Highly Anti-UV Properties of Silk Fiber with Uniform and Conformal Nanoscale TiO2 Coatings via Atomic Layer Deposition

A triple-crosslinking strategy for high-performance regenerated cellulose fibers derived from waste cotton textiles

Regenerated cellulose fibers has attracted increasing attention for high-grade textile raw materials and industrial textiles, but the low mechanical property caused by differences in regenerated raw materials and production levels limits its commercial application in the product diversity. Herein, we proposed a novel triple-crosslinking strategy by coupling with hydrogen bonds, chemical crosslinking, and internal mineralization from multiple pulsed vapor phase infiltration (MPI) to improve the mechanical performance of regenerated cellulose fibers. A binary solvent composed of ionic liquid (IL) and dimethyl sulfoxide (DMSO) is used to dissolve waste cotton textile and then wet spinning. Dual-crosslinking is firstly achieved by coupling glutaraldehyde (GA) and cellulose reaction. Subsequently, a metal oxide is intentionally infiltrated into inner cellulosic through MPI technology to form a third form of crosslinking, accompanied by the ultra-thin metal oxide nano-layer onto the surface of regenerated cellulose fibers. Results showed that the triple-crosslinking strategy has increased the tensile stress of the fiber by 43.57 % to 287.03 MPa. In all, triple-crosslinking strategy provides a theoretical basis and technical approach for the reinforcement of weak fibers in waste cotton recycling, which is expected to accelerate the development of the waste textile recycling industry and promote of the added-value of regenerated products.

Polylactic acid based Janus membranes with asymmetric wettability for directional moisture transport with enhanced UV protective capabilities

Efficient directional moisture transport can remove excess sweat away from the human body and keep the body dry; fully utilizing this functionality to improve the wearing experience is urgently needed in the area of functional textiles. Herein, a facile strategy is used to design an eco-friendly and biodegradable PLA membrane with enhanced directional moisture transport and UV protection abilities. The PLA-based Janus membrane with asymmetric wettability is fabricated via sol-gel and electrospinning methods. Titanium dioxide nanoparticles (TiO2) were anchored onto the surface of the PLA fabric during the TiO2 sol-gel fabrication process using polydopamine, forming superhydrophilic TiO2@PDA-PLA. Then a thin PLA fibrous membrane layer showing hydrophobicity was electrospun onto this (PLA-E). The Janus PLA-E/TiO2@PDA-PLA membrane was successfully fabricated. Due to the asymmetric wettability and anchored TiO2, the PLA-E/TiO2@PDA-PLA Janus membrane exhibits efficient directional moisture transport and excellent UV protection abilities, and this work may provide a new pathway for fabricating multifunctional personal protective materials and have attractive potential applications in the future.

Organic/Inorganic Hybrid Fibers: Controllable Architectures for Electrochemical Energy Applications

Organic/inorganic hybrid fibers (OIHFs) are intriguing materials, possessing an intrinsic high specific surface area and flexibility coupled to unique anisotropic properties, diverse chemical compositions, and controllable hybrid architectures. During the last decade, advanced OIHFs with exceptional properties for electrochemical energy applications, including possessing interconnected networks, abundant active sites, and short ion diffusion length have emerged. Here, a comprehensive overview of the controllable architectures and electrochemical energy applications of OIHFs is presented. After a brief introduction, the controllable construction of OIHFs is described in detail through precise tailoring of the overall, interior, and interface structures. Additionally, several important electrochemical energy applications including rechargeable batteries (lithium-ion batteries, sodium-ion batteries, and lithium-sulfur batteries), supercapacitors (sandwich-shaped supercapacitors and fiber-shaped supercapacitors), and electrocatalysts (oxygen reduction reaction, oxygen evolution reaction, and hydrogen evolution reaction) are presented. The current state of the field and challenges are discussed, and a vision of the future directions to exploit OIHFs for electrochemical energy devices is provided.

TiO2 Coatings Via Atmospheric-Pressure Plasma-Enhanced Chemical Vapor Deposition for Enhancing the UV-Resistant Properties of Transparent Plastics

Herein, TiO₂ coatings were deposited on photodegradable polymers for protection from UV irradiation using the atmospheric-pressure plasma-enhanced chemical vapor deposition (AP-PECVD) technique. Polymethylmethacrylate (PMMA) and polycarbonate (PC) substrates were coated with titanium tetraisopropoxide as the precursor in an open-air atmospheric-pressure nonequilibrium argon plasma jet. The AP-PECVD-derived TiO₂ coatings exhibited good adhesion to PMMA and PC. The TiO₂ coatings could shield more than 99% of UV light in the wavelength range of 200-300 nm, without affecting the transmittance of visible light. UV irradiation tests on polymer films demonstrated that the degradation rates of PMMA and PC were significantly reduced by one-tenth after they were coated with TiO₂ films.

Interplay between Light and Functionalized Silk Fibroin and Applications

Silkworm silk has been considered to be a luxurious textile for more than five thousand years. Native silk fibroin (SF) films have excellent (ca. 90%) optical transparency and exhibit fluorescence under UV light. The silk dyeing process is very important and difficult, and methods such as pigmentary coloration and structural coloration have been tested for coloring silk fabrics. To functionalize silk that exhibits fluorescence, the in vivo and in vitro assembly of functional compounds with SF and the resulting amplification of fluorescence emission are examined. Finally, we discuss the applications of SF materials in basic optical elements, light energy conversion devices, photochemical reactions, sensing, and imaging. This review is expected to provide insight into the interaction between light and silk and to inspire researchers to develop silk materials with a consideration of history, material properties, and future prospects.

Fabrication of Superhydrophobic and UV-Resistant Silk Fabrics with Laundering Durability and Chemical Stabilities

To obtain a superhydrophobic surface, SiO2 nanoparticles are deposited on the surface of silk fabric (SF) by Plasma Enhanced Chemical Vapor Deposition (PECVD) to form a hierarchical roughness structure. In addition, a durable superhydrophobic SiO2@silk fabric was further prepared by hexamethyldisilazane (HMDS) modification. Compared with bare silk, the surfaces of the SiO2@silk fabric exhibit higher surface roughness and excellent superhydrophobic activity, with a contact angle (CA) of ~152°. The excellent UV resistance of SiO2@silk fabric was confirmed with high UV protection factor (UPF) values and a low UV transmittance. Moreover, both the laundering durability and chemical stability of the SiO2@silk fabric were improved. Overall, this method is recognized as a promising approach to produce high-end fabric development. It can also guide the design of multifunctional fiber materials in the future.

Impact of adding glucose-coated water-soluble silver nanoparticles to the silkworm larval diet on silk protein synthesis and related properties

Biological modifications of the silk fibroin (silk) material have broad applications in textiles, biomedical materials and other industrial materials. It is economical to incorporate nanoparticles to the biosynthesis of silk fibroin by adding them to silkworm larval diets. This strategy may result in the rapid stable production of modified silk. Glucose-coated silver nanoparticles (AgNPs) were used to improve the AgNPs' biocompatibility, and the AgNPs were efficiently incorporated into silk by feeding. Larvae fed with AgNPs produced silk with significantly improved antibacterial properties and altered silk secondary structures. Both positive and negative effects on the growth and synthesis of silk proteins were observed after different AgNPs doses. Larvae feeding with low concentration of 0.02% and medium 0.20% AgNPs have greater transfer efficiencies of AgNPs to silk compared with feeding high concentration of 2.00% AgNPs. In addition, the elongation and tensile strength of the produced silk fibers were also significantly increased, with greater mammalian cell compatibility. The appropriate AgNPs concentration in the diet of silkworms can promote the synthesis of silk proteins, enhance their mechanical properties, improve their antibacterial property and inhibit the presence of Gram-negative bacteria.

Facile and Effective Fabrication of Highly UV-Resistant Silk Fabrics with Excellent Laundering Durability and Thermal and Chemical Stabilities

As the most favored high-quality biopolymer, silk fiber is widely used in the textile and medical industries owing to its impressive mechanical properties, wear comfort properties, and biocompatibility. However, its photoinstability, chemical instability, and thermal instability seriously hinder its utilization in luxurious fashionable apparels. Therefore, we herein report the preparation of an ultrathin and uniform TiO₂-Al₂O₃ cloth with a thickness of just six in a thousand of fiber on silkworm silk fiber via atomic layer deposition. In this ultrathin composite cloth, the outer TiO₂ layer acts as a sacrificial ultraviolet (UV) absorbent to dissipate large amounts of UV energy. Free radicals and electrons generated by the TiO₂ layer are effectively blocked outside the surface of the bulk silk fiber by the inner insulating Al₂O₃ layer. The excellent UV-resistance of the modified silk fiber was confirmed by a lack of fade in the silk fabric after exposure to UV light for 60 min (equal to continuous exposure to strong sunlight for 3285 days). Compared with silk fiber, the tenacity of the prepared SF-200Al₂O₃-800TiO₂ increased by 18.9% even after sunlight exposure. In addition, both the chemical and thermal stabilities of the modified silk fiber were improved. This technology is expected to have potential applications in various fields, such as high-end fabric development and smart materials, and will further guide material design for future innovations in functional fibers and devices.

Study on the Photocatalytic and Antibacterial Properties of TiO2 Nanoparticles-Coated Cotton Fabrics

Herein, the amino-capped TiO₂ nanoparticles were synthesized using tetrabutyl titanate and amino polymers by a two-step sol-gel and hydrothermal method technique for the fabrication of functional cotton fabric. The prepared TiO₂ nanoparticles and the treated cotton fabric were characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), field emission scanning electron microcopy (FE-SEM) photocatalytic and antibacterial measurement. The results indicate the typical characteristic anatase form of the amino-capped TiO₂ NPs with an average crystallite size of 14.9 nm. The treated cotton fabrics exhibit excellent antibacterial property and good photocatalytic degradation of methylene blue.

Multifunctional films with a highly oriented "nano-brick wall" structure by regulating modified TiO2@graphene oxide/poly(vinyl alcohol) nanocomposites

High-performance packaging materials featuring a superior gas barrier and UV resistance as well as excellent mechanical properties are highly desirable but are still encountering serious challenges in the food, pharmaceutical and electronic industries. Here, a multifunctional film based on a modified titanium dioxide@graphene oxide/poly(vinyl alcohol) (TiO2@GO/PVA) nanocomposite with a multilayer nano-brick wall structure is rationally designed and fabricated by a facile solution casting approach. The modified TiO2 nanoparticles, assembled on the surface and edges of GO, are employed as bridges to construct the GO edge-to-edge alignment. Then, they tightly combine with PVA chains, acting as the mortar, to form a multilayer compact film. Therefore, the oxygen permeability of the nanocomposite film decreases to 0.119 × 10-17 cm3·cm (cm2·s·Pa)-1 with the addition of 1.0 wt% GO and 1.2 wt% modified TiO2, reduced by 93% compared with pure PVA film. More impressively, it is increased by only 5.9% after 9 h of ultraviolet light irradiation, which shows its exceptional UV resistance ability. In addition, the mechanical performance, thermal stability and water resistance are substantially improved. The developed modified TiO2@GO/PVA nanocomposite films with outstanding performance can be perceived as a green biodegradable material for a wide range of packaging industries.

UV-Protective TiO2 Thin Films with High Transparency in Visible Light Region Fabricated via Atmospheric-Pressure Plasma-Enhanced Chemical Vapor Deposition

This article focuses on control of film thickness and roughness to improve the ultraviolet (UV)-protective performance of TiO₂ films prepared by atmospheric-pressure plasma-enhanced chemical vapor deposition using titanium(IV) isopropoxide (TTIP) as the precursor and argon as the plasma working gas. The relationship between the film morphology and UV-protective performance suggested that a decrease in roughness is the key factor to achieve performance improvement. The effects of substrate temperature and precursor concentration were investigated, and the results showed that an increase in both substrate temperature and precursor concentration reduced the roughness and improved the transparency to visible light without reducing the ability to block UV light. Finally, a TiO₂ film with greater than 99% UV light blockage and greater than 95% transmittance of visible light was obtained.

Highly Efficient UV Protection of the Biomaterial Wood by A Transparent TiO2/Ce Xerogel

Titanium dioxide is widely used in sunscreens because of its strong ultraviolet (UV) light absorbing capabilities and its resistance to discoloration under UV exposure. However, when deposited as a thin film, the high refractive index of titanium dioxide typically results in whiteness and opacity, which limits the use of titanium dioxide for material surfaces, for which long-term natural appearance is of high relevance. Since the whitish appearance is due to the strong light scattering and reflection on the interface of oxide particles and air, one can increase the transparency of TiO₂ coatings by forming a continuous TiO₂ layer. The purpose of the present article is 2-fold. First, we show that, in the presence of cerium ammonium nitrate, titanium dioxide can be turned from a white powder into a TiO₂/Ce xerogel via a facile bottom-up fabrication process. Second, we demonstrate that the transparent TiO₂/Ce xerogel can diminish surface deterioration induced by UV light and preserve the natural appearance of the highly abundant biomaterial wood. Furthermore, EPR spectroscopy revealed that the TiO₂/Ce xerogel coating suppresses free radical generation on wood surfaces upon UV irradiation. Our research expands the applicability of the protective effect of titanium dioxide to coatings for natural engineering materials, which will become increasingly important in future bioeconomies.

Facile and Effective Coloration of Dye-Inert Carbon Fiber Fabrics with Tunable Colors and Excellent Laundering Durability

Carbon fiber is a good candidate in various applications, including in the military, structural, sports equipment, energy storage, and infrastructure. Coloring of carbon fiber has been a big challenge for decades due to their high degrees of crystallization and insufficient chemical affinity to dyes. Here, multicolored carbon fiber fabrics are fabricated using a feasible and effective atomic layer deposition (ALD) technique. The vibrant and uniform structural colors originating from thin-film interference is simply regulated by controlling the thickness of conformal TiO₂ coatings on the surface of black carbon fibers. Impressively, the colorful coatings show excellent laundering durability, which can endure 50 cycles of domestic launderings. Moreover, the mechanical properties only drop off slightly after coloring. Overall, these results open an alternative avenue for development of TiO₂ nanostructured films with multifunctional features grown using ALD technologies. This technology is speculated to have potential applications in various fields such as color engineering and radiation-proof fabrics and will further guide material design for future innovations in functional optical and color-display devices. More importantly, this research demonstrates a route for the coloring of black carbon fiber-based materials with vibrant colors.

Higher UV-shielding ability and lower photocatalytic activity of TiO2@SiO2/APTES and its excellent performance in enhancing the photostability of poly(p-phenylene sulfide)

U–TiO₂ is successfully coated with SiO₂ and subsequently well modified by APTES, and a core–shell structure exists on TiO₂@SiO₂ and TiO₂@SiO₂/APTES, which greatly reduces aggregation of the TiO₂ nanoparticles.

Scalable and Environmentally Benign Process for Smart Textile Nanofinishing

A major challenge in nanotechnology is that of determining how to introduce green and sustainable principles when assembling individual nanoscale elements to create working devices. For instance, textile nanofinishing is restricted by the many constraints of traditional pad-dry-cure processes, such as the use of costly chemical precursors to produce nanoparticles (NPs), the high liquid and energy consumption, the production of harmful liquid wastes, and multistep batch operations. By integrating low-cost, scalable, and environmentally benign aerosol processes of the type proposed here into textile nanofinishing, these constraints can be circumvented while leading to a new class of fabrics. The proposed one-step textile nanofinishing process relies on the diffusional deposition of aerosol NPs onto textile fibers. As proof of this concept, we deposit Ag NPs onto a range of textiles and assess their antimicrobial properties for two strains of bacteria (i.e., Staphylococcus aureus and Klebsiella pneumoniae). The measurements show that the logarithmic reduction in bacterial count can get as high as ca. 5.5 (corresponding to a reduction efficiency of 99.96%) when the Ag loading is 1 order of magnitude less (10 ppm; i.e., 10 mg Ag NPs per kg of textile) than that of textiles treated by traditional wet-routes. The antimicrobial activity does not increase in proportion to the Ag content above 10 ppm as a consequence of a "saturation" effect. Such low NP loadings on antimicrobial textiles minimizes the risk to human health (during textile use) and to the ecosystem (after textile disposal), as well as it reduces potential changes in color and texture of the resulting textile products. After three washes, the release of Ag is in the order of 1 wt %, which is comparable to textiles nanofinished with wet routes using binders. Interestingly, the washed textiles exhibit almost no reduction in antimicrobial activity, much as those of as-deposited samples. Considering that a realm of functional textiles can be nanofinished by aerosol NP deposition, our results demonstrate that the proposed approach, which is universal and sustainable, can potentially lead to a wide number of applications.

Hollow Casein-Based Polymeric Nanospheres for Opaque Coatings

Casein-based hollow polymeric sphere were fabricated through emulsifier-free polymerization coupled with alkali swelling approach. Hollow structure and nanoscale size of casein-based polymeric spheres were verified by TEM, AFM, SEM, and UV-vis spectra. The as-obtained hollow spheres were proved exhibiting superior opaque characteristic. Through adjusting the structural parameters, for example, MAA usages and MAA content in seed to core, sphere film showed tunable visible-light transmittance and antiultraviolet property. The formation mechanism of casein-based hollow sphere has been discussed in depth. Worth mentioning, the resultant hollow polymeric sphere can easily form films itself at room temperature, which would open a new possibility of designing opaque coatings in several fields, such as leather, packaging, paper making, biomedical, and special indoor coating applications.

Facile Fabrication of Multifunctional Hybrid Silk Fabrics with Controllable Surface Wettability and Laundering Durability

To obtain a hydrophobic surface, TiO2 coatings are deposited on the surface of silk fabric using atomic layer deposition (ALD) to realize a hierarchical roughness structure. The surface morphology and topography, structure, and wettability properties of bare silk fabric and TiO2-coated silk fabrics thus prepared are evaluated using scanning electron microscopy (SEM), field-emission scanning electron microscopy (FESEM), scanning probe microscope (SPM), X-ray diffraction (XRD), static water contact angles (WCAs), and roll-off angles, respectively. The surfaces of the silk fabrics with the TiO2 coatings exhibit higher surface roughnesses compared with those of the bare silk fabric. Importantly, the hydrophobic and laundering durability properties of the TiO2-coated silk fabrics are largely improved by increasing the thickness of the ALD TiO2 coating. Meanwhile, the ALD process has a litter effect on the service performance of silk fabric. Overall, TiO2 coating using an ALD process is recognized as a promising approach to produce hydrophobic surfaces for elastic materials.