Design and development of a novel polymer coating system with exceptional creep resistance

Polymer coatings often suffer from poor mechanical properties, including low strength and modulus, making them prone to creep failure under minimal loads. To address these challenges, this study introduces a novel polyurethane (PU) coating reinforced with 4 wt% hollow ceramic microspheres (HCM) coated with a TiO₂ shell (HCM@TiO₂). The modified coating exhibited a 111% increase in nanoindentation hardness, along with significant reductions in creep displacement (31%), indentation creep rate (19%), and creep strain rate sensitivity (28%) compared to the base PU. In contrast, a second additive, solid silica nanospheres with TiO₂ shells (SSN@TiO₂), did not improve mechanical performance and even increased creep displacement by 31%, likely due to polymer chain sliding. Notably, the HCM@TiO₂ coating maintained and even improved its creep resistance under higher loads. These findings suggest that HCM@TiO₂-enhanced coatings could be highly beneficial for applications requiring resistance to high-cycle creep-fatigue failure.