCN). The coating efficiency of the RCKh and CCIn after preparing the anticorrosive PCN coatings was then calculated using various electrochemical methods, such as electrochemical impedance spectroscopy (EIS), the electrochemical frequency modulation (EFM) method, and Tafel plots.

#### **2. Materials and Methods**
