目的 构建一种兼具超疏水性与光热响应能力的功能涂层,以提升其在低温环境下的除冰性能。方法 通过在碱性条件下采用共沉淀法,在蒙脱土（MMT）表面原位合成四氧化三铁（Fe3O4）纳米颗粒,并在氮气气氛下反应以防止亚铁氧化,随后引入十八烷基三甲基溴化铵（STAB）对复合粒子进行插层改性,从而提高其疏水性。所得MMT-Fe3O4-STAB颗粒经洗涤与磁分离后,均匀分散于有机硅改性聚氨酯（SiPU）基体中,制备得到MMT-Fe3O4-STAB@SiPU超疏水光热复合涂层。结果 涂层在填料含量为15%（质量分数）时达到超疏水阈值,形成具有微乳突的微纳二元结构,其静态水接触角高达158.4°,滚动角低至6.7°。该涂层在250~2 500 nm波段的宽谱吸收率达88.2%,在1个标准太阳光照（100 mW/cm2）下,仅85 s即可实现55.5 ℃的最大温升,光热转换效率高达72%。得益于MMT的二维支架作用,Fe3O4纳米颗粒（20~40 nm）分散均匀（500 µm×500 µm范围内Fe元素）,并使涂层的耐刮擦性相较于纯SiPU提升了3.5倍。在-15 ℃环境下的除冰测试表明,该涂层表面的冰层在光照下350 s内即可完全脱落,较空白对照组（>900 s）加速2.6倍。结论 该涂层体系不仅具备良好的超疏水性,还具备优异的光热除冰潜力,为复杂环境下功能防护材料的开发提供了可行路径。
Abstract
A novel superhydrophobic photothermal composite coating, MMT-Fe3O4-STAB@SiPU, is rationally designed by embedding magnetic, intercalated montmorillonite platelets into a silicone-modified polyurethane (SiPU) substrate. The originality lies in the one-pot construction of a hierarchical micro-/nano-binary architecture that simultaneously delivers ultra-low wettability (static water contact angle 158.4°, roll-off angle 6.7°) and rapid solar-to-thermal conversion (ΔTmax= 55.5 ℃ under 1 sun, 85 s). The key innovation is the use of montmorillonite (MMT) as a two-dimensional scaffold that (i) directs the in-situ nucleation of 20-40 nm Fe3O4 grains, preventing their aggregation, (ii) provides a cation-exchange gallery for quantitative intercalation of octadecyl-trimethyl-ammonium bromide (STAB, 1.4 × CEC) that lowers surface energy and expands the basal spacing from 1.52 nm to 1.85 nm, and (iii) reinforces the polymer through siloxane-silanol hydrogen bonding and physical inter-locking, giving 3.5-fold higher scratch resistance than neat SiPU.
The experimental protocol is reproducible and scalable. Brine-exfoliated MMT (2 g/L) was injected into a N2-shielded reactor at 65 ℃ and Fe2+/Fe3+ (1 : 2) chloride solution was added, followed by NH4OH to pH 10. Magnetic harvesting after 1 h yielded MMT-Fe3O4 that was immediately redispersed with STAB at 70 ℃ for 2 h. Complete bromide removal (AgNO3 test) guaranteed electrical neutrality. The resulting black powder (saturation magnetization 22 emu/g, sufficient for magnetic guidance yet below the 60 emu g-1 threshold that causes particle chaining) was spray-coated onto Al-2024 panels together with SiPU at 0.6 MPa, cured for 4 h at 60 ℃, giving a (45 ± 5) µm thick film with surface roughness Sa = 0.92 µm (laser confocal microscopy).
Systematic variation of filler (0wt.%-20wt.%) revealed a percolation-type transition to superhydrophobicity at 15wt.%, coinciding with the appearance of re-entrant micro-papillae (SEM) and a Cassie-Baxter fraction Φs = 0.13 calculated from the apparent contact angle. Elemental mapping (EDS) showed Fe coefficient of variation < 5% across 500 µm× 500 µm, evidencing uniform dispersion without secondary agglomeration. UV-Vis-NIR spectroscopy displayed a broadband absorption plateau of 88.2% (250-2 500 nm) for the 15wt.% coating and absorptivity saturated beyond this loading because the penetration depth (≈18 µm at 800 nm) approached the film thickness.
Photothermal response was quantified with an IR camera under AM 1.5 G (100 mW/cm2). The temperature jump followed a bi-exponential law: τ1=(8±1) s (surface heating) and τ2 =(42±3) s (in-depth diffusion), yielding a photothermal conversion efficiency η = 72%, calculated by η = (hAΔTmax - Qdiss)/Isolar, validated by a blank reference. The coating retained 96% of η after 100 h UV-B (0.7 W m-2) exposure, outperforming carbon-nanotube analogues (≈80% retention).
De-icing tests were conducted in a -15 ℃ climate chamber. A 3 mL droplet (φ = 8 mm) frozen on the tilted panel (20°) was irradiated (1 sun). Ice detached completely within 350 s for the 15wt% panel, controlling SiPU required > 900 s. The acceleration factor 2.6 was attributed to (i) localized superheat at the ice-solid interface (IR thermography showed +22 ℃ local ΔT), (ii) reduced interfacial toughness Γice from 42 J/m2 (Al) to 8 J/m2 (coating), and (iii) spontaneous water lubrication once partial melting occurred, verified by high-speed imaging (1 000 fps) that captured a sliding velocity of 4.7 mm/s.
Chemical durability was probed by immersing panels for 72 h in solvents and pH buffers. WCA remained ≥150° in ethanol and toluene, slightly declining to 131° in pH 3 medium. However, pH 10 caused WCA = 99° because base-catalysed siloxane hydrolysis flattened the nano-texture. Self-cleaning was demonstrated with carbon dust: a 10 µL water droplet removed 98% of contaminant in a single pass, leaving no trace residue.
The work establishes a universal design rule—"magnetically-intercalated clay nano-reinforcement"—to merge mechanical robustness, scalable fabrication, and dual-mode ice protection into one layer. The coating is immediately applicable to aluminium aircraft skins, and its magnetic responsiveness opens routes for robotic-assisted repair and recycling.
关键词
超疏水 /
蒙脱土 /
Fe3O4 /
光热涂层
Key words
superhydrophobicity /
montmorillonite /
Fe3O4 /
photothermal coating
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基金
国家重点研发计划（2021YFB2601703）
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