Biophysicochemical characterization and biofouling growth analysis of polymer-based coating materials on fiber reinforced polymer composites

Biofouling refers to the undesirable accumulation of marine organisms on submerged surfaces and presents significant operational and economic challenges in marine-related industries. Conventional antifouling coatings such as heavy metal–based paints are effective in preventing organism attachment due to their biocidal properties. However, they release toxic substances into marine environments, contributing to ecological degradation and long-term environmental risks. As a sustainable alternative, polymer-based coatings including polytetrafluoroethylene (PTFE), polyether sulfone (PES), and polyvinylidene fluoride (PVDF) were investigated to evaluate their antifouling performance on fiber-reinforced polymer (FRP) composites fabricated with basalt and glass fibers. These coatings mitigate biofouling through surface modification rather than toxic chemical release. The study employed microbiological analysis, toxicity testing, surface characterization, and marine field exposure to evaluate performance. Heavy metal content in the coatings was identified using handheld X-ray Fluorescence (XRF). Antibacterial activity was assessed using the Kirby–Bauer disc diffusion method, while toxicity effects were evaluated using the brine shrimp lethality test. Surface roughness was measured using an Alicona surface profiler, and wettability was determined through contact angle analysis. Samples were submerged in a marine environment at Pulau Tuba, Langkawi, Malaysia, for up to 120 days, and biofouling growth was quantified using physical observation and ImageJ analysis. Results showed that KOSSAN antifouling paint demonstrated the lowest biofouling growth percentage at 10.4%, attributed to its heavy metal biocidal mechanism. However, its environmental toxicity and requirement for periodic reapplication limit its long-term sustainability. Among the polymer-based coatings, Basalt Twill Weave (Basalt TW) reinforced with PTFE exhibited the best antifouling performance among the sustainable alternatives, recording a biofouling growth percentage of 24.8%. The superior performance is attributed to the synergistic effect between high surface hydrophobicity (contact angle = 130.7°) and low surface roughness (Ra = 1.5106 µm), which together reduce organism adhesion and promote fouling-release behavior. This clarification avoids the misconception that higher roughness alone improves performance and instead emphasizes the interaction between wettability and controlled surface texture. PES and PVDF exhibited moderate antifouling resistance due to their relatively hydrophilic behavior and higher surface energy, which facilitated greater organism attachment compared to PTFE-based systems. Overall, although heavy metal–based paint showed superior antifouling efficiency with lower biofouling growth (10.4%), Basalt TW–PTFE provides the most balanced solution among polymer-based coatings by integrating reasonable antifouling performance (24.8%) with improved environmental sustainability. The findings highlight the importance of surface wettability and roughness interaction in biofouling mitigation and contribute to sustainable antifouling development aligned with Sustainable Development Goals (SDGs) 9, 12, and 14.