D-optimal optimization of photothermal polyurethane hybrid coatings for durable low ice adhesion performance

This study presents a statistical optimization of polyurethane (PU) hybrid coatings designed to reconcile the trade-off between mechanical durability, low ice adhesion, and invistigate photothermal properties of coating. A D-optimal experimental design based on Response Surface Methodology (RSM), to ensure statistical validity, was employed, comprising 18 distinct runs. This approach was used to investigate the dominant factors governing key coating characteristics, including surface wettability, roughness, mechanical and photothermal properties, ice formation temperature, and ice adhesion strength (IAS). These responses were evaluated by comparing two different architectures of amphiphilic PEG/PDMS copolymers (linear vs. graft) and adjusting the concentration of silicone oil-coated Fe₃O₄ nanoparticles. The RSM analysis revealed that copolymer content is the dominant factor driving wettability and passive anti-icing behavior, with the linear triblock PEG-b-PDMS-b-PEG copolymer (DBE-C25, 40% siloxane content) demonstrating superior surface segregation compared to the graft poly(dimethylsiloxane-graft-PEG) copolymer (CMS-626, 35% siloxane content) and nanoparticle content was identified as the dominant factor for photothermal response and surface roughness. A significant Copolymer × Nanoparticle interaction (AB) was identified for mechanical properties. The copolymer phase buffers the rigid Fe₃O₄ particles within the PU matrix and mitigates embrittlement. The same AB interaction was not significant for ice nucleation temperature, indicating that the two additives suppress nucleation through independent mechanisms.To validate synergistic de-icing potential, we developed a dynamic photothermal-inclined plane test. The optimized formulation (7.5 wt% linear copolymer, 5 wt% nanoparticles) successfully reconciled the trade-off between mechanical durability, ultra-low ice adhesion, and rapid photothermal response. It maintained robust mechanical integrity while delivering an ultra-low IAS of 17 ± 7 kPa in push-off and 78.6 ± 17.5 kPa in centrifugal tests and a rapid thermal response of 8.6 °C/min. This synergistic combination enabled the rapid shedding of 3 mm ice layers in just 12 ± 3 min at −5 °C under 1 sun irradiation. Furthermore, a 50-cycle icing/de-icing durability analysis at −10 °C confirmed the coating's long-term operational stability. The optimized hybrid degraded at a negligible rate of 0.22 kPa/cycle and sustained a 50-cycle mean IAS of 21 kPa. These results demonstrate that the optimized hybrid coating retains low ice adhesion over 50 icing/deicing cycles under the tested conditions.