Nanoengineered hydrophobic cotton fabric via ssurface functionalization of cuprous oxide (Cu2O) nanoflowers

Authors: KASHEM, MD NAYEEM HASAN - Oak Ridge National Laboratory; Nam, Sunghyun; Hillyer, Matthew; HASSAN, FAQRUL - Oak Ridge National Laboratory; LI, WEI - Texas Tech University; Fang, David

Submitted to: Applied Surface Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/3/2025
Publication Date: 7/5/2025
Citation: Kashem, M., Nam, S., Hillyer, M.B., Hassan, F., Li, W., Fang, D.D. 2025. Nanoengineered hydrophobic cotton fabric via ssurface functionalization of cuprous oxide (Cu2O) nanoflowers. Applied Surface Science. 711: 163980. https://doi.org/10.1016/j.apsusc.2025.163980.
DOI: https://doi.org/10.1016/j.apsusc.2025.163980

Interpretive Summary: Water-resistant fabrics are widely used in outdoor clothing, protective gear, and medical textiles. However, traditional waterproof textiles are often produced using per- and polyfluoroalkyl substances (PFAS) coatings, which have raised significant environmental and health concerns. This study presents a PFAS-free and robust method for making highly water-repellent cotton fabric by nanoengineering the cotton fibers. The method involves synthesizing copper-based nanoflowers both on the surface and within the cotton fibers. The surface of the nanoflowers is then grafted with a molecule with an inherent hydrophobic tail. As a result, the fabric effectively repels common liquids such as water, tea, milk, and coffee. The hydrophobic property remained intact even after multiple washes, demonstrating excellent wash durability. Moreover, the nanoengineered fabric exhibited self-cleaning properties with the dirt particles easily washed away from the surface. This technology provides a sustainable and long-lasting waterproofing solution for cotton, making it suitable for various applications with minimal cleaning requirements.

Technical Abstract: Hydrophobicity is an important property for designing high-performance cotton textiles. However, per- and poly-fluoroalkyl substances (PFAS) based coating, one of the traditional methods to impart hydrophobicity in cotton textiles, has raised significant environmental and health concerns. Herein, we nanoengineered cotton fiber to fabricate a highly hydrophobic fabric via a PFAS-free and robust method. This approach involves two steps (1) in situ growth synthesis of copper (I) oxide (Cu2O) nanoflower (CONF) both on the surface and within cotton fiber and (2) surface functionalization of CONF by grafting hydrophobic 1-decanethiol (DT) brushes via copper-thiol interaction. Comprehensive analyses of DT-functionalized CONF (DT-CONF) cotton fabric showed the uniform formation of CONF (with a copper concentration within the fabric of 51222 mg/kg). Moreover, Scanning Electron Microscope equipped with Energy Dispersive X-ray Spectroscopy (SEM-EDS) exhibited a homogeneous distribution of copper (11.5wt%) and sulfur (3.6wt%) on the surface. The DT-CONF cotton fabric exhibited high contact angles over 140° against various common liquids including water, tea, milk, and coffee. This hydrophobic property was wash-durable and introduced self-cleaning properties to the fabric. This fluorine-free method offers a promising route for developing hydrophobic, cotton-based textiles in applications such as outdoor gear, medical fabrics, and protective clothing.