Bio-inspired construction of super-hydrophobic, eco-friendly multifunctional and bio-based cotton fabrics via impregnation method

Halloysite-based inorganic-organic hybrid coatings for durable flame retardant, hydrophobic and antibacterial properties of cotton fabrics

Developing durable protective cotton fabrics (CF) against potential environmental dangers such as fire hazards and bacterial growth remains an imperative but tough challenge. In this study, flame retardant, antibacterial and hydrophobic CF were successfully prepared via two-step coating. The inner coating entailed polyelectrolyte complexes consisting of polyethyleneimine and ammonium polyphosphate with the goal of enhancing the flame retardancy of CF. Halloysite nanotubes (HNTs), a kind of tubular silicate mineral, were creatively modified and introduced to multifunctional coatings to improve flame retardant and antibacterial properties of CF. N-halamine modified HNTs (HNTs-EA-Cl) and polydimethylsiloxane were applied as the outer coating to endow CF with antibacterial and hydrophobic properties and further improve the flame retardancy of CF. After halloysite-based inorganic-organic hybrid coatings, the limiting oxygen index of the treated samples (PAHP-CF) was over 28 %, and the release of heat and smoke was significantly inhibited. PAHP-CF could inactivate 100 % E. coli and S. aureus within 2 h. More importantly, PAHP-CF showed excellent hydrophobicity with a water contact angle of 148° and exhibited great prevention of bacterial adhesion. PAHP-CF exhibited excellent washing durability undergoing 5 washing cycles. This study promotes the development of multifunctional coatings and offers a new way to manufacture multifunctional cotton fabrics.

Phytic acid-induced durable fire-proof and hydrophobic complex coating for versatile cotton fabrics

To address the current development requirements for multifunctional cotton fabrics, a phytic acid-induced flame-retardant hydrophobic coating containing nitrogen (N), phosphorus (P), and silicon (Si) was grafted on the surface of cotton fabrics using a facile step-by-step immersion method. The limiting oxygen index value improved to 31.2 %, decreasing to 26.7 % after 50 laundering cycles, while the fabric remained self-extinguishing effect in the vertical flammability test and showed a water contact angle of 126.1°. Cone calorimetry test showed that the modified fabric could not be ignited at the irradiation heat flux of 35 kW/m2. When the irradiation heat flux was raised to 50 kW/m2, there was a significant decline in the peak heat release rate of the modified cotton fabric, which decreased by 43.2 % to a remarkably low value of 114.0 kW/m2, indicating excellent flame-retardant properties. The analysis of the flame-retardant mechanism uncovered that the modified coating exhibited a significant dual flame-retardant mechanism involving both the gaseous phase and the condensed phase. Additionally, the oil-water separation tests revealed that the separation efficiency of the modified cotton fabrics was as high as 97.1 % and remained around 96 % after 10 cycles, which made them reusable for the clean-up of hazardous chemicals.

A bio-based durable reactive flame retardant for cotton fabric based on lentinan

Cotton fabric has extensive application due to its comfort and breathability. However, the inherent flammability limits its wide application. Durable polysaccharide-based flame retardants with a low impact on the softness of fabrics are rarely reported. In this work, a novel flame retardant ammonium phosphate of lentinan (APLNT) was synthesized and grafted on the surface of cotton fabric. The treated cotton fabric had a high limiting oxygen index (LOI) value of 43.3 % and passed the vertical burning test (VBT) with a 21.1 % weight gain of APLNT. Compared with control cotton, the peak heat release rate and total heat release values of Cotton-APLNT2 decreased by 92.8 % and 50.9 %, respectively. In addition, the cotton fabric still passed the VBT and kept an LOI value of 27.0 % even after 50 laundering cycles, indicating that the fabric can be used for daily needs. More importantly, the treated fabric remains soft. This research provided a new strategy for preparing bio-based durable flame retardant cotton fabrics.

Preparation of multifunctional cellulose macromolecule blended fabrics through internal and external synergy by N1, N6-bis (ethylene oxide-2-ylmethyl) hexane-1,6-diamine

With the diversification of people's demand for textile functions, the preparation of multifunctional fabrics is still a current research hotspot. In this study, the water-soluble epoxy compound N1, N6-bis(oxiran-2-ylmethyl) hexane-1,6-diamine (EH) was introduced into cellulose macromolecule blended fabrics (cotton/modal) by two-phase vaporization technique, resulting in excellent wrinkle, hydrophobicity, and certain UV protection effects. It could be observed by electron microscopy that EH formed a polymer film on the fiber surface. In addition, the results of EDS scans and fiber swelling rate tests showed that EH was uniformly distributed and formed a cross-linked structure in the amorphous zones inside the fibers. Compared with the control fabrics, the wrinkle recovery angle of the EH-treated fabric was increased by 39.7 %. The fabrics could reach a contact angle of 136.9°, providing excellent hydrophobic effect. In addition, the fabrics achieved certain UV protection effects (UPF of 50+). The EH-treated fabrics were less stabilized in strong acid and alkali conditions, but exhibited greater durability in other environments. In summary, the internal and external synergistic effects of EH in forming polymer films on the fibers surface and internal cross-linking structures provided a cleaner, simple, and feasible method for the preparation of multifunctional cellulose macromolecule fibers textiles.

One pot application of a green chemistry-based finish for cotton fabric, providing hydrophobic, flame retardant, and antimicrobial properties

Fluorinated and formaldehyde-based compounds impart excellent hydrophobicity and flame-retardant properties to cotton fabrics. However, they come with various health and environmental risks. A novel hydrophobic, flame retardant, and antimicrobial finishing agent free from fluorine and formaldehyde was synthesized. The diammonium phosphate octadecyl citrate (DAPOC) was synthesized by using stearic acid (octadecanoic acid), citric acid (propane-1,2,3-tricarboxylic acid), and diammonium hydrogen phosphate. It was grafted onto the cotton fabrics by employing the conventional pad-dry-cure method. The results indicated that this newly developed finish could be chemically bonded to cotton fabrics through C-O-C covalent bonds. The contact angle of the cotton fabric finished with a 12% concentration of the finishing agent reached 151.9°. Additionally, the finished cotton fabrics displayed evident flame-retardant properties. After undergoing 20 laundering cycles, DAPOC maintained strong hydrophobic and flame-retardant characteristics, demonstrating its durability. The chemical structure of DAPOC was verified by nuclear magnetic resonance spectroscopy (1H-NMR). The thermogravimetric analysis confirmed the flame-retardant nature of the treated cotton fabric samples. Scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDX), and Fourier-transform infrared spectroscopy (FTIR) results demonstrated the successful grafting of the newly created finish onto the cotton fiber. X-ray diffraction (XRD) spectra depicted that the crystalline structure of finished cotton fabric remained mostly unaltered. Furthermore, the finished cotton fabric exhibited commendable antimicrobial properties due to the inclusion of citric acid.

Integrating multifunctional highly efficient flame-retardant coatings with superhydrophobicity, antibacterial property on cotton fabric

There has been a growing interest in bio-based flame-retardant coating layer with good antibacterial activity for cotton fabric owing to the arising environmental pollution and viral and bacterial infectious risks. In this study, multifunctional flame-retardant coatings with superhydrophobicity and antibacterial property were integrated on cotton fabric through two-step method. The first layer of phosphorylated chitosan (PCS) biobased coating (C4) endowed the fabric highly efficient flame retardancy and antibacterial activity, and the second layer of modified poly(2-hydroxyethyl methacrylate phosphate ester) (PHEMAP) coating by perfluorooctyltriethoxysilane (P/F) provided the fabric excellent superhydrophobicity and self-cleaning ability. The C4-P/F fabric exhibited a shorter damage length of only 6.2 cm and achieved a higher char yield of 22.3 % than the C4 fabric in the vertical combustion test, and the limited oxygen index of the C4-P/F fabric increased to 32.5 %. The water contact angle (WCA) of the C4-P/F fabric reached above 150 o. Moreover, the C4-P/F fabric exhibited excellent antibacterial activity against Escherichia coli and Staphylococcus aureus. The highly efficient flame-retardant, superhydrophobic, antibacterial fabric is promising in home and public decoration, fire protection fields.

Multifunctional composite coatings with hydrophobic, UV-resistant, anti-oxidative, and photothermal performance for healthcare

Personal protective textiles have attracted extensive interest since Corona Virus Disease 2019 has broken out. Moreover, developing eco-friendly, multifunctional waterproof, and breathable surface is of great importance but still faces enormous challenges. Notably, good hydrophobicity and breathability are necessary for protective textiles, especially protective clothing and face masks for healthcare. Herein, the multifunctional composite coatings with good UV-resistant, anti-oxidative, hydrophobic, breathable, and photothermal performance has been rapidly created to meet protective requirements. First, the gallic acid and chitosan polymer was coated onto the cotton fabric surface. Subsequently, the modified silica sol was anchored on the coated cotton fabric surface. The successful fabrication of composite coatings was verified by RGB values obtained from the smartphone and K/S value. The present work is an advance for realizing textile hydrophobicity by utilizing fluorine-free materials, compared with the surface hydrophobicity fabricated with conventional fluorinated materials. The surface free energy has been reduced from 84.2 to27.6 mJ/m2 so that the modified cotton fabric could repel the ethylene glycol, hydrochloric acid, and sodium hydroxide solutions, respectively. Besides, the composite coatings possesses lower adhesion to deionized water. After 70 cycles of the sandpaper abrasion, the fluorine-free hydrophobic coatings still exhibits good hydrophobicity with WCA of 124.6 ± 0.9°, with overcoming the intrinsic drawback of the poor abrasion resistance of hydrophobic surfaces. Briefly, the present work may provide a universal strategy for rapidly creating advanced protective coatings to meet personal healthcare, and a novel method for detecting RGB values of composite coatings by smartphone.

Recent Advances in Superhydrophobic Surfaces and Applications on Wood

Superhydrophobic substances were favored in wood protection. Superhydrophobic treatment of wood is of great significance for improving the service life of wood and expanding its application fields, such as improving dimensional stability, durability, UV stability, and reducing wetting. The superhydrophobic phenomenon is attributed to the interaction of micro/nano hierarchical structure and low surface energy substances of the wood surface. This is the common method for obtaining superhydrophobic wood. The article introduces the common preparation methods of superhydrophobic wood material coatings and their mechanisms. These techniques include lithography, sol–gel methods, graft copolymerization, chemical vapor deposition, etc. The latest research progress of superhydrophobic wood material coatings application at domestic and overseas is reviewed, and the current status of superhydrophobic coating application in wood materials and construction is summarized. Finally, superhydrophobic on wood in the field of applied research is presented, and the development trend in the field of functional improvement of wood is foreseen.

High-Efficient Flame-Retardant Finishing of Cotton Fabrics Based on Phytic Acid

In this study, an efficient phosphorus-containing flame retardant, PAPBTCA, was synthesized from phytic acid, pentaerythritol, and 1,2,3,4-butane tetracarboxylic acid, and its structure was characterized. PAPBTCA was finished on cotton fabrics by the pad-dry-curing process, and the flame retardancy, flame-retardant durability, and wrinkle resistance of the obtained flame-retardant fabrics were investigated. It should be noted that the heat release rate value of the flame-retardant cotton fabrics treated with 200 g/L PAPBTCA decreased by 90% and its excellent flame retardancy was maintained after 5 washing cycles. Meanwhile, the wrinkle resistance of flame-retardant cotton fabrics has been significantly improved. In addition, compared with the control, the breaking force loss of PAPBTCA-200 in the warp and weft directions was 24% and 21%, respectively. This study provides a new way to utilize natural phosphorus-based flame retardants to establish multifunctional finishing for cotton fabrics.

Research progress on eco-friendly superhydrophobic materials in environment, energy and biology

In the past few years, bioinspired eco-friendly superhydrophobic materials (EFSMs) have made great breakthroughs, especially in the fields of environment, energy and biology, which have made remarkable contributions to the sustainable development of the natural environment. However, some potential challenges still exist, which urgently need to be systematically summarized to guide the future development of this field. Herein, in this review, initially, we discuss the five typical superhydrophobic models, namely, the Wenzel, Cassie, Wenzel-Cassie, "lotus", and "gecko" models. Then, the existence of superhydrophobic creatures in nature and artificial EFSMs are summarized. Then, we focus on the applications of EFSMs in the fields of environment (self-cleaning, wastewater purification, and membrane distillation), energy (solar evaporation, heat accumulation, and batteries), and biology (biosensors, biomedicine, antibacterial, and food packaging). Finally, the challenges and developments of eco-friendly superhydrophobic materials are highlighted.