Hydrophilic Glass Research Articles

Cyclone-coalescence separation technology for enhanced droplet removal in natural gas purification process

Natural gas is increasingly recognized as a clean energy source due to its high quality, low pollution levels, and abundant availability. However, certain gas fields contain complex components that require purification for efficient transportation and utilization. Addressing these issues involves efficient gas–liquid separation technology. Existing gas–liquid separation units face challenges such as efficiency, liquid entrainment, energy consumption, and the need for consumable replacement. This study focuses on a novel cyclone-coalescence separator that combines centrifugal and coalescence principles. Implemented in a high-acid natural gas purification plant in China, the cyclone-coalescence separator demonstrated efficiency primarily influenced by gas velocity and diameter. Optimal performance was observed with a 75 mm diameter reactor at velocities of 8–12 m s−1, achieving a peak efficiency of 96%. The hydrophilic glass fiber with a monofilament structure can coalesce droplets effectively. In practical industrial use, under operational conditions, the hydrocyclone's liquid discharge rate is 89.6 kg·h−1 with an inlet concentration of 382.7 g·m3. Over a 400-h cycle, the cyclone-coalescence separator demonstrated superior separation performance with an average liquid discharge volume of 9.09 mg·kg−1, compared to 4.93 mg·kg−1 for the precision filter. This successful industrial implementation presents a promising approach to natural gas purification.

PhagoScreener: A novel phagogram platform based on a capillary-wave microbioreactor

Due to the overuse of antibiotics, the number of multidrug-resistant pathogen bacteria is rising in recent years posing a serious threat to human health. One promising alternative for treatment is the application of phage therapy using highly selective bacteriophages. Because of their selectivity, individual screens called phagograms for each patient are required to select phages from a phage library. Phagograms are mostly performed via bacterial cultivation on double layer agar plates and phage addition causing bacterial lysis. However, these assays are work-intensive and have a low ability for parallelization and automation. Hence, highly parallelizable and automatable microbioreactors in the lowest microliter scale could offer an economic solution increasing the throughput of phagograms. This paper demonstrates the applicability of a novel capillary-wave microbioreactor (cwMBR) to perform phagograms. Due to its small volume of only 7 µL and the open-droplet design, it can be easily automated and parallelized in future. Furthermore, the ability of online biomass measurement makes the cwMBR a perfect phagogram platform in the future. Herein, phagograms with E. coli and different concentrations of the phages MM02 and EASG3 were performed as proof of concept for phagograms in the cwMBR. Thereby, the cwMBR was able to measure differences in lysis kinetics of different phages. Furthermore, the phagograms were compared to those in conventional microtiter plate readers revealing the cwMBR as ideal alternative for phagograms as it combines favorable mixing conditions and a phage repellent hydrophilic glass surface with online biomass measurement in an open-droplet design for future parallelization and automation.

Droplet–droplet vapor-mediated interactions in confined environments

The evaporation of multiple droplets ensues ubiquitously in nature and industry. Vapor mediation caused by evaporating neighboring droplets is a demonstrated phenomenon that shows that droplets can interact with each other via the vapor in both open and confined configurations, i.e., the “shielding effect.” However, interactions between paired droplets in confined environments, more common in industrial processes, remain unexplored. In this Letter, we experimentally investigate the evaporation of water based paired sessile droplets on hydrophilic glass slides at different spacings in the absence and presence of an enclosed chamber. The results demonstrate that a confined environment significantly attenuates droplet evaporation, which intensifies with decreasing spacing between droplets. A 30%–82% increase in the droplet lifetime is found for the shortest distance studied in a confined environment, while results in an open environment are provided as a control. Both the local shielding effect and the global vapor accumulation due to confinement collaboratively induce such strong evaporation suppression. In addition, two well differentiated evaporation regimes ensue in a confined environment where the shielding effect initially dominates the evaporation suppression, whereas confinement governs the later evaporation stage. The later stage accounts for over 60% of the droplet lifetime. Such transition and further evaporation suppression, when compared to the classical shielding effect, highlights the importance of a confined environment in multiple droplet evaporation.

Versatile Underwater Pressure Sensitive Adhesive: UV Curing Synthesis and Substrate-Independent Adhesion.

The demand for underwater pressure sensitive adhesives (PSAs) is rapidly increasing in fields such as underwater engineering and biomedicine. However, the achievement of underwater adhesion of PSAs remains a challenge because of the hydration layer that hinders the interaction between the adhesive and the substrate. Herein, a new type of underwater PSA was synthesized by the copolymerization of hydrophobic unsaturated poly(1,2-butylene oxide) (UPBO) and hydrophilic itaconic acid monomers using solvent-free ultraviolet curing. The PSA has demonstrated substrate-independent underwater adhesion strengths ranging from 108 to 141 kPa on both hydrophilic (glass, wood, steel) and hydrophobic (PET, PMMA, PTFE) substrates. The underwater adhesion performance of PSA remains stable during 30 adhesion-detachment cycles and incubation in water for 20 days. Notably, PSA shows cytocompatibility, antimicrobial, and degradable properties and can be used for rapid hemostasis of skin wounds. Experimental characterizations confirm that the process of underwater adhesion is achieved by hydrophobic alkyl side chains of the PBO chain segments, which repel water at the adhesive-substrate interface. This study should provide both practical and facile design strategies for multifunctional underwater PSAs that can be used in a variety of applications.

Unlocking the potential of supramolecular polymers with bimodal molecular weights for instant and strong underwater adhesion

Developing adhesives suitable for underwater environments remains a formidable challenge due to the barrier presented by water, hindering contact between the adhesive and adherend. In this work, supramolecular adhesives prepared by mixing low and high molecular weight poly(butyl acrylate)-based copolymers are manifested to function effectively for underwater adhesion regardless of substrates’ affinity to water. Optimization of adhesion performance is achieved by manipulating the copolymer composition, resulting in the remarkable adhesion strengths of 1290 N m-1 and 1047 N m-1 to hydrophobic PET and hydrophilic glass substrates, respectively. The observed high underwater adhesion is attributed to a synergistic effect: instant and efficient removal of the hydration layer facilitated by the low molecular weight polymer strands, and mechanical resilience conferred by the high molecular weight strands featured by chain entanglements. Adequate interfacial interactions are attained by the supramolecular interactions including cation-π and π-π bonding. Notably, owing to its inherent hydrophobicity, the adhesive can be stored underwater for over a week and still displays 842 N m-1 peel strength to glass substrate. This work unlocks the potential of supramolecular adhesives with bimodal molecular weight distribution for instant and strong underwater adhesion, providing a straightforward yet scalable strategy to produce high-performance underwater adhesives.

Wettability of non‐metallic inclusions and its impact on bubble‐induced flotation kinetics

AbstractCeramic refractory bubbling devices may be applied in the steel ladle to induce the flotation of non‐metallic inclusions to the slag phase. These inclusions have many origins along the steelmaking process and induce a detrimental effect on the mechanical properties of these metals. Therefore, the design of high‐performance ceramic plugs relies on understanding the fundamentals of non‐metallic inclusions captured by the gas bubbles. This study investigated the flotation dynamics of hydrophobic and hydrophilic hollow glass particles through experimentation using a water model and quantifying the particle concentration via light scattering. Both types of particles exhibited a comparable natural flotation removal rate, whereas a 40% increase for hydrophobic particles was observed when introducing 1.1 mm bubbles (at 25 NL/h) enhancing the efficiency from 43.1% to 65.2%. For hydrophilic particles, the efficiency increased from 59.1% to 86.2% when bubbles were injected into the system, whereas the removal rate decreased by 2.1‐fold. The consequence of the practice of inert gas purging to remove non‐metallic inclusions is also discussed.

Effect of Particle-Substrate Interactions on Colloidal Layer Structure Prepared by Convective Self-Assembly Using Polyelectrolyte-Grafted Silica Particles.

Cationic and anionic polyelectrolytes, poly(vinylbenzyl trimethylammonium chloride) (PVBTA) and poly(sodium styrene sulfate) (PSSS), were grafted on the surface of the silica particles, respectively, and then these two types of polyelectrolyte-grafted silica particles were applied to the colloidal layer preparation by convective self-assembly (CSA) using hydrophilic or hydrophobic glass substrates to investigate the effect of the interactions between the particles and the substrate surface on the resultant layer structures. When the PVBTA-grafted silica particle (PVBTA-Si) was used, the colloidal monolayers with a non-close-packed (NCP) structure were formed on both hydrophilic and hydrophobic glass substrates, where the NCP colloidal layers on the hydrophobic glass substrate have a somewhat more ordered structure than those on the hydrophilic glass substrate. In the case of the PSSS-grafted silica particle (PSSS-Si), on the other hand, stripe patterns with close-packed (CP) colloidal layers were obtained on both types of the glass substrates. The number of layers of the stripes on the hydrophilic glass substrate was less than that on the hydrophobic glass substrate, while the spacing and width of the stripes on both substrates were similar to each other. The difference in the structures of the colloidal layers obtained here indicates that an attractive interaction, such as an electrostatic attraction and a hydrophobic interaction, between the particle and the substrate surface is necessary to achieve the NCP structure by the CSA process using polyelectrolyte-grafted silica particles.

Selective visual detection of multiplex PCR amplicon using magnetic microbeads

Nucleic acid amplification tests (NATs), such as genetic tests using polymerase chain reaction (PCR), are sensitive methods for detecting pathogens and food contamination. The rapid, easy, and inexpensive detection of amplicons, DNA, or RNA is key to realizing on-site NATs. We have previously developed a novel amplicon detection method using magnetic microbeads based on the hydrophobicity of DNA in deionized water. In this study, we aimed to expand the method for the detection of multiplex DNA amplicons. Tagged primers and probes for selective attachment were used to detect amplicons from two strawberry pathogens. The amplicon-labeled magnetic microbeads were placed in the round-bottom well of a hydrophilic glass substrate. The attachment of amplicons to the magnetic microbeads changed their surface from hydrophilic to hydrophobic. The magnetized microbeads concentrated at the bottom when the substrate was placed on a permanent magnet, and the concentrated microbeads were easily recognizable by the naked eye. Microbeads without amplicons were adsorbed over a broad area of the bottom of the glass well owing to their hydrophilicity. The appropriate tag probe was attached to specific amplicons for detection, and each amplicon from multiplex PCR was selectively detected within approximately 15 min. Notably, this method requires no electric power and contributes to the realization of on-site NAT detection. This study presents a simple and rapid method for the selective detection of multiplex PCR amplicons using DNA–DNA hybridization.

Effects of heterogenous wettability on evaporation from a simulated soil pore: Stick-slip evaporative mode and contact line motion

The Ogallala Aquifer, a primary irrigation water source in the High Plains region of the United States, is declining, thereby necessitating new water conservation strategies. This paper investigates the impact of mixed wettability on the evaporation dynamics of a 10-µl sessile water droplet placed within simulated soil pores comprised of hydrophobic Teflon beads (CA ∼ 108°) and hydrophilic glass (CA ∼ 41°) beads with 2.38-mm diameters, where homogeneous and heterogenous (i.e., mixed hydrophobicity and hydrophilicity) wettability configurations were investigated. Experiments were performed in an environmental chamber where the relative humidity and temperature were 60% ± 0.1% RH and 20 ± 0.4 °C, respectively. Wettability influenced evaporation times, with homogeneous hydrophobic pores (i.e., three Teflon beads) and heterogenous one glass, two Teflon pores having the longest average evaporation times of 40 and 39 min, respectively. Homogeneous hydrophilic pores (i.e., three glass beads) and heterogenous two glass, one Teflon pores exhibited evaporation times of 34 min. Evaporation times for heterogenous combinations trended based on the predominant wettability. Contact angles and the projected length of contact were analyzed from videos to capture pinning and depinning during evaporation. For many cases including hydrophobicity, contact angles were less than 90°, and in some configurations, water would be pinned on a Teflon bead, whereas depinning (i.e., moving) on a glass bead. Stick-slip evaporation was observed, where the evaporating droplet switched between constant contact radius and constant contact area evaporative modes to minimize droplet surface energy. The results suggest wettability alterations in agricultural settings may reduce evaporation.

Influence of hydrophobic particles on the film drainage during bubble–solid interaction

In this article, we investigate the complex drainage behavior of liquid (“dimple”) films entrapped between hydrophilic glass substrates and air bubbles in water and aqueous suspensions of polystyrene (PS) particles. The film drainage was monitored by capturing the evolution of spatial-temporal thicknesses using interferometry. Faster drainage of the entrapped film is observed in the PS colloid suspensions compared to the water. The film drainage strongly depends on the interface boundary conditions. Our experiments reveal that the air–liquid interface of the entrapped film becomes partially mobile in the PS suspensions, which results in faster drainage. The hydrophobic PS particles tend to migrate toward the air–water interface and form an ordered layer. We argue that the adsorbed layer of PS particles makes the bubble surface elastic, delaying the formation of the immobile interface.

Adhesion preference of the sticky bacterium Acinetobacter sp. Tol 5.

Gram-negative bacterium Acinetobacter sp. Tol 5 exhibits high adhesiveness to various surfaces of general materials, from hydrophobic plastics to hydrophilic glass and metals, via AtaA, an Acinetobacter trimeric autotransporter adhesin Although the adhesion of Tol 5 is nonspecific, Tol 5 cells may have prefer materials for adhesion. Here, we examined the adhesion of Tol 5 and other bacteria expressing different TAAs to various materials, including antiadhesive surfaces. The results highlighted the stickiness of Tol 5 through the action of AtaA, which enabled Tol 5 cells to adhere even to antiadhesive materials, including polytetrafluoroethylene with a low surface free energy, a hydrophilic polymer brush with steric hindrance, and mica with an ultrasmooth surface. Single-cell force spectroscopy as an atomic force microscopy technique revealed the strong cell adhesion force of Tol 5 to these antiadhesive materials. Nevertheless, Tol 5 cells showed a weak adhesion force toward a zwitterionic 2-methacryloyloxyethyl-phosphorylcholine (MPC) polymer-coated surface. Dynamic flow chamber experiments revealed that Tol 5 cells, once attached to the MPC polymer-coated surface, were exfoliated by weak shear stress. The underlying adhesive mechanism was presumed to involve exchangeable, weakly bound water molecules. Our results will contribute to the understanding and control of cell adhesion of Tol 5 for immobilized bioprocess applications and other TAA-expressing pathogenic bacteria of medical importance.

Preventing Static Biofilm Formation of Staphylococcus aureus on Different Types of Surfaces Using Microbubbles.

Bacterial fouling and biofilm formation on surfaces have been ongoing problems in real life as well as in the medical field. Different approaches have been taken to tackle the issues, from costly surface modification to antibiotic-delivering strategies. In this study, we examined the potential of using stabilized microbubbles (MBs) to shield against bacterial adhesion. Three types of surfaces were tested: hydrophilic glass (hydrophilic surface), neutral hydrophobic polystyrene (PS)-coated surfaces, and negatively charged hydrophobic octadecyltrichlorosilane (OTS)-coated surfaces. By evaluating the colony-forming unit (CFU) values from each surface, MBs stabilized by 0.05 mM SDS were shown to only produce significant reduction of Staphylococcus aureus adhesion on PS surfaces, up to 60.29 and 82.32% compared to no-MB PS surfaces, and no-MB uncoated surfaces, correspondingly, due to the appropriate size, stability, and negative charges of the MB shielding layer. On the other hand, OTS coatings had an intrinsic antiadhesion effect (69.83% compared to uncoated surface), given that the negatively charged OTS-aqueous interface or surface porosity nature of the coating prohibited the attachment of MBs, leading to the elimination of the antifouling effect of MBs. Ultimately, MBs gave better shielding results than surface modification when compared to uncoated surfaces and hence can be applied more widely.

Photo-controllable microcleaner: photo-induced crawling motion and particle transport of azobenzene crystals on a liquid-like surface.

Organic crystals of 3,3'-dimethylazobenzene (DMAB) exhibit photo-induced crawling motion on solid surfaces when they are simultaneously irradiated with ultraviolet and visible light from opposite directions. DMAB crystals are candidates for light-driven cargo transporters, having simple chemical compositions and material structures. However, fast crawling motion without significant shape deformation has not yet been achieved. In this study, compared with hydrophilic glass and conventional hydrophobic surfaces with alkyl chains, siloxane-based hybrid surfaces, which are "liquid-like surfaces," result in the fastest crawling motion (4.2 μm min-1) while the droplet-like shape of DMAB crystals is maintained. Additionally, we successfully demonstrate that the DMAB crystals are capable of capturing and carrying silica particles on the hybrid surface. The transport direction is changed on demand without releasing the particles by simply changing the irradiation direction. The particles can be left on the substrate by removing the DMAB crystals via sublimation at room temperature. This result showcases a new concept of "photo-controllable microcleaner" that can operate a series of cargo capture-carry-release tasks. We expect this transporter to contribute to the development of crystal actuators, microfluidics, and microscale molecular flasks/reactors.

Study of electro-migration and capture of particles by a charged pendant droplet

To understand the particle scavenging mechanisms by charged droplets in air cleaning technologies, we investigate the phenomena of non-incorporation/non-attachment and return/rebound of airborne particles/clusters upon impacting charged droplets. Using high-speed imaging, the motion and fate of particles and clusters lifted from a surface and colliding with a stationary droplet suspended from an electrified needle are examined in detail. Aggregates of glass beads and carbon particles are employed to explore how material characteristics, such as hydrophobicity/hydrophilicity, conductivity, and dielectric constant, influence their capture by the droplet. Analysis of observed cluster trajectories along with numerical modelling has been carried out to provide insights into their charges and velocities. DC and AC electric field experiments unequivocally demonstrate that the Faradaic induction mechanism at both the ground and droplet surfaces causes the acquisition or reversal of particle charges. The migration of particles and clusters is predominantly governed by Coulombic force, not dielectrophoretic force (DEP). Hydrophobic carbon particle clusters with high conductivity exhibit increased rebound/non-incorporation from the droplet, whereas hydrophilic glass beads with low conductivity do not show significant rebound and readily integrate into the droplet. The study demonstrates that (i) particles deposited on surfaces suffer resuspension and (ii) the capture of particles striking a charged droplet surface may not take place universally but could have a strong dependence on the chemical and material nature of the particles. Although the study is based on aggregated clusters and not on individual particles, it opens up avenues for future research using smaller particles and droplet systems relevant to air-cleaning applications.

General Strategies for Preparing Hybrid Polymer/Quantum Dot Nanocomposites for Color Conversion

Quantum dots (QDs), with their exceptional optical properties, have emerged as promising candidates to replace traditional phosphors in lighting and display technologies. This study delves into the integration strategies of QDs within glass and polymer matrices to engineer advanced quantum dot color converters (QDCCs) at the industrial scale for practical applications. To achieve enhancements in the photostability and thermal stability of QDCCs, we explore two distinct approaches: the dispersion of QDs in a hydrophilic glass matrix via a sol–gel process and the incorporation of QDs into a non-polar acrylate monomer to formulate QD/polymer nanocomposites. This research further investigates the optical behaviors of these composites, focusing on their light-scattering and propagation mechanisms, which are critical for optimizing light extraction efficiency in QDCCs. Additional optical film and light-scattering particles can improve color conversion efficiency by ~140%. These advancements present a significant step forward in the development of high-performance, energy-efficient, QD-based lighting and display systems.

Assessing the Influence of Polymer-Based Anti-Drift Adjuvants on the Photolysis, Volatilization, and Secondary Drift of Pesticides after Application

One practice to reduce spray drift during pesticide application is the addition of certain chemical adjuvants to spraying solutions, which change their physicochemical properties and result in larger droplets. The environmental impact of these agrochemicals continues however also after application, depending on surface processes occurring upon treated surfaces. While the impact of anti-drift adjuvants has been studied regarding spray drift, their impact on the fate of deposited pesticides has received little attention. Here, the effect of a polymer-based adjuvant (polyacrylamide) on the photolysis and evaporation rates of pyrimethanil (common fungicide) from dry films were investigated under controlled laboratory conditions and during two field studies. The laboratory results indicate that the adjuvant enhances the volatilization and photolysis rate both on hydrophobic lemon leaves and hydrophilic glass substrates. These results can be attributed to an increase in the geometrical area of residual film and a widening of its circumference rim, where solutes are likely to concentrate, when generated from adjuvant-containing droplets. Such morphological differences may enhance the exposure of deposited pesticides to interact with the overlaying atmosphere and incident radiation. The field data was less conclusive, suggesting a small impact of the anti-drift adjuvant on the fungicide’s secondary drift from crops and an even lower effect on volatilization from bare soil.

Multilayer, Broadband Infrared Reflectors Based on the Photoinduced Preparation of Cholesteric Liquid Crystal Polymers.

This paper focuses on preparing broadband reflective liquid crystal films through the diffusion of monofunctional and bifunctional monomers in a photoinduced trilayer system. By combining the hydrophilic and hydrophobic liquid crystal glass surface treatment technologies, the polymer network of polymer-stabilized cholesteric liquid crystal (PSCLC) itself serves as a diffusion channel to form a trilayer cholesteric liquid crystal composite system containing bifunctional monomers, a nematic liquid crystal composite system, and a cholesteric liquid crystal composite system containing monofunctional monomers. Utilizing the difference in the polymerization rates of monofunctional and difunctional polymerizable monomers, the monomers and chiral compounds diffuse relative to each other, so that the liquid crystal pitch exhibits a gradient distribution, and the broadened reflective width can reach up to 1570 nm. There is no doubt that new and improved processes and technologies offer important possibilities for preparing and applying PSCLC films.

FXII contact activation products have an inhibitory effect on αFXIIa.

It is accepted that the contact activation complex of the intrinsic pathway of blood coagulation cascade produces active enzymes that lead to plasma coagulation following biomaterial contact. In this study, FXII was activated through contact with hydrophilic glass beads and hydrophobic octadecyltrichlorosilane-modified glass beads from neat buffer solutions. These FXII contact activation products generated from material interaction were found to suppress the procoagulant activity of exogenous αFXIIa, and this inhibition was dependent on surface wettability and the concentration of exogenous αFXIIa. Higher relative inhibition rates were generally observed at low concentrations of αFXIIa (1-2 μg/mL) while both hydrophobic and hydrophilic materials showed similar inhibition levels (~39%) at high concentrations of αFXIIa (20 μg/mL). The presence of prekallikrein in the activation system increased the amount of FXIIa produced during FXII contact activation, and also suppressed the apparent levels of inhibitors on hydrophilic surfaces, while having no effect on apparent levels of inhibitors on hydrophobic surface. The combination of FXII contact activation products and activator surfaces was found to dramatically increase inhibition of αFXIIa activity compared to the activation products alone, regardless of activator surface wettability and the presence of prekallikrein. This finding of inhibitors in the suite of proteins generated by contact activation provides additional knowledge into the complex series of interactions that occur when plasma comes into contact with material surfaces.

Porous polydimethylsiloxane films with specific surface wettability but distinct regular physical structures fabricated by 3D printing.

Porous polydimethylsiloxane (PDMS) films with special surface wettability have potential applications in the biomedical, environmental, and structural mechanical fields. However, preparing porous PDMS films with a regular surface pattern using conventional methods, such as chemical foaming or physical pore formation, is challenging. In this study, porous PDMS films with a regular surface pattern are designed and prepared using 3D printing to ensure the formation of controllable and regular physical structures. First, the effect of the surface wettability of glass substrates with different surface energies (commercial hydrophilic glass and hydrophobic glass (F-glass) obtained by treating regular glass with 1H,1H,2H,2H-perfluorooctyl-trichlorosilane) on the structural characteristics of the 3D printed PDMS filaments is investigated systematically. Additionally, the effect of the printing speed and the surface wettability of the glass substrate on the PDMS filament morphology is investigated synchronously. Next, using the F-glass substrate and an optimized printing speed, the effects of the number of printed layers on both the morphologies of the individual PDMS filaments and porous PDMS films, and the surface wettability of the films are studied. This study reveals that regularly patterned porous PDMS films with distinct structural designs but the same controllable surface wettability, such as anisotropic surface wettability and superhydrophobicity, can be easily fabricated through 3D printing. This study provides a new method for fabricating porous PDMS films with a specific surface wettability, which can potentially expand the application of porous PDMS films.

Influence of step-down pressure on wettability-controlled heterogeneous bubble nucleation of sparingly soluble gases in water

The liberation of dissolved gas from a liquid typically occurs either by diffusion through the gas–liquid interface and/or by bubble nucleation at the solid–liquid interface. The goal of this research was to study the influences of step-down pressure (degree of supersaturation) and wettability on the onset pressure for bubble nucleation of sparingly soluble gases, methane and nitrogen, in water. Bubble nucleation experiments were carried out with the gas-supersaturated liquids in the hydrophilic (untreated) and hydrophobic (treated) glass vials. The gas-saturated liquids were prepared by saturating water with methane or nitrogen in a glass vial placed in a pressure cell at 6,000 mbar for a minimum of 16 or 15 h, respectively. To initiate the pressure-driven bubble nucleation process, 100-, 500-, or 6,000-mbar step-down pressures were applied to the pressure cell until the bubble nucleation was initiated. Bubble nucleation did not occur in the hydrophilic vial with any of the gas-supersaturated waters, irrespective of the step-down pressures. Unexpectedly, 100-mbar step-down pressure did not cause neither methane nor nitrogen bubble nucleation in the hydrophobic vials. Whereas, both methane and nitrogen bubble nucleations occurred in the hydrophobic vials when the step-down pressure was increased to 500 mbar. The above experimental findings revealed the importance of step-down pressure and surface wetting nature on sparingly soluble gas bubble nucleation. To further understand the experimental findings, an analytical method was developed to estimate the effective supersaturations using Fick’s 2nd law of diffusion and Henry’ law, which indicated that at any given pressure the 500-mbar step-down pressure creates higher supersaturation compared to 100-mbar step-down pressure.