This work addresses the critical challenge of mechanical fragility in superhydrophobic surfaces by developing a robust composite coating through a simple and scalable fabrication process. The innovation lies in a novel multi-scale structural design combined with a tailored curing strategy, which decouples the requirements for mechanical durability and extreme water repellency, enabling exceptional performance under harsh physical stresses.
The coating is fabricated using a sequential scrape-and-spray technique. The substrate is first prepared by standard cleaning and abrasion. The foundational layer is formulated by mixing epoxy resin E51 with large-particle quartz sand (Silica sand, 40-60 mesh) at a defined ratio to create a viscous paste, which is then scraped onto the substrate to a controlled thickness. This layer undergoes a first-stage partial cure at 60 ℃ for 30 minutes. Subsequently, the top functional layer is applied by spraying a suspension composed of E51 resin, fluorine-modified TiO2 nanoparticles (F-TiO2, 100 nm), and hydrophobic SiO2 nanoparticles (500 nm) in a solvent. The final system is then subject to a second-stage full cure at 60 ℃ for 2 hours, completing the dual-curing graded solidification protocol.
The surface topography and chemistry are characterized by scanning electron microscopy (SEM) and contact angle goniometry. Coating adhesion is quantitatively evaluated via a modified tape-peeling test, and wear resistance is rigorously assessed with a Taber abrasion tester under loads of 250 g and 750 g for thousands of cycles. The self-cleaning efficacy is demonstrated against both liquid contaminants (dye solutions).
A well-formed, durable superhydrophobic composite coating is successfully fabricated. SEM analysis confirms the intentional multi-scale hierarchy: the quartz sand forms a primary micro-scale rough contour, while the aggregated F-TiO2 and SiO2 nanoparticles construct a secondary nano-scale texture on top, essential for air pocket entrapment. Energy-dispersive X-ray spectroscopy (EDS) mapping verifies the uniform distribution of fluorine elements across the top surface, indicating successful low-surface-energy modification.
The coating achieves a maximum static water contact angle (WCA) of 151° and a minimum water sliding angle (SA) of <5°, demonstrating excellent superhydrophobicity and self-cleaning capability. Crucially, the mechanical stability tests yield outstanding results. After 3 000 cycles of Taber abrasion under a 250 g load, the coating retains its hydrophobicity. Even under a severe 750 g load for 600 cycles, it maintains a hydrophobic state. Furthermore, the coating exhibits exceptional adhesion, surviving 500 tape-peeling cycles with a post-test WCA still above 120° and an SA of approximately 5°.
The in-situ formed multi-scale structure and the graded curing strategy are identified as the primary reasons for the significant enhancement in mechanical durability. The large quartz sand particles in the bottom layer act as a mechanical buffer, absorbing and dissipating shear and compressive stresses from abrasion, thereby protecting the fragile nano-features in the top layer. The partial cure of the bottom layer creates a semi-rigid foundation that promotes strong mechanical interlocking with the substrate, while the full cure of the top layer ensures robust cohesion. This strategy effectively prevents delamination and crack propagation. The top-layer nanoparticle mixture (F-TiO2/SiO2) forms a densely packed, interpenetrating network within the epoxy, creating a tough, nano-rough surface with permanently low surface energy due to the fluorine groups. The synergy between the stress-relieving quartz sublayer and the reinforced nano-composite top layer is the core mechanism enabling the unprecedented combination of wear resistance and non-wetting performance.
In conclusion, a superhydrophobic epoxy composite coating with excellent wear resistance and strong adhesion is prepared via a scalable manufacturing process. The original multi-scale hierarchical design and the dual-layer graded curing strategy provide a generalizable blueprint for developing durable functional surfaces for practical industrial applications.
Key words
superhydrophobic /
self-cleaning /
double-layer structure /
wear resistance /
adhesion /
silane modification
{{custom_sec.title}}
{{custom_sec.title}}
{{custom_sec.content}}
References
[1] HOODA A, GOYAT M S, PANDEY J K, et al.A Review on Fundamentals, Constraints and Fabrication Techniques of Superhydrophobic Coatings[J]. Progress in Organic Coatings, 2020, 142: 105557.
[2] SHIGREKAR M, AMDOSKAR V.A Review on Recent Progress and Techniques Used for Fabricating Superhydrophobic Coatings Derived from Biobased Materials[J]. RSC Advances, 2024, 14(44): 32668-32699.
[3] WANG S Y, LIANG Z, HONG Q, et al.Green Route to Prepare Robust and Multifunctional Superhydrophobic Coatings[J]. Ceramics International, 2024, 50(3): 5857-5867.
[4] BARTHWAL S, BARTHWAL S.Engineering a Robust, Multifunctional Superhydrophobic/Oleophobic Microporous Aluminum Surface via a Two-Step Chemical Etching Process[J]. Surfaces and Interfaces, 2024, 46: 103933.
[5] YOU H, PENG Y, LI T, et al.One-Step Etching Fabrication of Superhydrophobic CuO/Cu2O/CuCl Hybrid Films with Integrated Anti-Corrosion, Self-Cleaning and Long- Term Stability[J]. Progress in Surface Science, 2025, 100(2): 100778.
[6] ZHU J Y, DUAN Y Z.Facilely Etching of Superhydrophobic Surface with Regular Mulriple Hierarchical Micro- Nano Structures for Crowning Wettability[J]. Applied Surface Science, 2024, 648: 159009.
[7] PAN H Z, QU C J, et al.Superhydrophobic and Abrasion- Resistant Coatings for Above-Ambient Passive Daytime Radiative Cooling via the Scalable Spraying Process[J]. ACS Applied Polymer Materials, 2025, 7(13): 8874-8882.
[8] ZHANG H L, JI X X, LIU L B, et al.Versatile, Mechanochemically Robust, Sprayed Superomniphobic Coating Enabling Low Surface Tension and High Viscous Organic Liquid Bouncing[J]. Chemical Engineering Journal, 2020, 402: 126160.
[9] LIU R D, LI K, MA J, et al.Formation of Highly Robust Superhydrophobic Nanocomposite Coatings via Dual Spraying Technique[J]. Advanced Engineering Materials, 2024, 26(11): 2400153.
[10] ZHANG W J, LIU X Z, ZHENG C B, et al.Anti- Corrosion, Anti-Icing, and Mechanically Robust Superhydrophobic Coating Based on Kaolin Particles[J]. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2025, 713: 136504.
[11] LEE S, HONG H R, PARK C H, et al.Enhancing Superhydrophobicity of Fabrics via Chemical Vapor Deposition and Thermal Aging[J]. Journal of Applied Polymer Science, 2025, 142(48): e57887.
[12] CHEN F, KALMONI J J, LI S H, et al.Robust, Fluorine- Free Superhydrophobic Films on Glass via Epoxysilane Pretreatment[J]. Langmuir, 2025, 41(3): 1556-1567.
[13] ZHU Y R, LI H Q, HUANG W, et al.Facile Fabrication of Superhydrophobic Wood Aerogel by Vapor Deposition Method for Oil-Water Separation[J]. Surfaces and Interfaces, 2023, 37: 102746.
[14] GUO Q, ZHANG Y, LIU Y J, et al.Durable Siloxane/ Polyurea Superhydrophobic Coatings Based on Microphase Separation Method and Armour Protection Strategy[J]. Progress in Organic Coatings, 2025, 200: 108989.
[15] GUO H S, YANG C C, WANG C X.Sodium Alginate/ Epoxy Resin is Separated by Emulsion Phase to Fabricate a Strong Superhydrophobic Coating[J]. Surfaces and Interfaces, 2024, 45: 103941.
[16] WANG X, WANG H Y, SUN Y Y, et al.Preparation of Highly Adhesion Hydrophobic Membrane and Superhydrophobic Membrane via Electrospinning[J]. Advanced Engineering Materials, 2023, 25(24): 2300806.
[17] WANG X H, LI X M.Stabilized Superhydrophobic Composite Membranes Prepared by Electrospinning for Oil-Water Separation[J]. Polymers for Advanced Technologies, 2024, 35(3): e6329.
[18] IZADI N, MONTAZER M, HAJI A.Janus Flame- Retardant Polyester Fabric with One-Way Water Transfer for Fog Collection: Influence of Plasma Duration, Aluminum Phosphate, and TiO2 Nanoparticles[J]. Heliyon, 2025, 11(3): e42400.
[19] 侯计伟, 张颖, 黄欣怡, 等. 超疏水棉织物的制备及功能化应用研究进展[J]. 上海纺织科技, 2025, 53(11): 9-15.
HOU J W, ZHANG Y, HUANG X Y, et al.Research Progress on Preparation and Functional Applications of Superhydrophobic Cotton Fabrics[J]. Shanghai Textile Science & Technology, 2025, 53(11): 9-15.
[20] 许慧凌, 林明华, 王华, 等. 功能性超疏水防冰涂层的研究进展[J]. 涂料工业, 2025, 55(12): 82-86.
XU H L, LIN M H, WANG H, et al.Research Progress in Functional Superhydrophobic Anti-Icing Coating[J]. Paint & Coatings Industry, 2025, 55(12): 82-86.
[21] MILIONIS A, LOTH E, BAYER I S.Recent Advances in the Mechanical Durability of Superhydrophobic Materials[J]. Advances in Colloid and Interface Science, 2016, 229: 57-79.
[22] LI B C, LIANG W D, WEI J F, et al.Liquid Impalement Resistant and Mechanically Robust Superhydrophobic Coatings with Anti-Icing Performance[J]. Advanced Materials Technologies, 2025, 10(17): e00387.
[23] GU W C, LI W B, ZHANG Y, et al.Ultra-Durable Superhydrophobic Cellular Coatings[J]. Nature Communications, 2023, 14: 5953.
[24] FU X, XU S Y.Preparation of CNF Synergistic Enhanced EP/SiO2 Superhydrophobic Coating by One-Step Spraying Method: Achieving Wear Resistance and Strong Adhesion Function[J]. Progress in Organic Coatings, 2025, 209: 109555.
[25] WU H P, ZHOU J, ZHAO T Z, et al.Laser Direct Writing Micro/Nano Hierarchical Honeycomb Surface Structures for Robust Superhydrophobic Titanium Alloys[J]. Applied Surface Science, 2026, 715: 164418.
[26] WANG Y L, HUANG Z W, GURNEY R S, et al.Superhydrophobic and Photocatalytic PDMS/TiO2 Coatings with Environmental Stability and Multifunctionality[J]. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2019, 561: 101-108.
[27] LI X W, MA C H, SHI T, et al.Waterborne Robust Superhydrophobic PFDTES@TiO2-PU Coating with Stable Corrosion Resistance, Long-Term Environmental Adaptability, and Delayed Icing Functions on Al-Li Alloy[J]. Journal of Materials Research and Technology, 2024, 32: 3357-3370.
[28] SHI L F, YAN H, ZHAO S, et al.A Durable Superhydrophobic Composite Coating towards Superior Anticorrosion/ Wear Properties[J]. Applied Surface Science, 2024, 655: 159662.
[29] LI K Q, XIANG J M, ZHOU J L, et al.Self-Healing and Wear Resistance Stable Superhydrophobic Composite Coating with Electrothermal and Photothermal Effects for Anti- Icing[J]. Progress in Organic Coatings, 2023, 177: 107415.
[30] WEN X J, LI H L, LI R Z, et al.Coral-Inspired Superhydrophobic Triboelectric Nanogenerators with Unprecedented Wear Resistance and Sub-Zero Temperature Self- Healing Capability[J]. Advanced Functional Materials, 2025, 35(31): 2501706.
Funding
Shandong Province Enterprise Technology Innovation Project (2025637010001340, 2025637010001569)
PDF(13632 KB)
