Droplet Surface Tension Research Articles

Microfluidic Formation of Honeycomb-Patterned Droplets Bounded by Interface Bilayers via Bimodal Molecular Adsorption.

Assembled water-in-oil droplets bounded by lipid bilayers are used in synthetic biology as minimal models of cell tissue. Microfluidic devices successfully generate monodispersed droplets and assemble them via droplet interface bilayesr (DIB) formation. However, a honeycomb pattern of DIB-bounded droplets, similar to epithelial tissues, remains unrealized because the rapid DIB formation between the droplets hinders their ability to form the honeycomb pattern. In this paper, we demonstrate the microfluidic formation of a honeycomb pattern of DIB-bounded droplets using two surfactants with different adsorption rates on the droplet surface. A non-DIB forming surfactant (sorbitan monooleate, Span 80) was mixed with a lipid (1,2-dioleoyl-sn-glycero-3-phosphocholine, PC), whose adsorption rate on the droplet surface and saturated interfacial tension were lower than those of Span 80. By changing the surfactant composition, we established the conditions under which the droplets initially form a honeycomb pattern and subsequently adhere to each other via DIB formation to minimize the interfacial energy. In addition, the reconstituted membrane protein nanopores at the DIBs were able to transport molecules. This new method, using the difference in the adsorption rates of two surfactants, allows the formation of a honeycomb pattern of DIB-bounded droplets in a single step, and thus facilitates research using DIB-bounded droplet assemblies.

Influence of Naturally Occurring Organic Surfactants on the Surface Tension of Sessile Droplets and Atmospheric Aerosols Measured with a Quasi-Elastic Laser Scattering System

Introduction Clouds are composed of atmospheric aerosols, micrometer sized aqueous droplets that are suspended in the air. These atmospheric aerosols play a key role in weather patterns and planet warming/cooling, making the understanding of their formation and propagation mechanisms highly important.[1] Despite the critical role aerosols play, there is still a fundamental lack in understanding of the processes that drive their formation and growth because there is no direct way to measure the surface tension of aerosol droplets in the atmosphere. In Köhler theory, which governs the formation and growth of aerosols, aerosol formation activity is driven by size and surface tension of the droplet, making an accurate measurement of aerosol surface tension integral to fully understanding cloud formation and evolution properties. In this study we utilize a new laser-based technique to measure the surface tension of micrometer sized droplets through droplet-surface capillary resonance and their response to naturally occurring pinene and limonene molecules exposed to the droplet surface. QELS Approach Thermal fluctuation drives the formation of capillary waves at a liquid interface, which can be observed with the quasi-elastic light scattering (QELS) technique (Figure 1). In our previous reports, the spontaneous resonance of thermally-induced capillary waves has been demonstrated on liquid surfaces with spatial confinement by a microchannel[2] and by a circular aperture.[3] Characteristic peaks corresponding to the capillary resonance appear in the QELS power spectrum. From the peak frequencies and spatial restriction conditions, surface tension can then be calculated.[4] Experimental Method In this work, micrometer sized aqueous droplets were generated by an ink-jet printer system and were immobilized in the path of a focused laser. Humid air was flown over the droplet to maintain size and shape, and QELS spectra collection/surface tension monitoring was started. Next, pinene or limonene were introduced to the air stream, interacting directly with the confined droplets. Surface tension properties were immediately affected by the presence of the hydrophobic molecules, causing the QELS spectra shape to change. The QELS spectra were monitored until equilibrium was reached. Finally, the trend in the surface tension of the droplets was calculated for each sample at various points during exposure to the surfactant molecules. Results and Conclusions In this study, we used the QELS method to probe the surface properties of micrometer sized droplets under a controlled atmosphere containing naturally occurring surfactant molecules. The results show that the presence of these hydrophobic molecules causes a clear suppression of the surface tension, which greatly impacts the aerosol droplet formation and growth properties, in turn impacting cloud formation and other related phenomena. The understanding of the influence of these molecules on the surface tension of aerosol droplets is expected to lead to enhanced knowledge on aerosol droplet formation mechanisms, which play a key role in cloud formation and weather phenomena.

Size Dependence of the Surface Tension of a Small Droplet under the Assumption of a Constant Tolman Length: Critical Analysis

Convincing arguments have been presented testifying that that the surface tension of a small spherical droplet must decrease upon diminishing droplet radius in correspondence with a positive constant Tolman length. The solution of the Gibbs–Tolman–Koenig–Buff equation has been found in the most compact form. The surface tension of a small spherical droplet has been calculated within the framework of the continual approximation using the Mie–Lennard-Jones interatomic pair potential.

Effect of Adjuvants and pH Adjuster on the Efficacy of Sulcotrione Herbicide

The effectiveness of herbicides is affected by the pH of the spray liquid. The use of adjuvants can mitigate the negative effect of pH, and it also allows for a reduction in herbicide doses while maintaining high efficiency. Greenhouse studies were performed to evaluate the efficacy of the herbicide sulcotrione (HRAC F2), against barnyardgrass, at full or reduced doses with adjuvants, and a modified pH of the solutions. The contact angle and surface tension of liquid spray drops, as well as the shear viscosity of individual solutions, were also tested. Results indicated that at a low pH of the spray liquid (4), the use of a reduced dose of sulcotrione with adjuvant based on methylated rapeseed oil can increase the effectiveness of barnyardgrass control to the same level as at the full dose of herbicide. The use of adjuvants contributed to the reduction in the contact angle and the surface tension of liquid spray droplets. No significant differences in shear viscosity were observed for individual solutions.

The surface tension of surfactant-containing, finite volume droplets

Surface tension influences the fraction of atmospheric particles that become cloud droplets. Although surfactants are an important component of aerosol mass, the surface tension of activating aerosol particles is still unresolved, with most climate models assuming activating particles have a surface tension equal to that of water. By studying picoliter droplet coalescence, we demonstrate that surfactants can significantly reduce the surface tension of finite-sized droplets below the value for water, consistent with recent field measurements. Significantly, this surface tension reduction is droplet size-dependent and does not correspond exactly to the macroscopic solution value. A fully independent monolayer partitioning model confirms the observed finite-size-dependent surface tension arises from the high surface-to-volume ratio in finite-sized droplets and enables predictions of aerosol hygroscopic growth. This model, constrained by the laboratory measurements, is consistent with a reduction in critical supersaturation for activation, potentially substantially increasing cloud droplet number concentration and modifying radiative cooling relative to current estimates assuming a water surface tension. The results highlight the need for improved constraints on the identities, properties, and concentrations of atmospheric aerosol surfactants in multiple environments and are broadly applicable to any discipline where finite volume effects are operative, such as studies of the competition between reaction rates within the bulk and at the surface of confined volumes and explorations of the influence of surfactants on dried particle morphology from spray driers.

Surface jets and internal mixing during the coalescence of impacting and sessile droplets

The internal dynamics during the coalescence of a sessile droplet and a subsequently deposited impacting droplet, with either identical or distinct surface tension, is studied experimentally in the regime where surface tension is dominant. Two color high-speed cameras are used to capture the rapid internal flows and associated mixing from both side and bottom views simultaneously by adding an inert dye to the impacting droplet. Given sufficient lateral separation between droplets of identical surface tension, a robust surface jet is identified on top of the coalesced droplet. Image processing shows this jet is the result of a surface flow caused by the impact inertia and an immobile contact line. By introducing surface tension differences between the coalescing droplets, the surface jet can be either enhanced or suppressed via a Marangoni flow. The influence of the initial droplet configuration and relative surface tension on the long-term dynamics and mixing efficiency, plus the implications for emerging applications such as reactive inkjet printing, are also considered.

INFLUENCE OF GLYPHOSATE CONCENTRATIONS ON SPRAY SOLUTION PHYSICOCHEMICAL CHARACTERISTICS AND DRIFT POTENTIAL

ABSTRACT The herbicide glyphosate is sprayed with varying application volumes that result in different concentrations used in the spray solutions. Thus, this study aimed to evaluate the effect of glyphosate concentrations on the potential risk of droplet drift, surface tension of spray solution, and contact angle of droplets on surfaces. Three experiments were conducted in a completely randomized design. Drift potential was evaluated by median volumetric diameter (MVD), percentage volume of droplets with diameter smaller than 100 μm (%V<100 μm), and coefficient of uniformity (Span), with 12 replications. The surface tension of spray solutions and contact angle of droplets were evaluated on Urochloa ruziziensis leaves, paraffin film, and glass, with four replications. Changing glyphosate concentrations in the spray solution changes the droplet spectrum and contact angle on different surfaces due to changes in spray solution physicochemical characteristics, such as surface tension. The increased glyphosate concentrations in the spray solution lead to increased drift potential of droplets, reducing the surface tension and contact angle of droplets on surfaces.

Pulsed Nano-Electrospray Ionization with a High Voltage (4000 V) Pulse Applied to Solutions in the Range of 200 ns to 1 ms.

To initiate electrospray, it is necessary to accumulate excess charges on the liquid surface until the outward electrostatic pressure (PE) overwhelms the inward pressure Pγ originating from the surface tension of the liquid droplet. In this report, electrospray mass spectrometry for solutions of gramicidin S (G), ubiquitin (U), and cytochrome c (C) in H2O/CH3OH (1/1) was performed as a function of the high voltage (4000 V) pulse width in the range of 200 ns to 1 ms using a 4 μm i.d. glass capillary. Multiply protonated ions for all three samples started to be detected with the 300 μs pulse width. Denaturation of C and U proceeded with an increase of the pulse width. When the bias voltage of ∼880 V that was lower than the threshold voltage for the generation of continuous electrospray (∼1000 V) was applied to the solution, multiply protonated G, U, and C were detected with the 200 ns pulse width. After the depletion of excess charges in 200 ns, it took 10-100 μs to regenerate electrospray.

A Numerical Investigation on the Collision Behavior of Polymer Droplets.

Binary droplet collisions are a key mechanism in powder coatings production, as well as in spray combustion, ink-jet printing, and other spray processes. The collision behavior of the droplets using Newtonian and polymer liquids is studied numerically by the coupled level-set and volume of fluid (CLSVOF) method and adaptive mesh refinement (AMR). The deformation process, the internal flow fields, and the energy evolution of the droplets are discussed in detail. For binary polymer droplet collisions, compared with the Newtonian liquid, the maximum deformation is promoted. Due to the increased viscous dissipation, the colliding droplets coalesce more slowly. The stagnant flow region in the velocity field increases and the flow re-direction phenomenon is suppressed, so the polymer droplets coalesce permanently. As the surface tension of the polymer droplets decreases, the kinetic and the dissipated energy increases. The maximum deformation is promoted, and the coalescence speed of the droplets slows down. During the collision process, the dominant pressure inside the polymer droplets varies from positive pressure to negative pressure and then to positive pressure. At low surface tension, due to the non-synchronization in the movement of the interface front, the pressure is not smooth and distributes asymmetrically near the center of the droplets.

Dependence of Surface Tension of a Droplet Formed on the Molecular Condensation Nucleus or Ion on the Droplet Radius

Abstract—The dependence of the thermodynamic surface tension of a small droplet formed on a molecular-size condensation nucleus on the droplet size, nucleus size, molecular field parameters, and nuclear charge in the case of an ion is investigated. Calculations have been performed for molecules of supersaturated argon vapor at different values of the chemical potential of the molecules in the framework of the gradient density functional theory (DFT) and the Carnahan–Starling model to take into account the contribution of hard spheres. The interaction of argon molecules with an uncharged condensation nucleus has been described by the Lennard–Jones potential. In the case of an ion, the long-range Coulomb potential of electric forces is additionally taken into account. The dielectric constant is defined as a function of the local density of the number of argon molecules. As a variable describing the size of the droplet, the radius of the equimolecular surface of the droplet is chosen. The obtained dependences of the surface tension of the droplets have been compared with the dependence of the surface tension on the size of droplet without a condensation nucleus. When the effect of the solvation layer is discarded, the dependence of the surface tension on the radius of the equimolecular surface of a small droplet with a condensation nucleus exhibits similar behavior as in the absence of the nucleus with almost the same negative Tolman correction. The effect of the rigidity constant, however, is clearly influenced by the existence of a condensation nucleus. It is shown that when the first solvation layer is divided around the condensation nucleus, the dependence of surface tension on the radius of the equimolecular surface of a small droplet with a condensation nucleus exhibits similar behavior with almost the same negative Tolman correction as in the absence of a nucleus, but with a different correction, namely, with effective rigidity constant for the surface layer.

Effects of surface tension time-evolution for CCN activation of a complex organic surfactant.

The physical processes and time scales underlying the evolution of surface tension in atmospheric solution droplets are largely unaccounted for in present models describing cloud droplet formation. Adsorption of surface-active molecules at the surface of a solution droplet depresses the droplet surface tension but also depletes solute from the droplet bulk, which have opposing and sometimes canceling effects in cloud droplet formation. In this work, we study the effect of time-evolving surface tension for cloud droplet activation of particles composed of Nordic Aquatic Fulvic Acid (NAFA) mixed with sodium chloride (NaCl). We model the formation of cloud droplets using Köhler theory with surface tension depression and bulk/surface partitioning evaluated from two different thermodynamic surface models. Continuous ternary parameterizations were constructed from surface tension measurements of macroscopic droplets at different time steps after the formation of a droplet surface. The predicted results are compared to previous measurements of mixed NAFA-NaCl cloud condensation nuclei (CCN) activity and a bulk solution model that does not take the NAFA bulk/surface partitioning equilibrium into account. Whereas the bulk model shows a trend in cloud droplet formation following that of macroscopic surface tension depression with time, the variation with time essentially disappears when bulk/surface partitioning is taken explicitly into account during droplet activation. For all equilibrium time steps considered, the effect of surface tension depression in the NAFA-NaCl system is counteracted by the depletion of solute from the finite-sized droplet bulk phase. Our study highlights that a comprehensive data set is necessary to obtain continuous parameterizations of surface tension and other solution properties required to fully account for the bulk/surface partitioning in growing droplets. To our knowledge, no similar data set currently exists for other aqueous organic systems of atmospheric interest. Additional work is necessary to deconvolve the effects of bulk/surface partitioning in the context of time-evolution on cloud droplet activation and to determine whether the results presented here can be further generalized.

Imbibition of Femtoliter-Scale DNA-Rich Aqueous Droplets into Porous Nylon Substrates by Molecular Printing.

This work presents the first reported imbibition mechanism of femtoliter (fL)-scale droplets produced by microchannel cantilever spotting (μCS) of DNA molecular inks into porous substrates (hydrophilic nylon). Differently from macroscopic or picoliter droplets, the downscaling to the fL-size leads to an imbibition process controlled by the subtle interplay of evaporation, spreading, viscosity, and capillarity, with gravitational forces being quasi-negligible. In particular, the minimization of droplet evaporation, surface tension, and viscosity allows for a reproducible droplet imbibition process. The dwell time on the nylon surface permits further tuning of the droplet lateral size, in accord with liquid ink diffusion mechanisms. The functionality of the printed DNA molecules is demonstrated at different imbibed oligonucleotide concentrations by hybridization with a fluorolabeled complementary sequence, resulting in a homogeneous coverage of DNA within the imbibed droplet. This study represents a first step toward the μCS-enabled fabrication of DNA-based biosensors and microarrays into porous substrates.

Flow characteristics of the molten pool in pulsed laser welding of thin sheet with filler wire

A 3D transient model has been developed to analysis the molten pool flow characteristic in pulsed laser welding thin sheet with filler wire. The free surface is tracked by VOF method, and the filler metal is simplified as droplets. The flow characteristics in welding of Hastelloy C-276 sheets with 0.5 mm in thickness are analyzed with this model. The calculated weld appearance fits well with the experimental one. Before the droplet contacts with the molten pool, the liquid metal driven by surface tension flows towards the center and downward at the upper surface. The max velocity at the center is about 0.97 m/s. At the trailing portion of lower surface, two eddies with similar spin direction are generated due to the outward surface flow and the downward flow. The filler metal has significant influence on the convection pattern in the molten pool, and results in the disappearance of flow characteristics dominated by surface tension. The filler metal flows downward and outward rapidly after the droplet contact with molten pool. The maximum velocity is about 1.74 m/s and appears at the location where the droplet enters into the molten pool. The droplet has an impact effect on the molten pool and the convection pattern is changed. The molten pool shows oscillation characteristic due to the combined effect of droplet impact and surface tension. The volume of the molten pool dose not decrease right after the laser pulse ends, the lower part of the molten pool expands for about 3–4 milliseconds. And this phenomenon is related to the pulse effect of the laser beam, the flow pattern of the molten pool and the thermal properties of the material. Due to high pulse frequency of the laser beam and low thermal conductivity of the material, the molten pool always exists during welding process.

Fabrication of β-carotene loaded glucuronoxylan-based nanostructures through electrohydrodynamic processing

Various concentrations of β-carotene (2.5–20% w/w dry mucilage weight) were loaded within Cydonia oblonga mucilage (COM) which further processed through electrohydrodynamic processing (EHP) to attain BC-Loaded nanostructures of high thermochemical stability. The BC loaded COM systems were characterized in terms of droplet size, rheological properties, surface tension, and electrical conductivity and their subsequent impacts on the morphology and physicochemical attributes of the produced nanostructures were studied. Increasing the β-carotene content, increased the viscosity and droplet size of colloidal systems but diminished their conductivity and surface tension. A transition from monomodal to bimodal size distribution was also observed at higher levels of β-carotene incorporation. In the case of EHP-produced nanostructures, scanning electron microscopy observations revealed a transition from nanoparticle to nanofiber by increasing the BC content from 2.5 to 20%. At lower concentrations of BC (2.5 and 5%) electrospraying was the dominant phenomenon that resulted in producing homogenous nanoparticles while the beaded fibers and nanofiber structures were obtained at 10 and 20% concentrations of BC, respectively. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and encapsulation efficiency of the produced nanostructures revealed successful encapsulation of BC into the COM polymer structure through EHP. The results of these assessments showed that the nano-particles comprising BC had more homogenous structure and higher encapsulated BC compared to the BC-loaded nano-fibers. The results of X-ray diffraction (XRD) and differential scanning calorimetry (DSC) measurements revealed amorphous structure of the produced nanostructures. Thermogravimetric assessments corroborated the higher thermal stability of BC loaded nanostructures compared with the free BC. These results provided novel information on the ability of COM in encapsulating bioactive agents through electrohydrodynamic processing.

Arsenic Speciation on Silver Nanofilms by Surface-Enhanced Raman Spectroscopy.

Surface-enhanced Raman spectroscopy (SERS), as a nondestructive and fast detection technique, is a promising alternative approach for arsenic detection, particularly for in situ applications. SERS-based speciation analysis according to the fingerprint SERS signals of different arsenicals has the potential to provide a superior technique in species preservation over the conventional chromatographic separation methods, albeit with some difficulties due to the similarity in SERS patterns. In this study, we explored a novel SERS method for arsenic speciation by using the separation potential of the coffee ring effect on negatively charged silver nanofilms (AgNFs). Four arsenic species, including arsenite (AsIII), arsenate (AsV), monomethylarsonic acid (MMAV), and dimethylarsinic acid (DMAV), were measured for fingerprint SERS signals in solution and on the films. Significant enhancement of SERS signals on the dried coffee ring stains by the AgNFs were observed except for AsIII, and more importantly, arsenicals migrated varying distances during coffee ring development, promoting better speciation. Sodium dodecyl sulfate was then introduced into the droplet to reduce the droplet surface tension, facilitating the migration of solution into the peripheral region. Under the combined interactions of arsenicals with the AgNFs, solvent, and surfactant, enhanced separation between arsenicals was observed as a result of the formation of two concentric rings. Combining the SERS fingerprint signals and physical separation of arsenicals on the surface, arsenic speciation was achieved using the AgNFs substrate-based SERS technology, demonstrating the potential of the coffee ring effect for rapid separation and analysis of small molecules by SERS.

Dynamic behavior of non-evaporative droplet impact on a solid surface: Comparative study of R113, water, ethanol and acetone

Droplet impact on a solid surface is a common phenomenon observed in industries. Fundamental investigations of droplet impact are helpful in enhancing spray cooling capability and advance spray–wall impingement model. In this work, the effects of droplet diameter, impact velocity, viscosity, and surface tension on droplet impact dynamics were systematically investigated with four liquids, that is, R113, deionized water, ethanol, and acetone. Results illustrated that the initial droplet diameter minimally affects morphology and dynamic spreading factor, whereas large viscosity and surface tension hindered droplet spreading, thereby yielding a small maximum spreading factor and velocity. Low droplet viscosity and surface tension contribute to enhancing spray cooling capability by producing improved atomization, large spreading velocity, and extended contact area. The existing maximum spreading factor correlations failed to predict experimental results accurately. On the basis of experimental data in this work, general maximum spreading factor and splashing threshold correlations are proposed. All the proposed correlations agreed well with the present experimental results and literature data. The maximum spreading factor correlation indicated that large droplet impact velocity, small viscosity, and surface tension will produce a large maximum spreading capability.

Elasto-capillary adhesion: Effect of deformability on adhesion strength and detachment

We study the interaction between capillary forces and deformation in the context of a deformable capillary adhesive: a clamped, tense membrane is adhered to a rigid substrate by the surface tension of a liquid droplet. We find that the equilibrium adhesive force for this elastocapillary adhesive is significantly enhanced in comparison to the capillary adhesion between rigid plates. In particular, the equilibrium adhesion force is orders of magnitude greater when the membrane is sufficiently deformed to contact the substrate. From a dynamic perspective, however, the formation of a fluid-filled dimple slows this approach to contact and means that stable attachment is only achieved if adhesion is maintained for a minimum time. The inclusion of a variable membrane tension (as a means of modifying the deformability) gives additional control over the system, allowing new detachment strategies to be explored.

Surface Tensions of Picoliter Droplets with Sub-Millisecond Surface Age.

Aerosols are key components of the atmosphere and play important roles in many industrial processes. Because aerosol particles have high surface-to-volume ratios, their surface properties are especially important. However, direct measurement of the surface properties of aerosol particles is challenging. In this work, we describe an approach to measure the surface tension of picoliter volume droplets with surface age <1 ms by resolving their dynamic oscillations in shape immediately after ejection from a microdroplet dispenser. Droplet shape oscillations are monitored by highly time-resolved (500 ns) stroboscopic imaging, and droplet surface tension is accurately retrieved across a wide range of droplet sizes (10-25 μm radius) and surface ages (down to ∼100 μs). The approach is validated for droplets containing sodium chloride, glutaric acid, and water, which all show no variation in surface tension with surface age. Experimental results from the microdroplet dispenser approach are compared to complementary surface tension measurements of 5-10 μm radius droplets with aged surfaces using a holographic optical tweezers approach and predictions of surface tension using a statistical thermodynamic model. These approaches combined will allow investigation of droplet surface tension across a wide range of droplet sizes, compositions, and surface ages.

Technical note: The role of evolving surface tension in the formation of cloud droplets

Abstract. The role of surface tension (σ) in cloud droplet activation has long been ambiguous. Recent studies have reported observations attributed to the effects of an evolving surface tension in the activation process. However, the adoption of a surface-mediated activation mechanism has been slow and many studies continue to neglect the composition dependence of aerosol–droplet surface tension, using instead a value equal to the surface tension of pure water (σw). In this technical note, we clearly describe the fundamental role of surface tension in the activation of multicomponent aerosol particles into cloud droplets. It is demonstrated that the effects of surface tension in the activation process depend primarily on the evolution of surface tension with droplet size, typically varying in the range 0.5σw≲σ≤σw due to the partitioning of organic species with a high surface affinity. We go on to report some recent laboratory observations that exhibit behavior that may be associated with surface tension effects and propose a measurement coordinate that will allow surface tension effects to be better identified using standard atmospheric measurement techniques. Unfortunately, interpreting observations using theory based on surface film and liquid–liquid phase separation models remains a challenge. Our findings highlight the need for experimental measurements that better reveal the role of composition-dependent surface tensions, critical for advancing predictive theories and parameterizations of cloud droplet activation.

PENGARUH TEGANGAN PERMUKAAN TERHADAP TUMBUKAN MULTIPLE DROPLETS PADA PERMUKAAN STAINLES STEEL YANG DIPANASKAN

The present study was conducted to investigate the dynamics of multiple droplets impact under various surface tensions. Here, the ethylene glycol with compositions of 0%, 5%, and 15% were injected through a nozzle into the stainless steel surface as the multiple droplets. The solid surface was heated at the temperatures of 150ºC. The dynamic of multiple droplets have been observed with frame rate of 2000 fps by a high speed camera. A technique of image processing was developed to determine the maximum droplets are spreading ratio. As the result, the surface tension contribute to the maximum spreading ratio significantly. When the droplet surface tension decreases, the maximum spreading ratio increases. The maximum spreading ratio appears when the percentage of the ethylene glycol is 15% at the temperature of 150ºC. From the visual observation, it was shown that a slower emergence of secondary droplets (droplet splashing) was carried out under low surface tension.