Hybrid nanocomposite silicone epoxy coatings: Balancing surface hydrophobicity with thermal and electrical performance

Achieving dropwise condensation in energy systems necessitates surfaces that are simultaneously hydrophobic, thermally conductive, and mechanically stable. A key challenge is that improving surface wettability often compromises both heat transfer performance and structural integrity. Consequently, most previous studies have focused on enhancing either surface wettability or bulk thermal conductivity in isolation, leaving the combined effects of mixed filler systems uninvestigated. To address this gap, a series of silicone epoxy-based nanocomposite coatings are developed utilizing a three-component system: a hydrophobic additive, graphene nanoplates (GNPs) for thermal conductivity, and fumed silica (FSiO 2 ) to synergistically enhance hydrophobicity via increased surface roughness. The coatings were characterized for wettability, morphology, thermal conductivity, and thermomechanical performance. The results demonstrate that hydrophobicity is driven by nanoparticle migration and roughness, while thermal conductivity hinges on GNP dispersion. The optimized formulation, known as SE/5B/0.2GNPs, successfully achieved the desired synergy. This composite exhibited strong hydrophobicity (contact angle = 96.2°), which is essential for facilitating efficient dropwise condensation. Additionally, it demonstrated the highest thermal conductivity (K = 0.2809 W/m⋅K) among the series, thereby minimizing thermal resistance. Furthermore, the appropriate filler ratios ensured robust mechanical properties, evidenced by suitable storage modulus (E′) and glass transition temperature (Tg), both critical for the longevity of the coating in operational environments. This balance clearly addresses the core performance goals-enhanced heat transfer through dropwise condensation without significant thermal insulation or premature mechanical failure.