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1.
Environ Sci Technol ; 2024 Jul 20.
Article in English | MEDLINE | ID: mdl-39031076

ABSTRACT

Ice can serve as a significant temporary repository and conveyance mechanism for microplastics (MPs). MPs present in the water column can become entrapped within developing ice formations, subsequently being sequestered and transported by ice floes. With changing temperatures, MPs stored in ice can be released back into the environment, while freezing conditions can alter the properties of MPs, ultimately affecting the fate of MPs in the environment. Freezing of MPs in freshwater ice results in the aggregation of MP particles due to physical compression, leading to an increase in particle size once the MPs are released from the ice. The freezing-induced aggregation enhances buoyancy effects, accelerating the settling/rising velocity of MPs in water. Additionally, freezing can lead to enhanced surface wetting alterations, thus improving the dispersion of hydrophobic MPs. The presence of salt in the water can mitigate the effect of freezing on MPs due to the formation of a brine network within the ice structure, which reduces the pressure on MPs entrapped by ice. In cold regions, numerous MPs undergo freezing and thawing, re-entering the water column.

2.
Adv Mater ; : e2402893, 2024 Jun 07.
Article in English | MEDLINE | ID: mdl-38848582

ABSTRACT

The ability of water droplets to move freely on superrepellent surfaces is a crucial feature that enables effective liquid repellency. Common superrepellent surfaces allow free motion of droplets in the Cassie state, with the liquid resting on the surface textures. However, liquid impalement into the textures generally leads to a wetting transition to the Wenzel state and droplet immobilization on the surface, thereby destroying the liquid repellency. This study reports the creation of a novel type of superrepellent surface through rational structural control combined with liquid-like surface chemistry, which allows for the free movement of water droplets and effective repellency in both the Cassie and Wenzel states. Theoretical guidelines for designing such surfaces are provided, and experimental results are consistent with theoretical analysis. Furthermore, this work demonstrates the enhanced ice resistance of the dually-mobile superrepellent surfaces, along with their distinctive self-cleaning capability to eliminate internal contaminants. This study expands the understanding of superrepellency and offers new possibilities for the development of repellent surfaces with exceptional anti-wetting properties.

3.
J Colloid Interface Sci ; 664: 727-735, 2024 Jun 15.
Article in English | MEDLINE | ID: mdl-38492374

ABSTRACT

Transparent protective coatings capable of preventing fog and dust accumulation have broad application prospect in photovoltaic systems, optical devices and consumer electronics. Although a number of superhydrophobic coatings have been developed for self-cleaning purpose over the past three decades, there is still a lack of surfaces that can simultaneously possess high transparency, remarkable superhydrophobicity, and excellent fog and dust resistance. In this study, we have prepared surfaces featuring sub-wavelength nanofiber cluster structures through a facile plasma etching method, and further modified the surface with liquid-like perfluoropolyether (PFPE) brushes. The prepared PFPE modified nanofibrous surface (PFPE-NS) exhibits superior optical transparency (transmittance 90.4 % ± 0.7 %) and water repellency, with a water contact angle as high as 171.0° ± 0.6° and sliding angle down to 0.5° ± 0.1° (5 µL). More importantly, benefitted from the nanofiber cluster structures and the slippery liquid-like surface chemistry, the adhesion and accumulation of fog droplets and dust particles on PFPE-NS is greatly inhibited. As a consequence, PFPE-NS can keep excellent optical clearness after 2 h fogging test and maintain an average transmittance above 87 % after 24 h dusting test. Our study provides a promising strategy through constructing liquid-like nanofibrous coating for optical protection that could be applicable in practical rainy, foggy, and dusty environments.

4.
ACS Nano ; 18(8): 6359-6372, 2024 Feb 27.
Article in English | MEDLINE | ID: mdl-38363638

ABSTRACT

On-demand droplet transportation is of great significance for numerous applications. Although various strategies have been developed for droplet transportation, out-of-surface three-dimensional (3D) transportation of droplets remains challenging. Here, a versatile droplet transportation strategy based on magnetic-actuated jumping (MAJ) of droplets on superhydrophobic grooved surfaces (SHGSs) is presented, which enables 3D, remote, and precise manipulation of droplets even in enclosed narrow spaces. To trigger MAJ, an electromagnetic field is utilized to deform the droplet on the SHGS with the aid of an attached magnetic particle, thereby the droplet acquires excess surface energy. When the electromagnetic field is quickly removed, the excess surface energy is partly converted into kinetic energy, allowing the droplet to jump atop the surface. Through high-speed imaging and numerical simulation, the working mechanism and size matching effect of MAJ are unveiled. It is found that the MAJ behavior can only be observed if the sizes of the droplets and the superhydrophobic grooves are matched, otherwise unwanted entrapment or pinch-off effects would lead to failure of MAJ. A regime diagram which serves as a guideline to design SHGSs for MAJ is proposed. The droplet transportation capacities of MAJ, including in-surface and out-of-surface directional transportation, climbing stairs, and crossing obstacles, are also demonstrated. With the ability to remotely manipulate droplets in enclosed narrow spaces without using any mechanical moving parts, MAJ can be used to design miniaturized fluidic platforms, which exhibit great potential for applications in bioassays, microfluidics, droplet-based switches, and microreactions.

5.
Lab Chip ; 24(6): 1658-1667, 2024 Mar 12.
Article in English | MEDLINE | ID: mdl-38299611

ABSTRACT

Super-liquid-repellent surfaces capable of preventing wetting with various liquids have tremendous application. However, high liquid repellency relies on surface texturing to minimize the solid-liquid interfacial contact, which generally results in impaired interface robustness and pressure resistance. Consequently, the surface tends to undergo a Cassie-Baxter to Wenzel wetting transition and loses liquid repellency under high-velocity liquid impact, especially for low-surface-tension liquids. Here, surface design through combining the nanoscale effect and doubly reentrant structure is demonstrated to solve the above challenge. By utilizing a facile colloidal lithography process, robust liquid repellent surfaces featuring nanoscale doubly reentrant (NDR) structures are constructed. The nanoscale features ensure sufficient triple contact line density at a low solid-liquid contact fraction to enhance the capillary force for liquid suspension. In conjunction with the doubly reentrant topography that maximizes the upward component of capillary force, such NDR surfaces enable an extremely robust solid-liquid-gas composite interface. As a result, the prepared NDR surface maintain excellent repellency upon high-velocity impact of various liquids, including ethylene glycol drops with a Weber number (We) above 306 and ethanol drops with a We of 57. The above findings can help the development of super-liquid-repellent surfaces applicable to harsh conditions of high-velocity liquid impact or high hydrostatic pressure.

6.
7.
Foods ; 12(17)2023 Aug 29.
Article in English | MEDLINE | ID: mdl-37685184

ABSTRACT

Chronic high-fat diet intake may induce obesity and increase the risk of metabolic syndrome. The pomace of grape (Vitis vinifera L.) is rich in polyphenols, which are candidates for anti-obesity therapy. The present study aimed to investigate the effects of Dunkelfelder grape seed extract (GSE) and grape peel extract (GPE) on lipid and energy metabolism disorders in mice maintained on a high-fat diet (HFD). Male nine-week C57BL/6J mice were randomly assigned to one of four groups, namely, the normal chow diet (ND), HFD, HFD plus GSE (400 mg/kg BW) administered by oral gavage, or HFD plus GPE (400 mg/kg BW) administered by oral gavage. There were eight mice per group, and the experiment was 14 weeks in duration. The results showed that GSE and GPE treatments did not affect energy intake in mice on a high-fat diet, but body weight gain was 24.5% and 17.3% lower in the GSE- and GPE-treated mice than in the HFD group, respectively. They also decreased blood triglyceride (TG), total cholesterol (TC), and fasting blood glucose levels and increased high-density lipoprotein cholesterol (HDL-C). In addition, GSE and GPE reduced adipose tissue weight and excessive lipid droplet accumulation in the adipocytes. The metabolic chamber test showed that the GSE and GPE treatments enhanced oxygen consumption, carbon dioxide production, and heat release while decreasing the respiratory exchange rate (RER). This suggests that GSE and GPE augmented fuel oxidation and energy generation and increased the proportion of lipids being utilized in energy metabolism. GSE and GPE also upregulated the genes controlling lipolysis and downregulated those controlling lipogenesis in adipose tissues. Moreover, they significantly increased the expression levels of the genes regulating thermogenesis in BAT, eWAT, and iWAT, and mitochondrial biogenesis in all three types of adipose tissue. In conclusion, the present study empirically demonstrated that GSE and GPE enhance body fat utilization by augmenting lipid and energy metabolism and could, therefore, ameliorate high-fat diet-induced obesity.

8.
Environ Sci Technol ; 57(33): 12180-12190, 2023 08 22.
Article in English | MEDLINE | ID: mdl-37556349

ABSTRACT

Reducing greenhouse gas emissions from maritime transport is an urgent topic. Some regional emissions trading systems (ETSs), buoyed by the globalized market-based measures (MBMs) plan of the International maritime organization, have initially assessed the feasibility of including maritime emissions under compliance obligations. However, including maritime emissions (which are interjurisdictional) in the existing ETSs is controversial, and globalized maritime MBMs remain elusive. Therefore, this study designed a joint bilateral maritime carbon market (BMCM) model based on the European ETS (EU-ETS) and Quebec ETS (QC-ETS). The carbon costs, speed optimization, and marginal abatement costs of three container routes under BMCM were analyzed. The results show that this Euro-American linkage achieves adequate emission coverage on specific routes and generates acceptable carbon costs for charterers. This study yields a positive result for the equal division of ETSs' exercising competence in cross-regional maritime transport and provides evidence for sector-specific ETS links based on quantitative analysis.


Subject(s)
Carbon , Greenhouse Gases , Costs and Cost Analysis , China
9.
Nat Rev Chem ; 7(2): 123-137, 2023 Feb.
Article in English | MEDLINE | ID: mdl-37117914

ABSTRACT

Liquid-repellent surfaces, especially smooth solid surfaces with covalently grafted flexible polymer brushes or alkyl monolayers, are the focus of an expanding research area. Surface-tethered flexible species are highly mobile at room temperature, giving solid surfaces a unique liquid-like quality and unprecedented dynamical repellency towards various liquids regardless of their surface tension. Omniphobic liquid-like surfaces (LLSs) are a promising alternative to air-mediated superhydrophobic or superoleophobic surfaces and lubricant-mediated slippery surfaces, avoiding fabrication complexity and air/lubricant loss issues. More importantly, the liquid-like molecular layer controls many important interface properties, such as slip, friction and adhesion, which may enable novel functions and applications that are inaccessible with conventional solid coatings. In this Review, we introduce LLSs and their inherent dynamic omniphobic mechanisms. Particular emphasis is given to the fundamental principles of surface design and the consequences of the liquid-like nature for task-specific applications. We also provide an overview of the key challenges and opportunities for omniphobic LLSs.

10.
J Clin Lab Anal ; 37(4): e24847, 2023 Apr.
Article in English | MEDLINE | ID: mdl-36755361

ABSTRACT

BACKGROUNDS: Human epididymis protein-4 (HE-4) is a commonly used biomarker for diagnosing ovarian cancer. Elevated HE-4 has also been observed in various benign conditions including chronic kidney disease (CKD); however, generalizability and statistical power of previous studies have been limited by small sample sizes. MATERIALS AND METHODS: We conducted a retrospective study that included 80 pathologically confirmed ovarian cancer patients, 641 CKD patients, and 2661 healthy controls. Serum HE-4 and several renal function parameters were collected and compared between the three groups. Correlation analysis was conducted to evaluate the relationship between HE-4 and renal function parameters. A receiver operating characteristic curve was established to evaluate its diagnostic performance. RESULTS: CKD patients had the highest levels of HE-4, with a median of 193.00 pmol/L, while the median in ovarian cancer patients was 90.82 pmol/L. HE-4 levels also increased with CKD progression, and Spearman's rank correlation showed that HE-4 had a strong correlation with renal function parameters in CKD patients. Furthermore, HE-4 exhibited a satisfactory diagnostic performance in both differentiating CKD patients and controls as well as stage 2 CKD patients and controls. CONCLUSION: HE-4 can be used as an alternative biomarker for diagnosing CKD as it is less affected by several preanalytical factors. Nevertheless, in clinical practice, elevated HE-4 requires taking both CKD and ovarian cancer into consideration.


Subject(s)
Ovarian Neoplasms , Renal Insufficiency, Chronic , Humans , Female , Retrospective Studies , Ovarian Neoplasms/diagnosis , Biomarkers , ROC Curve
11.
Environ Sci Technol ; 57(8): 3176-3186, 2023 02 28.
Article in English | MEDLINE | ID: mdl-36780450

ABSTRACT

Sea ice can serve as a temporary sink for microplastics (MPs), and thus, it too can function as a secondary source of and transport medium for MPs. This study aimed to explore the effect of various MP properties and environmental characteristics on the entrainment and enrichment of MPs in ice under varying turbulence conditions. It was found that high rotation speed in freshwater distinctively enhanced the entrainment of hydrophobic MPs in ice, this being attributable to the combined effects of frazil ice and air bubbles. The hydrophobic nature of these MPs caused them to be attracted to the water/air or water/ice interface. However, in saline water, high turbulence inhibited the entrainment of all of the MP types under study. The ice crystals formed a loose structure in saline water instead of congealing, and this allowed the exchange of MPs between ice and water, leading to the rapid expulsion of MPs from the ice. The enrichment factors of all the MPs under study increased in calm saline water compared to in calm freshwater. The results revealed that the entrainment and enrichment of MPs in ice can be critical pathways affecting their fate in cold regions.


Subject(s)
Microplastics , Water Pollutants, Chemical , Plastics , Water Pollutants, Chemical/analysis , Environmental Monitoring , Fresh Water
12.
Crit Rev Food Sci Nutr ; : 1-17, 2022 Nov 17.
Article in English | MEDLINE | ID: mdl-36398354

ABSTRACT

Grape pomace is the most important residual after wine making, and it is considered to be a very abundant source for the extraction of a wide range of polyphenols. These polyphenols exhibit a variety of bioactivities, such as antioxidant, anti-inflammatory, and anti-cancer. They are also beneficial in alleviating metabolic syndrome and regulating intestinal flora, etc. These health effects are most likely contributed by polyphenol metabolite, which are formed by the grape pomace phenolics after a complex metabolic process in vivo. Therefore, understanding the phenolic composition of grape pomace and its metabolism is the basis for an in-depth study of the biological activity of grape pomace polyphenols. In this paper, we first summarize the composition of phenolics in grape pomace, then review the recent studies on the metabolism of grape pomace phenolics, including changes in phenolics in the gastrointestinal tract, their pharmacokinetics in the systemic circulation, the tissue distribution of phenolic metabolites, and the beneficial effects of metabolites on intestinal health, and finally summarize the effects of human health status and dietary fiber on the metabolism of grape polyphenols. It is expected to provide help for the in-depth research on the metabolism and biological activity of grape pomace polyphenol extracts, and to provide theoretical support for the development and utilization of grape pomace.

13.
Research (Wash D C) ; 2022: 9850316, 2022.
Article in English | MEDLINE | ID: mdl-36258844

ABSTRACT

Driven by the ever-increasing demand for fingerprint-resistant techniques in modern society, numerous researches have proposed to develop innovative antifingerprint coatings based on superhydrophobic/superoleophobic surface design. However, whether superhydrophobic/superoleophobic surfaces have favorable repellency to the microscopic fingerprint is in fact an open question. Here, we establish a reliable method that enables evaluating the antifingerprint capability of various surfaces in a quantitative way. We show that superhydrophobicity is irrelevant with fingerprint repellency. Regarding superoleophobic surfaces, two distinct wetting states of microscopic fingerprint residues, i.e., the "repellent" and the "collapsed" states, are revealed. Only in the "repellent" state, in which the fingerprint residues remain atop surface textures upon being pressed, superoleophobic surfaces can bring about favorable antifingerprint repellency, which correlates positively with their receding contact angles. A finger-deformation-dependent intrusion mechanism is proposed to account for the formation of different fingerprint wetting states. Our findings offer important insights into the mechanism of fingerprint repellency and will help the design of high-performance antifingerprint surfaces for diverse applications.

14.
Sci Total Environ ; 840: 156657, 2022 Sep 20.
Article in English | MEDLINE | ID: mdl-35709991

ABSTRACT

Understanding the emission characteristics in the evolution of private vehicle fleet composition has become a key issue to be addressed to develop appropriate emission mitigation strategies in transportation sector. In this study, the influence of such evolution on on-road emissions was investigated based on a comprehensive dataset encompassing vehicle fleet composition, demographic, economic, and energy features from a representative small-medium automotive city in North America. The decoupling analysis was carried out to assess the dynamic linkage between environmental pressure exerted by the transportation sector and economic growth at both city level and national level in North America. We also developed an approach that supports the long-term traffic-related air pollutant prediction and investigated the potential influence on urban air quality. A sharp upward trajectory was observed in the quantity of SUVs from 2001 to 2018, gradually replacing the dominance of the quantity of four-door cars. There was a significant shift in the GHG emissions emitted from vehicle types used for passenger transport: emissions from SUVs and trucks rose by 374.0% and 69.3%, respectively, whereas emissions from four-door cars, two-door cars, station wagons, and vans all decreased. The changes in vehicle composition, along with the steady trend in GHG emissions from private fleet and decrease in on-road air pollutant concentrations found in Regina, were a response to the establishment of federal fuel economy standards and improved fuel economy. Relative decoupling was observed in aggregate for Regina and Canada in most of the years while both experienced economic downturns and increases in environmental pressure in the form of emissions from 2014 to 2015. The predicted results also demonstrate the high capability of XGboost machine learning algorithm in predicting on-road air pollutant concentrations of CO, PM2.5, and NOX.


Subject(s)
Air Pollutants , Air Pollution , Air Pollutants/analysis , Air Pollution/analysis , Cities , Environmental Monitoring/methods , Motor Vehicles , Vehicle Emissions/analysis
15.
Mar Pollut Bull ; 180: 113779, 2022 Jul.
Article in English | MEDLINE | ID: mdl-35635887

ABSTRACT

The rapid growth in the global production of organophosphate esters (OPEs) has resulted in their high environmental concentrations. The low removal rate of OPEs makes the effluents of wastewater treatment plants be one of the major sources of OPEs. Due to relatively high solubility and mobility, OPEs can be carried to the coastal environment through river discharge and atmospheric deposition. Therefore, the coastal environment can be an important OPE sink. Previous studies have shown that OPEs were widely detected in coastal atmospheres, water, sediments, and even aquatic organisms. OPEs can undergo various environmental processes in the coastal environment, including adsorption/desorption, air-water exchange, and degradation. In addition, bioaccumulation of OPEs was observed in coastal biota but current concentrations would not cause significant ecological risks. More efforts are required to understand the environmental behaviors of OPEs and address resultant environmental and health risks, especially in the complicated environment.


Subject(s)
Environmental Monitoring , Flame Retardants , China , Environmental Monitoring/methods , Esters , Flame Retardants/analysis , Organophosphates , Rivers , Water
16.
Chemosphere ; 288(Pt 3): 132628, 2022 Feb.
Article in English | MEDLINE | ID: mdl-34687682

ABSTRACT

The released oil can affect the vulnerable shoreline environment if the oil spills happen in coastal waters. The stranded oil on shorelines is persistent, posing a long-term influence on the intertidal ecosystem after weathering. Therefore, shoreline cleanup techniques are required to remove the oil from the shoreline environment. In this study, a new shoreline cleanup initiative using chitosan/rhamnolipid (CS/RL) complex dispersion with pH-stimulus response was developed for oiled sand cleanup. The results of factorial and single-factor design revealed that the CS/RL complex dispersion maintained high removal efficiency for oiled sand with different levels of oil content in comparison to using rhamnolipid alone. However, the increase of salinity negatively affected the removal efficiency. The electrostatic screening effect of high ionic strength can hinder the formation of the CS/RL complex, and thus reduce removal efficiency. The pH-responsive characteristic of chitosan allows the easy separation of water and oil in washing effluent. The chitosan polyelectrolytes aggregated and precipitated due to the deprotonation of amino groups by adjusting the pH of the washing effluent to above 8. The microscope image demonstrated that the chitosan aggregates wrapped around the oil droplets and settled to the bottom together, thus achieving oil-water separation. Such pH-stimulus response may help achieve an easy oil-water separation after washing. These findings have important implications for developing the new strategies of oil spill response.


Subject(s)
Chitosan , Petroleum Pollution , Petroleum , Water Pollutants, Chemical , Ecosystem , Glycolipids , Hydrogen-Ion Concentration , Petroleum Pollution/analysis , Sand , Water Pollutants, Chemical/analysis
17.
Adv Sci (Weinh) ; 8(23): e2103182, 2021 12.
Article in English | MEDLINE | ID: mdl-34693657

ABSTRACT

Magnetically responsive structured surfaces enabling multifunctional droplet manipulation are of significant interest in both scientific and engineering research. To realize magnetic actuation, current strategies generally employ well-designed microarrays of high-aspect-ratio structure components (e.g., microcilia, micropillars, and microplates) with incorporated magnetism to allow reversible bending deformation driven by magnets. However, such magneto-responsive microarray surfaces suffer from highly restricted deformation range and poor control precision under magnetic field, restraining their droplet manipulation capability. Herein, a novel magneto-responsive shutter (MRS) design composed of arrayed microblades connected to a frame is developed for on-demand droplet manipulation. The microblades can perform two dynamical transformation operations, including reversible swing and rotation, and significantly, the transformation can be precisely controlled over a large rotation range with the highest rotation angle up to 3960°. Functionalized MRSs based on the above design, including Janus-MRS, superhydrophobic MRS (SHP-MRS) and lubricant infused slippery MRS (LIS-MRS), can realize a wide range of droplet manipulations, ranging from switchable wettability, directional droplet bounce, droplet distribution, and droplet merging, to continuous droplet transport along either straight or curved paths. MRS provides a new paradigm of using swing/rotation topographic transformation to replace conventional bending deformation for highly efficient and on-demand multimode droplet manipulation under magnetic actuation.

18.
J Contam Hydrol ; 242: 103852, 2021 10.
Article in English | MEDLINE | ID: mdl-34214919

ABSTRACT

Alberta has over 70% of total irrigated land in Canada and 13 irrigation districts are mainly located along the rivers in southern Alberta. The runoff and irrigation return flow can carry excess nutrients, pesticides, and sediments, which adversely affect the river water quality. In the present study, the comprehensive spatiotemporal analysis of land use pattern and stream water quality in southern Alberta was conducted. The water quality monitoring on the South Saskatchewan River watershed within Alberta showed that most water quality indicators did not significantly change between 2003 and 2017. Land use maps demonstrated significant urban expansion and cropland decline in the study area from 2005 to 2015, while the irrigation area increased. Correlation analysis and redundancy analysis revealed that cropland, built-up land, and native grassland were three land use types that were positively correlated with water quality indicators. Stronger correlations between nitrogen concentration and built-up land were found in dry seasons compared with wet seasons. According to the results of cluster analysis, higher water quality indicator concentrations could be observed in groups with a higher proportion of cropland and built-up land. Significant relationships between land use patterns and water quality were found in this study, which demonstrated that further investigation is needed to identify the sources of water pollutants at a smaller scale.


Subject(s)
Rivers , Water Pollutants, Chemical , Alberta , Environmental Monitoring , Nitrogen/analysis , Spatio-Temporal Analysis , Water Pollutants, Chemical/analysis , Water Quality
19.
Environ Sci Technol ; 55(13): 8839-8847, 2021 07 06.
Article in English | MEDLINE | ID: mdl-34138548

ABSTRACT

Scale formation is a significant problem in a wide range of industries, including water treatment, food processing, power plants, and oilfield production. While surface modification provides a promising methodology to address this challenge, it has generally been believed that surface coatings with the lowest surface energy, such as fluorocarbon coatings, are most suitable for antiscaling applications. In contrast to this general knowledge, here we show that a liquid-like coating featuring highly mobile linear poly(dimethylsiloxane) (LPDMS) brush chains can bring an even better antiscaling performance than conventional perfluoroalkylsilane coatings, despite the fact that the former has much higher surface energy than the latter. We demonstrate that the LPDMS brush coating can more effectively inhibit heterogeneous nucleation of scale on a substrate compared with common perfluoroalkylsilane or alkylsilane coatings, and the dynamic liquid-like characteristic of the LPDMS brush coating is speculated to be responsible for its excellent nucleation inhibiting ability by reducing the affinity and effective interface interaction between the substrate and the scale nucleus. Our findings reveal the great prospect of using liquid-like coating to replace environmentally hazardous fluorine-containing organic ones as a green and cost-effective solution to address the scale problem with enhanced antiscaling performance.


Subject(s)
Fluorocarbons , Water Purification , Dimethylpolysiloxanes
20.
J Phys Chem Lett ; 12(14): 3577-3585, 2021 Apr 15.
Article in English | MEDLINE | ID: mdl-33819039

ABSTRACT

Super-liquid-repellent (SLR) surfaces based on surface micro/nanotextures are generally regarded as "non-wettable", though careful examination shows that residual microdroplets remain atop surface textures upon drop shedding-off. Despite its great importance, the origin of microscopic liquid residues remains poorly explored, and how to suppress residue formation is an open question. Herein, on the basis of high-speed microscopic imaging and numerical simulations, we resolve the fast formation dynamics of liquid residues on micropillared SLR surfaces and show that the competition of contact line receding on micropillars and the pinch-off of microcapillary bridges governs residue formation. The local receding angle can temporarily reduce to be drastically lower than the intrinsic one accompanying occurrence of accelerated contact line receding, inevitably leading to capillary bridge pinch-off and residue formation. We further show a liquid-like coating can delay capillary bridge pinch-off and reduce residue volume on SLR surfaces by more than 80% compared to those with conventional perfluoroalkylsilane coatings.

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