Dynamic Synergy of Photocatalysis and Hydrophobicity in PDMS-Grafted TiO2 Coatings for Long-Lasting Self-Cleaning

Dandan Ma; Lu Li; Jun Li; Xin Ji; Dan He; Jian-Wen Shi

doi:10.53941/dn.2026.100007

Abstract

A fundamental conflict in self-cleaning coatings lies in the trade-off between photocatalytic activity (requiring hydrophilic TiO₂) and hydrophobic repellency (requiring low-surface-energy polymers). Here, this bottleneck is broken through an in-situ grafting strategy that anchors polydimethylsiloxane (PDMS) chains onto TiO₂ surfaces via robust Si-O-Ti covalent bonds. By controlling the loading amount of TiO₂ in the sol, it enables the adjustment of the water contact angle, light transmittance, as well as self-cleaning performance of the coating. The resultant M-TiO₂ nanocatalyst exhibits excellent dispersion in hydrophobic media and imparts the composite coating with a water contact angle up to 163°. The dynamic photocatalytic process, decomposing organic stains while maintaining surface non-wettability, is systematically elucidated. Remarkably, the optimal coating (0.75 wt.% M-TiO₂) sustains a steady-state degradation rate of rhodamine B under UV light, achieving >90% conversion within 85 h, without compromising its water-repellent function. The covalent interface acts as a bridge between the organic components and the inorganic catalyst, significantly improving the dispersion uniformity and stability of TiO₂ nanoparticles in PDMS, thus endowing the resulting coating with good light transmittance in visible region, excellent self-cleaning performance and satisfied service durability. This work demonstrates that rational interface engineering can transform the inherent photocatalysis vs. hydrophobicity antagonism into a durable, dynamic synergy, providing a versatile platform for next-generation photocatalytic self-cleaning materials.

References

1.
Ren, J.; Zhang, T.; Jiao, S.; et al. Liquid-like PDMS Brushes/TiO₂ Microcapsule-Driven Coatings with Integrated Self-Healing, Photodegradation, and Antifouling Functions. J. Environ. Chem. Eng. 2025, 13, 119848. https://doi.org/10.1016/j.jece.2025.119848.
2.
Chavan, T.K.; Sethi, S.K. Eco-friendly Self-cleaning Coatings: Fundamentals, Fabrication, Applications, and Sustainability. J. Mater. Chem. B 2025, 13, 429–453. https://doi.org/10.1039/d4tb01392a.
3.
Zhao, J.; Liu, W.; Jin, Y.; et al. High-Transparency Mechanically Robust Glass-Based Dual-Layer Composite Superhydrophobic Coating: Enabling Solar Cell Self-Cleaning. Prog. Org. Coat. 2026, 211, 109726. https://doi.org/10.1016/j.porgcoat.2025.109726.
4.
Wang, X.; Ding, H.; Sun, S.; et al. Preparation of a Temperature-Sensitive Superhydrophobic Self-Cleaning SiO₂-TiO₂@PDMS Coating with Photocatalytic Activity. Surf. Coat. Technol. 2021, 408, 126853. https://doi.org/10.1016/j.surfcoat.2021.126853.
5.
Josyula, T.; Kumar Malla, L.; Thomas, T.M.; et al. Fundamentals and applications of surface wetting. Langmuir 2024, 40, 8293–8326. https://doi.org/10.1021/acs.langmuir.3c03339.
6.
Yang, X.; Wang, Y.; Tang, B.; et al. An Energy-Saving Photocatalytic Self-Cleaning Coating for Controlling Air Pollution in Highway Tunnels. Constr. Build. Mater. 2023, 375, 131008. https://doi.org/10.1016/j.conbuildmat.2023.131008.
7.
Liao, G.; Yao, W.; She, A.; et al. An Eco-Friendly Building Coating with High Self-Cleaning Capacity: Synergetic Effect of Super-Hydrophobicity and Photocatalytic Degradation. Constr. Build. Mater. 2023, 406, 133406. https://doi.org/10.1016/j.conbuildmat.2023.133406.
8.
Zhang, H.; Ju, G.; Zhou, L.; et al. Mechanical-Robust and Polymer-Based Superhydrophobic Coating toward Self-Cleaning and Anti-Corrosion. J. Clean. Prod. 2024, 469, 143161. https://doi.org/10.1016/j.jclepro.2024.143161.
9.
Hong, Z.; Yang, H.; Yuanhao, W.; et al. TiO₂/Silane Coupling Agent Composed Two Layers Structure: A Novel Stability Super-Hydrophilic Self-Cleaning Coating Applied in PV Panels. Energy Procedia 2017, 105, 1077–1083. https://doi.org/10.1016/j.egypro.2017.03.464.
10.
Prawira, R.A.; Ariyanti, D. TiO₂-M Self-Cleaning Coating with Antimicrobial and Superhydrophilic Properties. Mater. Today Proc. 2022, 63, S214–S221. https://doi.org/10.1016/j.matpr.2022.02.411.
11.
Wu, S.; Li, L.; Jiang, T.; et al. Excellent Self-Cleaning Surface Achieved through the Synergistic Effect of Superhydrophilicity and Photocatalysis of PVDF-TiO₂-HAP Coating. Surfaces and Interfaces 2024, 51, 104676. https://doi.org/10.1016/j.surfin.2024.104676.
12.
Xia, X.; Liu, J.; Liu, Y.; et al. Preparation and Characterization of Biomimetic SiO₂-TiO₂-PDMS Composite Hydrophobic Coating with Self-Cleaning Properties for Wall Protection Applications. Coatings 2023, 13, 224. https://doi.org/10.3390/coatings13020224.
13.
Wu, S.; Yang, X.; Cao, X.; et al. An innovative g-C₃N₄/SiO₂/PDMS composite coating with photocatalytic NO purification and self-cleaning functions. J. Mater. Sci. 2025, 60, 4645–4668. https://doi.org/10.1007/s10853-025-10723-x.
14.
Rudra, S.; Dhara, M.; Chakraborty, M.; et al. Fluorinated Polymer Brush- Grafted Silica Nanoparticles: Robust and Durable Self-Cleaning Coating Materials. ACS Appl. Polym. Mater. 2023, 5, 7443–7457. https://doi.org/10.1021/acsapm.3c01312.
15.
Yuan, Q.; Shi, C.; He, T. SiO₂/TiO₂ and PDMS Modified Self-Cleaning Coating and Its Application in Decorative UHPC Surface. Ceram. Int. 2024, 50, 6194–6206. https://doi.org/10.1016/j.ceramint.2023.11.338.
16.
Yang, L.; Yang, J.; Yang, D.Q. A durable superhydrophilic self-cleaning coating based on TiO₂–SiO₂-PAA nanocomposite for photovoltaic applications: Long-term outdoor study. Sol. Energy Mater. Sol. Cells 2024, 268, 112731. https://doi.org/10.1016/j.solmat.2024.112731.
17.
Syafiq, A.; Balakrishnan, V.; Ali, M.S.; et al. Application of Transparent Self-Cleaning Coating for Photovoltaic Panel: A Review. Curr. Opin. Chem. Eng. 2022, 36, 100801. https://doi.org/10.1016/j.coche.2022.100801.
18.
Syafiq, A.; Vengadaesvaran, B.; Rahim, N.A.; et al. Transparent Self-Cleaning Coating of Modified Polydimethylsiloxane (PDMS) for Real Outdoor Application. Prog. Org. Coat. 2019, 131, 232–239. https://doi.org/10.1016/j.porgcoat.2019.02.020.
19.
Zheng, C.; Lai, C.; Yi, G.; et al. Robust Superhydrophobic Anti-Corrosion Coating with Self-Cleaning and Anti-Fouling. Prog. Org. Coat. 2025, 200, 109047. https://doi.org/10.1016/j.porgcoat.2024.109047.
20.
Yuan, Q.; Shi, C.; He, T. Design and Performance Optimization of Self-Cleaning Coating on Decorative UHPC Surface. Constr. Build. Mater. 2023, 394, 132115. https://doi.org/10.1016/j.conbuildmat.2023.132115.
21.
Zhang, B.; Xue, X.; Zhao, L.; et al. Transparent Superhydrophobic and Self-Cleaning Coating. Polymers 2024, 16, 1876. https://doi.org/10.3390/polym16131876.
22.
Zhou, J.; Ci, L.; Hu, J.; et al. Preparation and Characterization of Superhydrophilic Self-Cleaning Coating for Solar Cell Cover Glass Applications. J. Adhes. Sci. Technol. 2023, 37, 2524–2536. https://doi.org/10.1080/01694243.2022.2143774.
23.
Kupalang, S.; Kanjana, N.; Wola, J.; et al. Surface Modification of Paper by TiO₂-PDMS-KH550 Coating with Superhydrophobic, Self-cleaning and Oil/Water Separating Properties. Fibers Polym. 2024, 25, 1533–1542. https://doi.org/10.1007/s12221-024-00506-7.
24.
Wang, S.; Wan, Y.; Song, N.; et al. Automatically Generated Datasets: Present and Potential Self-Cleaning Coating Materials. Sci. Data 2024, 11, 146. https://doi.org/10.1038/s41597-024-02983-0.
25.
Guo, R.; Bao, Y.; Zheng, X.; et al. Superhydrophobic and Photocatalytic Synergistic Self-Cleaning Coating Constructed by Hierarchically Structured Flower-like Hollow SiO₂@TiO₂ Spheres with Oxygen Vacancies. ACS Appl. Mater. Interfaces 2023, 15, 47447–47462. https://doi.org/10.1021/acsami.3c08571.
26.
Li, Y.; Deng, W.; Meng, Z.; et al. Superhydrophobic Graphite/TiO₂ Micro-Nano Composite Coatings: Fabrication and Properties. Colloids Surf. A 2026, 728, 138690. https://doi.org/10.1016/j.colsurfa.2025.138690.
27.
Kalmoni, J.J.; Blackman, C.; Carmalt, C.J. Surface Modification of Fluorine‐Free Superhydrophobic Materials with (Ultra‐)Thin TiO₂ Layers. Adv. Eng. Mater. 2025, 27, e202501319. https://doi.org/10.1002/adem.202501319.
28.
Kalmoni, J.J.; Blackman, C.S.; Carmalt, C.J. Tuneable Wetting of Fluorine‐Free Superhydrophobic Films via Titania Modification to Enhance Durability and Photocatalytic Activity. Adv. Mater. Interfaces 2024, 11, 2400519. https://doi.org/10.1002/admi.202400519.
29.
Hong, Z.; Yuan, Z.; Liu, Z.; et al. Superhydrophobic Modification of the PVDF Membrane by Fluorinated TiO₂Nanoparticles to Improve Membrane Distillation Performance. ACS EST Water 2025, 5, 2983–2991. https://doi.org/10.1021/acsestwater.4c01163.
30.
Liang, C.; Liu, X.; Teng, F.; et al. TiO₂/EP Superhydrophobic Composite Coating with Excellent Mechanical and Chemical Stability. Surf. Coat. Technol. 2024, 481, 130641. https://doi.org/10.1016/j.surfcoat.2024.130641.
31.
Yang, T.; Wang, L.; Luo, D.; et al. Bio-inspired superhydrophobic wood with high stability and durability constructed by using synergies of furfural resin and nano-TiO₂. Constr. Build. Mater. 2024, 432, 136632. https://doi.org/10.1016/j.conbuildmat.2024.136632.
32.
Zhao, Y.; Zhao, M.; Liu, M.; et al. Fabrication of a Robust Superhydrophobic Surface on Cotton Fabric with Dual Self-Cleaning Properties via In Situ Growth and Surface Modification. Langmuir 2025, 41, 33060–33072. https://doi.org/10.1021/acs.langmuir.5c05254.
33.
Li, S.; Zhang, J.; He, J.; et al. Functional PDMS elastomers: bulk composites, surface engineering, and precision fabrication. Adv. Sci. 2023, 10, 2304506. https://doi.org/10.1002/advs.202304506.
34.
Wang, Y.; Huang, Z.; Gurney, R.S.; et al. Superhydrophobic and photocatalytic PDMS/TiO₂ coatings with environmental stability and multifunctionality. Colloids Surfaces A Physicochem. Eng. Asp. 2019, 561, 101–108. https://doi.org/10.1016/j.colsurfa.2018.10.054.
35.
Ding, X.; Liu, R.; Zhao, J.; et al. Photocatalytic TiO₂/PDMS coating to drive self-cleaning: a facile approach for anti-stain silicone rubber surfaces. Polym. Bull. 2022, 79, 6431–6444. https://doi.org/10.1007/s00289-021-03789-5.
36.
Yuan, S.; Feng, Y.; Liang, S.; et al. ZnO@TiO₂/PDMS Superhydrophobic Antibacterial Coating with Photocatalytic Activity, Durability, and Self-Cleaning Properties. Materials 2026, 19, 2380. https://doi.org/10.3390/ma19112380.
37.
Zhao, Q.; Zhu, Y.; Gan, Y.; et al. Robust multifunctional protective textiles based on dispersion-enhanced PDMS/TiO₂/Al(OH)₃ composite coating. Prog. Org. Coat. 2026, 216, 110136. https://doi.org/10.1016/j.porgcoat.2026.110136.
38.
Wang, R.; Hashimoto, K.; Fujishima, A.; et al. Light-induced amphiphilic surfaces. Nature 1997, 388, 431–432. https://doi.org/10.1038/41233.
39.
Sakai, N.; Fujishima, A.; Watanabe, T.; et al. Quantitative Evaluation of the Photoinduced Hydrophilic Conversion Properties of TiO₂ Thin Film Surfaces by the Reciprocal of Contact Angle. J. Phys. Chem. B 2003, 107, 1028–1035. https://doi.org/10.1021/jp022105p.

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