Low Surface Energy Research Articles

Surface microstructure regulation of a novel N-CQDs /C3N4/Bi2WO6 self-cleaning synergistic photocatalytic degradation of NO coating

As well known, the apparent structure and chemical composition of self-cleaning photocatalytic coatings are crucial for their application. In this study, C3N4 with a large specific surface area was introduced into N-CQDs/Bi2WO6 to construct a highly catalytic active catalyst (CBW-0.5), which continuously degraded 57.7 % of NO. A robust self-cleaning photocatalytic coating (CCBW-B) was prepared by firmly bonding CBW-0.5 to the substrate through a layered spraying process. CBW-0.5 endowed CCBW-B with high catalytic activity, maintaining a degradation rate of 64.9 % for NO, and most of the surface organic dye contamination was degraded after 36 h. Due to the appropriate arrangement of low surface energy substances and micro/nano particles on the surface, CCBW-B with a graded cross network on the surface has contact angles (CA) of 156°/145° for water/olive oil, respectively. The influence of each component of CCBW-B on its photocatalytic and liquid repellent ability was studied, and the patterns for the differences in coating performance due to the changes in surface roughness structure caused by different layer distributions was discussed. In addition, the mechanism for the excellent performance of CCBW-B was explored using SEM, specific surface area, and the theory of the generation and distribution of air pockets. Finally, the durability and self-cleaning ability of CCBW-B were tested, and the synergistic mechanism of self-cleaning and photocatalysis was also provided.

Significantly enhanced corrosion resistance for Fe-based amorphous coatings via sealing treatment: Based on hybridisation and superhydrophobicity strategy

Based on the synergistic effect of hybridisation-superhydrophobicity, a simple and facile spraying method was used to achieve efficient sealing of Fe-based amorphous metallic coatings. In this paper, we employed rare-earth neodymium salts as inorganic sealant raw materials and loaded low surface energy fluorosilanes into epoxy resins to act as organic sealant raw materials. The surface structure and chemical composition of the sealing coatings were systematically characterised. The sealing mechanism as well as the anti-corrosion mechanism of the coating were investigated intensively. The results indicate that the superior corrosion resistance and self-cleaning ability of the sealed coating stems from the inorganic–organic-complex trinity effect: the corrosion inhibition effect of Nd oxide deposited during the inorganic sealing process, the shielding effect of the resin in the organic sealing, and the cross-linking and superhydrophobicity behaviour (liquid repellency effect) of the FDTES-Nd3+-Fe2+ complexes formed on the surface of the coating. This work provides valuable guidelines and insights for the design of subsequent corrosion-resistant and sealing coating.

Fog Harvesting Via Multistage Edge‐Effect Condensation

AbstractThe escalating global population and rapid industrialization have precipitated a severe freshwater scarcity crisis. To address this challenge, innovative strategies are essential to exploit unconventional water sources such as atmospheric vapor. This study proposes a novel approach integrating 3D printing technology with surface chemistry principles for atmospheric fog harvesting. The approach entails leveraging 3D printing technology, chosen for its cost‐effectiveness, unparalleled design flexibility to design intricate geometries, and time efficiency to fabricate cylindrical millimeter‐scale size vertical pillars. Harnessing the intricate interplay of surface phenomena, condensation preferentially occurs on the pillar tops due to surface phenomena. The pillars are imbued with nonadecane, a hydrocarbon renowned for its low surface energy characteristics ensures the uninterrupted progression of water droplet formation, coalescence, and seamless transportation, unveiling a symphony of molecular interactions at the microscale. The design demonstrates promising results, yielding an impressive yield of ≈3.956 g of water per hour from 1 cm2 area. Geometric discontinuities associated with parahydrophobic pillars amplify water harvesting via an edge effect. This study represents a significant step toward a more sustainable and technologically advanced solution for the global water crisis.

Fluorine containing diamond-like carbon coatings

Fluorine containing diamond-like carbon (DLC) coatings were obtained by CVD deposition using the destruction of gaseous hydrocarbons by a high-energy ion source with an anode layer. The chemical composition, structure, surface energy, mechano-tribological characteristics of the synthesized thin-film material were studied. It has been shown that the fluorine content in the deposited coatings reaches 31 at.%. It has been established that the presence of fluorine in the DLC coating promotes the formation of nanodispersed graphite-like structures. Fluorine containing coatings with a high content of sp2 hybridized carbon atoms and graphite fragments show a decrease in hardness. Such coatings have a very low coefficient of friction at the level of 0.03–0.07 due to the low surface energy, which can be reduced by 1.5 times compared to pure DLC. It has been established that different fluorine contents in thin-film diamond-like carbon material have different effects on the interaction of the DLC coating with polar/non-polar dielectrics. The research results can be used for the technology of producing solid lubricants in friction units of machines and mechanisms, and are also of interest for medicine, the food industry, the production of plastics, and chemical fibers as chemically inert and corrosion-resistant coatings.

Co-evolution of M23C6 precipitates and cavities in a boron-free Ni-based alloy GH3617 under high-temperature He ion irradiation: Effects on cavity swelling and mechanical properties

Ni-based alloys are promising materials for advanced nuclear reactors operating at high temperatures due to their exceptional resistance to high temperatures and corrosion. Understanding the synergy of phase stability and helium effects is crucial for assessing the long-term performance and reliability of these alloys in advanced nuclear reactors. This study has investigated the co-evolution behavior of M23C6 precipitates and cavities in a boron-free solid solution strengthened Ni-based alloy GH3617 under high-temperature He ion irradiation, and its impact on alloy swelling and mechanical properties, by He ion irradiation experiments with the highest fluence of 1 × 1017 He/cm2 up to 800 °C. Transmission Electron Microscopy (TEM) and Nanoindentation are employed to investigate microstructural evolution and mechanical properties, respectively. The findings show that at room temperature and 500 °C, cavities and dislocation loops were the dominant irradiation defects, whereas at 800 °C, the density of cavities and dislocations reduced while the formation of M23C6 precipitates increased. These precipitates act as effective trapping sites for He and point defect, leading to cavity formation at the interfaces or within the precipitates. Moreover, increased irradiation fluence accelerates the co-evolution process, resulting in an increase in the density and size of both precipitates and cavities, ultimately leading to enhanced swelling. The {111} planes are favored interfaces between intragranular M23C6 precipitates and the matrix due to their minimal misfit, while the preferred interface planes between cavities with octahedral or cubo-octahedral shapes and the precipitate/matrix are also {111}, owing to their lower surface energy as well. The co-evolution of cavities and precipitates was found to influence mechanical properties, resulting in an irradiation hardening effect at lower fluences, while softening at higher fluences. This study provides novel insights into the degradation mechanisms of Ni-based alloys under coupling effect of He and high-temperature irradiation.

Surfactant-enhanced chitosan coating extends postharvest shelf-life of Keitt mango

The surface properties of Keitt mango and wettability of chitosan (CH) coatings containing ethyl lauroyl arginate (LAE, an ionic surfactant), and sucrose monolaurate (SML, a non-ionic surfactant) were investigated. The Keitt mangoes were coated with different chitosan-based solutions and stored at room temperature (25.0 ± 0.6 °C) for 35 days. The Keitt mango surface had low surface energy (<100 mN/m) with high dispersive component (17.70 ± 1.49–22.86 ± 1.02 mN/m). SML and LAE surfactants significantly (P < 0.05) lowered the surface tension of the CH coating solution by 6.94, and 24.13 mN/m, respectively. As a result, the wettability of CH based coating on mangoes was improved to −68.37 ± 0.01 mN/m (CH-SML), and −30.29 ± 0.00 mN/m (CH-LAE) compared with CH (−76.45 ± 0.04 mN/m), resulting in smooth and homogeneous coatings. The storage test results indicated a significant reduction (P < 0.05) in disease incidence and weight loss by the CH-SML and CH-LAE coatings and the coated mangoes were firmer with lower pH values compared with the control. This study suggests that CH-LAE and CH-SML coatings can effectively extend the shelf-life of Keitt mangoes by 10 and > 15 days, respectively.

Investigation of the sintering behavior of nanoparticulate SiC by molecular dynamics simulation

Sintering is a valuable processing technique utilized to create bulk materials from powder compacts. In recent years, sintering has a garnered significant attention in the research community due to its versatility and applicability in various fields, including additive manufacturing. Herein, we investigate the sintering kinetics and mechanism of SiC nanoparticulate using molecular dynamics simulations. The surface morphology, microstructure, radial distribution function, mean square displacement, atomic displacement distribution, structural transformation, and diffusion coefficient are analyzed in detail. The free surface surrounding the neck undergoes a reconstruction to eventually reach an equilibrium dihedral angle. The neck rapidly grows and aligns with the surface, causing the SiC particle to transform from an original spherical shape into a twists shape. The concentration of shear stress results in a change of the local lattice structure from the face-centered cubic phase to amorphous phase in the surface. With an increasing sintering time, the dominant diffusion mechanism gradually shifts from surface diffusion to interface diffusion. This trend leads to a rise in the atomic migration, the consumption of interface energy, and the degree of particle fusion. Ultimately, the sintered SiC particles have the spherical shape, low surface energy, and stable structure. Additionally, the high mobility of melted atom causes a gradual dissolution of SiC particle into the large particle from the surface towards the interior. This process leads to high-altitude concentration structures that facilitate atomic migration. These results shed light on an atomic sintering mechanism in SiC nanoparticulate for applications in the preparation of nanostructured materials, and additive manufacturing.

Investigation of wettability and icing on the steel surface using laser surface treatment

Icing impairs normal functionality for a variety of industries and applications. Research on hydrophobic surfaces is being conducted to solve the icing problem. In this study, a hydrophobic surface was fabricated on SM490A using a nanosecond laser. The change in surface microstructure was observed. Hydrophilicity was immediately observed right after laser irradiation, and the contact angle increased over time, resulting in hydrophobicity. To explain the wettability conversion, X-Ray Photoelectron Spectroscopy (XPS) was used to observe changes in surface chemical composition and element bonding. It was observed that the level of and increased immediately after laser irradiation, resulting in surface oxidation. Since the presence of oxides has high surface energies, they contribute to super hydrophilic surfaces. Since the bond has low surface energy and the content of nonpolar bonds and increased over time, the contact angle subsequently increases over time. When the ice shape was observed after dropping a droplet on the surface, the higher contact angle specimen reduced the attached area. Therefore, the surface treatment using a nanosecond laser can produce a hydrophobic surface on the SM490A specimens so that it may solve ice adhesion problems.

Enhanced hydrophobic properties, wear and corrosion resistance of plasma electrolyte oxidation coatings on AZ31B magnesium alloys with addition of TiO2 nanoparticles

Nanocomposite coatings were fabricated on AZ31B magnesium alloy by means of plasma electrolyte oxidation (PEO) with the addition of TiO2 nanoparticles into the alkaline electrolyte, followed by low surface energy modification in the ethanol solution of lauric acid. The dual-layered nanocomposite PEO coatings composed of MgO, Mg2SiO4, anatase-TiO2, rutile-TiO2, and Mg2TiO4 were formed, and the TiO2 nanoparticles incorporated into the PEO coatings via both inertia and reactive modes. Besides, the penetration and adsorption of TiO2 nanoparticles created a distribution gradient in the coating thickness direction. The wear rate of the PEO coatings with TiO2 nanoparticles in 4 g/L was approximately 82 % lower than that of the bare substrate and approximately 39 % lower than that of the PEO coatings without TiO2 addition, respectively. The enhancement in wear resistance was due to the synergistic effect of the lower coefficient of friction (COF), the higher microhardness and the denser microstructure with finer micropores and less microcracks on the coatings than that of the TiO2-free coatings. Besides, the hydrophobic property was enhanced for the low surface energy modified PEO coatings with the addition of TiO2 nanoparticles in the electrolyte. Moreover, a significant enhancement in the corrosion resistance was achieved for the PEO coating with the addition of TiO2 nanoparticles in 4 g/L. It exhibited a higher corrosion inhibition efficiency and a lower corrosion rate than that in other concentrations and without TiO2 addition. The improvement in anti-corrosion property was originated from the formation of phases including TiO2 and Mg2TiO4 in the coating, and denser microstructure with better hydrophobic properties for the PEO coatings with TiO2 nanoparticles in 4 g/L compared with that in other concentrations. Accordingly, the hydrophobic, wear-resistant and corrosion-resistant PEO coatings with TiO2 nanoparticles exhibited significant advantages in the field of Mg alloys protection.

Design strategy of super tough hydrophobic bamboo framework composites with internal network entanglement reinforcing structure

The low strength and high hygroscopicity of natural bamboo limit its use in structural building materials. Herein, lignin and hemicellulose were partially removed from natural bamboo in order to create bamboo frameworks featuring well-aligned bamboo fibers. Subsequently, these bamboo frameworks (BF) are infused with epoxy resin (EP) modified with PDMS and subjected to hot-pressing to fabricate bamboo-epoxy composites (PDMS-EP/BF). The incorporation of flexible PDMS chains facilitated intermolecular chain entanglement, which inhibited crack propagation and improved the bonding between bamboo and EP. The findings of the research indicated that the PDMS-EP/BF composites exhibited a significant enhancement in flexural strength by 98%, modulus of elasticity by 129%, toughness by 399%, and tensile strength by 177% when compared to natural bamboo. Additionally, the modification led to a decrease in the surface energy of the composites, resulting in increased hydrostatic contact angle and imparting water repellency to the material. Compared to natural bamboo, PDMS-EP/BF has 309% higher water contact angle and 143% lower surface energy. In addition, large composites have been prepared and their interface strength was tested. The findings of the study offer insights into the potential enhancement of bamboo composites to achieve increased flexural strength, modulus, and toughness. This could expand the utilization and significance of bamboo in the realm of construction materials.

Fluorine-free superhydrophobic Ni/Mn-TiO2 composite coatings on carbon steel via one-step electrodeposition for enhanced durability and corrosion resistance

The application of superhydrophobic coatings on carbon steel (CS) surface represents an effective strategy for mitigating corrosion in these materials. This study presents the preparation of superhydrophobic Ni/Mn-TiO2 composite (SNMT) coatings on CS substrates through a facile one-step electrodeposition technique. The formation mechanism of SNMT coatings was meticulously analyzed under varying conditions of nanoparticle types and concentration levels. The inclusion of TiO2 nanoparticles, with an optimal additive concentration of 1 g, facilitated the formation of numerous low surface energy, cauliflower-like microstructures on CS interface. Surprisingly, the results indicate that SNMT coatings maintained commendable superhydrophobicity even post-exposure to superficial damages such as tape peeling, sandpaper wear, and knife-scratch, as evidenced by a static contact angle (CA) exceeding 158° and a sliding angle (SA) below 2°. Furthermore, the corrosion inhibition efficacy of SNMT coatings was quantitatively assessed via dynamic potential polarization curves in a simulated seawater environment. The results demonstrated that SNMT coatings exhibited excellent corrosion inhibition performance in simulated seawater solution, with a protection efficiency (PE) reaching 96.5%. In conclusion, superhydrophobic surfaces can effectively inhibit the penetration of corrosive liquids. The durability and robustness of such superhydrophobic surfaces advocate for their potential widespread application in enhancing the longevity and reliability of CS in corrosive environments.

Robust ZIF-8 based superhydrophobic coating with anti-icing, anti-corrosion, and substrate universality

The design of superhydrophobic materials based on zeolite imidazolate frameworks (ZIF) has attracted considerable attention due to their exceptional chemical stability, high specific surface area, and environmental friendliness. However, research in the fields of anti-corrosion and anti-icing remains in its infancy, and the mechanical stability of reported ZIF-based superhydrophobic surfaces is generally poor. In this study, we synthesized ZIF-8@PDA materials in an aqueous system and followed with stearic acid (STA) modification to achieve low surface energy, resulting in ZIF-8@PDA@STA. Subsequently, we applied a spray-coating method to sequentially construct WPU and ZIF-8@PDA@STA layer on aluminum alloy substrates, achieving a ZIF-8@PDA@STA/WPU superhydrophobic coating with exceptional mechanical stability. This coating retained its superhydrophobicity even after 5600 cm of abrasion distance. Furthermore, results from surface wettability, electrochemical and anti-icing tests demonstrated that the coated aluminum alloy exhibited excellent interfacial non-wetting, self-cleaning, anti-fouling, and significantly enhanced corrosion resistance and delayed icing properties. Additionally, the facile preparation of this coating on various substrates facilitates the large-scale application of such materials. The construction of this multifunctional ZIF-8 based superhydrophobic coating is expected to greatly expand the application of ZIF materials across diverse fields.

Mechanically durable plant-based composite surface towards enhanced antifouling properties

The biofouling adhering to underwater facilities has a negative impact on the environment, energy, and economic development. However, conventional anti-adhesion organic silicon and organic fluorine materials often have poor adhesion properties and mechanical stability when combined with substrates. This work presents a novel strategy for preparing composite antifouling coatings that low surface energy plant-based carnauba wax (CW) covering through rough substrates and chemically bond with flexible polydimethylsiloxane (PDMS) oligomers or polymers. The CW coating adheres strongly to the substrate owing to the mobility of the liquated CW, which flows into the micro-nano structure of the substrate and solidifies on the solid surface. The polymerization reaction of (PDMS) oligomers compounded the coating, thereby creating a composite coating with superior lubricating and antifouling properties. This distinctive bonding process imbued the coating with exceptional characteristics, including remarkable mechanical stability in destructive tests as well as an impressive ability to repel fouling, such as protein attachment, bacterial adhesion, diatom deposition, and biofilm formation. This work systematically investigated the impact of the composition and structure of composite materials on their mechanical stability and resistance to fouling, and developed high-performance antifouling coatings in the real world.

Sm-MOF decorated cotton for efficient on-demand oil-water separation and organic pollutants removal

Complex wastewater containing oil–water and contaminant mixtures is a constant threat to ecosystems and public health. However, efficient water–oil separation and water treatment are required, with a preference for simple but universal matrices for possible large-scale applications. Herein, effective oil–water separation and organic pollutant removal are simultaneously realized on cotton balls decorated with polydimethylsiloxane combined with a samarium metal–organic framework. Cotton balls containing polydimethylsiloxane (10 %) and Sm-MOF (Synthesis temperature was 110 ℃, 15 mg/L) were successfully prepared by a simple precipitation method, with a high water contact angle of 150.75 ± 1.1°. After pre-wetting with a low surface energy solution, the modified cotton was endowed with repeatable super-wetting transitions between superhydrophobic/superoleophilic and superhydrophilic/underwater superoleophobic properties. In addition to on-demand separations of immiscible oil–water mixtures at a rate of 95 %, water-in-oil emulsions could be separated by the addition of different surfactants. The mechanism of demulsification of the treated cotton ball was studied based on the type of emulsifier and the results of emulsified oil separation. Cotton balls modified with 10 % PDMS and Sm-MOF (Synthesis temperature was 140 °C; 15 mg/L) showed higher adsorption capacity compared to pure cotton balls, adsorbing about 98.7 % of Eriochrome Black T within 2 h. Cotton balls modified by PDMS and Sm-MOF are an effective, safe and green material with promising applications in the simultaneous separation of oil–water mixtures and removal of organic pollutants from water systems.

Surface etching-reconstruction effectively suppresses icing in jet fuel pipeline

In extreme weather, icing in aircraft fuel systems poses a serious threat to flight safety. Moisture in fuel can freeze inside pipes at high altitudes, risking engine operation and performance. This study explores the use of superhydrophobic technology to prevent icing. Aerospace-grade aluminum alloy (6061) was chemically etched with FeCl3 to create rough micro and nano structures. The surface was then modified with low surface energy perfluoropolyether (PFPE) to form a superhydrophobic coating. Tests showed that a 1.0 wt% PFPE coating exhibited excellent superhydrophobic and oleophobic properties, with a water contact angle of 154.79° and a jet fuel (RP-3) contact angle of 150.13°. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR) analyses confirmed the presence of C-F3 and C-F2 bonds. The electrochemical corrosion resistance test shows that the coating has good corrosion resistance and the corrosion resistance rate is 0.61 mm/a. The coating also demonstrated outstanding waterproof performance, resisting grease and stain adhesion under jet fuel immersion. This approach offers a promising solution for surface protection and functional material design. Future research will further optimize its performance and explore broader applications.

Synergetic integration of photothermal and self-cleaning features in a composite phase change material based on layered double hydroxides and polypyrrole

Composite phase change materials (PCMs) with photothermal functionality play a crucial role in efficiently storing and utilizing solar energy. However, the challenge of effectively removing of contaminants on photothermal conversion coatings has long puzzled researchers. In this study, we propose a novel approach to enhancing both photothermal conversion performance and self-cleaning properties of wood-based composite phase change materials, ultimately facilitating the sustainable and effective utilization of solar energy. The method utilized metal-organic frameworks (MOFs) as a precursor to form rough layered double hydroxides (LDH) on the wood surface through hydrolysis-induced exchange. Subsequently, polypyrrole (PPy) was deposited through vapor phase onto the LDH, and paraffin wax (PW) is utilized as the phase change material to prepare a novel composite phase change material. This modified wood structure facilitates leak-proof PW encapsulation and effective heat storage (167.6 J/g). PPy acts as a proficient photothermal converter and improves the composite material's heat transfer efficiency by establishing thermal conduction pathways, resulting in an 87.4 % enhancement in thermal conductivity compared to pure PW. The rough surface of LDH promotes multiple light reflections and scattering within the material, leading to increased light absorption by the PPy coating and achieving a photothermal conversion efficiency of up to 96.4 %. Furthermore, the high roughness of the LDH layer combined with the low surface energy of PW imparts superhydrophobic self-cleaning properties to the material, ensuring sustained effectiveness of the photothermal conversion coating over time. This research presents a viable approach for maintaining the cleanliness and efficiency of solar energy systems.

Visualizing dynamic alterations of vitreous viscosity during elevated intraocular pressure in glaucoma with a Near-infrared/Magnetic resonance imaging dual-modal nanoprobe

Glaucoma is a chronic progressive disease leading to irreversible visual impairment and blindness. High intraocular pressure (IOP) resulting from abnormally high outflow resistance is a major risk factor for glaucoma development, however, it is unclear how IOP elevation influences the structure and function of the retina and the optic nerve via vitreous humor located between the lens and retina in the eye. To understand vitreous biomechanical and stimulus response toward IOP elevation, we developed a novel near-infrared (NIR)/MRI dual-modal nanoprobe, DTA/P-NCA/17F@Co, which is composed of N, N-dimethyl-4(thien-2-yl)-aniline group (DTA) as NIR fluorophore and the fluorine-based polyamino acid cobalt nanoparticles (P-NCA/17F@Co) as T2 contrast agent. These nanoprobes exhibit good biocompatibility, low surface energy characteristics, and viscosity-responsive NIR emission and T2 relaxation values. The intrinsic viscosity-sensitivemechanismof nanoprobes was ascribed to constrained molecular motion in high-viscosity vitreous chamber, which causes enhanced fluorescence emission and shortened T2 relaxation times. By using its ability for dual-modal visualization of viscosity, we achieved non-invasive in vivo monitoring the changes in vitreous viscosity during elevated IOP in a glaucoma rat model. In vivo experiments validated that vitreous viscosity is very strongly correlated with IOP elevation induced by glaucoma, much earlier than structural and functional change in the retina. Our findings revealed that IOP elevation induced the increase of vitreous viscosity, indicating that monitoring vitreous viscosity is key to the glaucoma model. This study not only provides versatile nanoprobes for dual-modal visualization of biomechanical properties of the vitreous humor in its native environment, but also shows great potential in the early diagnosis of glaucoma.

Surface structures and wettability: Their roles in enhancing nucleate boiling heat transfer of refrigerants

Nucleate boiling is an effective heat transfer mechanism. Previous studies have demonstrated that modifying surface structure or wettability can independently improve nucleate boiling efficiency; however, the combined effects and optimal modification sequence remain underexplored. This research aims to comprehensively analyze the influence of surface structure and wettability on the nucleate boiling heat transfer performance of refrigerants. Different surface structures and wettability were prepared using surface polishing, laser ablation, mechanical cutting, and a combination that involved initially employing laser ablation, followed by the application of chemical etching, and finishing with the treatment using materials possessing low surface energy. The static contact angles on these surfaces were measured via the capillary rise method, followed by pool boiling experiments and bubble behavior visualization. The results show that increasing surface wettability can enhance bubble departure frequency and capillary wicking, thereby improving critical heat flux and heat transfer coefficient. The key to optimizing surface modification to enhance critical heat flux involves constructing alternating high and low nucleation core regions to reduce interactions between bubbles; for enhancing heat transfer coefficient, the key lies in constructing compact nanoscale structures that expand the heat transfer and nucleation area, followed by improving wettability.

Robust, intelligent photochromic cotton fabrics with superamphiphobicity and expedient UV detection ability

Multifunctional photochromic cotton fabrics have enormous application potential in our daily lives, but still suffer from poor durability, slow coloration, tedious fabrication process, and short service life. The hydrophilic and polysaccharide characteristics of cotton fabrics make them vulnerable to bacteria adhesion and proliferation. Herein, intelligent photochromic cotton fabrics featured with durable superamphiphobicity are fabricated by in situ growth of ZIF-8 nanoparticles encapsulating spirooxazine (SP) photochromic dyes on the fabric surface, followed by low surface energy treatment using a fluorocarbon resin (FR) via a dip-coating method. The resultant SP@ZIF-8/FR cotton fabrics exhibit superamphiphobicity with contact angles of over 150° to both water and oils (surface tension ≥30 mN/m). When exposed to UV light, the fabric rapidly changes its color from white to blue within 10 s and fades in 2 min under visible room light. The developed SP@ZIF-8/FR coating is durable against numerous damages in daily usage, such as machine laundry, abrasion and UV irradiation, without losing photochromic and superamphiphobic properties. The high durability and excellent reversible color response allow the coated fabric to intuitively and quantitatively monitor outdoor UV intensity. Owing to the presence of ZIF-8, the treated fabrics also show excellent antibacterial property with antibacterial rates of over 99 % against both E. coli and S. aureus. The developed fabric coating can be engineered to visually assess the UV intensity in the outdoor environment.

Structure, Morphology and Surface Properties of α-Lactose Monohydrate in Relation to its Powder Properties

The particulate properties of α-lactose monohydrate (αLMH), an excipient and carrier for pharmaceuticals, is important for the design, formulation and performance of a wide range of drug products. Here an integrated multi-scale workflow provides a detailed molecular and inter-molecular (synthonic) analysis of its crystal morphology, surface chemistry and surface energy. Predicted morphologies are validated in 3D through X-ray diffraction contrast tomography. Interestingly, from aqueous solution fastest growth is found to lie along the b-axis, i.e. the longest unit cell dimension of the αLMH crystal structure reflecting the greater opportunities for solvation on the prism compared to the capping faces leading to their slower relative growth rates. The tomahawk morphology reflects the presence of β-lactose which asymmetrically binds to the capping surfaces creating a polar morphology. The crystal lattice energy is dominated by van der Waals interactions (between lactose molecules) with electrostatic interactions contributing the remainder. Predicted total surface energies are in good agreement with those measured at high surface coverage by inverse gas chromatography, albeit their dispersive contributions are found to be higher than those measured. The calculated surface energies of crystal habit surfaces are not found to be significantly different between different crystal surfaces, consistent with αLMH's known homogeneous binding to drug molecules when formulated. Surface energies for different morphologies reveals crystals with the elongated crystal morphologies have lower surface energies compared to those with a triangular or tomahawk morphologies, correlating well with literature data that the surface energies of the lactose carriers are inversely proportional to their aerosol dispersion performance.