Optimization and characterization of high-performance superhydrophobic epoxy/PTFE/CNT hybrid nanocomposite coatings

This study aims to comprehensively investigate the synergistic interaction between polytetrafluoroethylene (PTFE) and carbon nanotubes (CNT) in an epoxy matrix. The Response Surface Methodology (RSM) with a Central Composite Design (CCD) was employed for optimization of the coatings, such as water contact angle (WCA), surface roughness, hardness, and adhesion strength. The FE-SEM (field emission-scanning electron microscopy) revealed a uniformly distributed hierarchical roughness architecture resulting from the successful encapsulation of CNTs by PTFE particles. Extreme superhydrophobic coatings with the highest WCA of 151.56° were achieved at a composition of 40 wt% PTFE and 2 wt% CNT. Multi-objective optimization yielded an optimal formulation of 40 wt% PTFE and 0.7089 wt% CNT with desirability of 0.887, which was validated to produce a high WCA (139.11°), surface roughness (4.945 μm), as well as superior hardness (73.550 HD) and adhesion strength (8.685 MPa) values. This work provides a quantified optimization model with high predictive accuracy and confirms that CNT functions as an internal reinforcing network that enhances adhesion only when combined with PTFE. These findings offer fundamental insights into the mechanism of SHP topography stabilization, paving the way for the design of the next generation of tough, multifunctional, and long-term stable superhydrophobic coatings.