Characterization of the topography and wettability of English weed leaves and biomimetic replicas

Pereira, Pedro M.; Moita, Ana S.; Monteiro, Gabriel A.; Prazeres, D.M.F.

doi:10.1016/s1672-6529(14)60048-2

Cited by 28 publications

(20 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Wettability can be described as a property governed by intermolecular interactions that characterizes the degree of wetting of a solid surface by a liquid droplet. One common way of characterizing wettability is through the measurement of the static CA θeq that results from the equilibrium between the interfacial tensions between solid, liquid, and vapor phases [11]. A surface is typically defined as water wetting for (approximately) θint<60° to 75° (measured through the aqueous phase), NAPL (non-aqueous phase liquid) wetting for θint>105° to 120°, and intermediate wetting for 75°<θint<105° [12].…”

Section: Introductionmentioning

confidence: 99%

Wettability and Other Surface Properties of Modified Polymers

Kasálková¹,

Slepička²,

Kolská³

et al. 2015

Wetting and Wettability

View full text Add to dashboard Cite

Surface wettability is one of the crucial characteristics for determining of a material's use in specific application. Determination of wettability is based on the measurement of the material surface contact angle. Contact angle is the main parameter that characterizes the drop shape on the solid surface and is also one of the directly measurable properties of the phase interface. In this chapter, the wettability and its related properties of pristine and modified polymer foils will be described. The wettability depends on surface roughness and chemical composition. Changes of these parameters can adjust the values of contact angle and, therefore, wettability. In the case of pristine polymer materials, their wettability is unsuitable for a wide range of applications (such as tissue engineering, printing, and coating). Polymer surfaces can easily be modified by, e.g., plasma discharge, whereas the bulk properties remain unchanged. This modification leads to oxidation of the treated layer and creation of new chemical groups that mainly contain oxygen. Immediately after plasma treatment, the values of the contact angles of the modified polymer significantly decrease.In the case of a specific polymer, the strongly hydrophilic surface is created and leads to total spreading of the water drop. Wettability is strongly dependent on time from modification.Wettability plays a key role, e.g., in the development of biomaterials in tissue engineering and regenerative medicine. Biocompatibility tests of the cell adhesion, proliferation and viability are performed in an aqueous medium, and it is necessary to control the surface wettability. Various cell types have different requirements on surface properties, but while maintaining suitable parameters, the optimal value of © 2015 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.water contact angle for cell adhesion is in the interval of 50-70°. In the case of polymers, which have usually higher values of contact angles, the decrease in water contact angle and adjustment of the surface may be accomplished by introducing selected chemical groups (by plasma treatment), chemical compounds (by grafting, i.e., chemical bath deposition), or nanoparticles. In the case of grafting of polyethylene glycol (PEG) on the plasma activated high-density polyethylene was under "properly" selected conditions of modification (molecular weight of PEG, concentration of PEG in solution) prepared layers that positively influenced the cell adhesion. In addition, low concentration of gold nanoparticles increased the number of adhered cells without decreasing cell viability.Whether the surface of the polymeric substrate is attractive for the adhesion and proliferation of cells is determined not only by wettability but also by a range of other surface properties...

show abstract

Section: Introductionmentioning

confidence: 99%

Wettability and Other Surface Properties of Modified Polymers

Kasálková¹,

Slepička²,

Kolská³

et al. 2015

Wetting and Wettability

View full text Add to dashboard Cite

show abstract

“…For example, David [20]. Moreover, the dynamic wetting such as transition energy barriers was studied through droplet interactions [21]. Even though the wetting properties on the irregularly micro-structured surface were theoretically simulated with regard to the relationship between surface fractal feather and heterogeneous nucleation [22], the simulated results were not further verified by corresponding experiments or actual applications.…”

Section: Introductionmentioning

confidence: 99%

Characterization of irregularly micro-structured surfaces related to their wetting properties

Xie

Deng

2015

Applied Surface Science

View full text Add to dashboard Cite

“…The surface is considered to be smooth, with a mean roughness amplitude of the order of 0m±0.02m, as evaluated by a Dektak 3 profile meter (Veeco). A detailed description of the experimental procedure taken to characterize the wettability of the surfaces can be found in [14]. An infrared IR-high speed camera (MWIR-InSb from Xenics 179 -ONCA 4696 series) and a high-speed camera (Phantom v4.2) are placed bellow the heated surface and on the side, respectively, to capture simultaneous (but not synchronized) thermal and dynamics images of the impacting droplet.…”

Section: Experimental Arrangement and Methodologymentioning

confidence: 99%

Experimental and numerical study on sensible heat transfer at droplet/wall interactions

Teodori

Pontes

Moita

et al. 2017

Proceedings ILASS–Europe 2017. 28th Conference on Liquid Atomization and Spray Systems

Self Cite

View full text Add to dashboard Cite

The present study addresses a detailed experimental and numerical investigation on the impact of water droplets on smooth heated surfaces. High-speed infrared thermography is combined with high-speed imaging to couple the heat transfer and fluid dynamic processes occurring at droplet impact. Droplet spreading (e.g. spreading ratio) and detailed surface temperature fields are then evaluated in time and compared with the numerically predicted results. The numerical reproduction of the phenomena was conducted using an enhanced version of a VOFbased solver of OpenFOAM previously developed, which was further modified to account for conjugate heat transfer between the solid and fluid domains, focusing only on the sensible heat removed during droplet spreading. An excellent agreement is observed between the temporal evolution of the experimentally measured and the numerically predicted spreading factors (differences between the experimental and numerical values were always lower than 3.4%). The numerical and experimental dimensionless surface temperature profiles along the droplet radius were also in good agreement, depicting a maximum difference of 0.19. Deeper analysis coupling fluid dynamics and heat transfer processes was also performed, evidencing a strong correlation between maximum and minimum temperature values and heat transfer coefficients with the vorticity fields in the lamella, which lead to particular mixing processes in the boundary layer region. The correlation between the resulted temperature fields and the droplet dynamics was obtained by assuming a relation between the vorticity and the local heat transfer coefficient, in the first fluid cell i.e. near the liquid-solid interface. The two measured fields revealed that local maxima and minima in the vorticity corresponded to spatially shifted local minima and maxima in the heat transfer coefficient, at all stages of the droplet spreading. This was particularly clear in the rim region, which therefore should be considered in future droplet spreading models. KeywordsDroplet impact, smooth heated surface, high-speed infrared thermography, VOF, vorticity. IntroductionUnderstanding the fluid dynamic and heat transfer mechanisms of droplet impact on heated surfaces is relevant for a wide range of applications, from fire sprinklers to cooling applications. A popular solution for microprocessors cooling is based on spray impingement [1-2]. The elementary representation of a spray composed by arrays of single droplets impacting onto a heated surface is not straightforward in many of the aforementioned applications, but the complexity of the observed phenomena relays on the study of single droplet impacts to understand the basic governing processes. Such approximation is not so far from the real systems for microelectronics cooling, which actually deal with single droplets or with very sparse sprays [1,3]. In many of these applications, liquid phase change is promoted to take advantage of the latent heat of evaporation. However, efficient cooling can be ...

show abstract

Characterization of the topography and wettability of English weed leaves and biomimetic replicas

Cited by 28 publications

References 29 publications

Wettability and Other Surface Properties of Modified Polymers

Wettability and Other Surface Properties of Modified Polymers

Characterization of irregularly micro-structured surfaces related to their wetting properties

Experimental and numerical study on sensible heat transfer at droplet/wall interactions

Contact Info

Product

Resources

About