The following is a list of the abstracts for papers which will be presented in the ELEVENTH INTERNATIONAL SYMPOSIUM ON CONTACT ANGLE, WETTABILITY AND ADHESION. The listing is alphabetical by presenting author. This list is updated continually to add abstracts as they become available and make appropriate corrections. This list may be conveniently searched by using the editor provided with most popular browsers (e.g. Microsoft Explorer, Netscape, Firefox ... etc.)





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Alidad Amirfazli

Novel Approaches to Measure Contact Angles

Meenakshi Annamalai

On the Nature of Wettability of Rare-Earth Oxide Thin Films

Jayashree Bijwe



Exploitation of Contact Angle Measurement Technique to Quantify the Removal Process of Sizing Agent on Graphite Fibres

Edward Bormashenko


 

Plasma Treatment of Silicone Oil-Infused Surfaces Switches Impact of Water Droplets from Bouncing to Tanner-Like Spreading

Edward Bormashenko



New Investigations of Self-Propulsion: Self-Propelled Rotator Driven by the Marangoni-Flow

Edward Bormashenko


Magnetic Field Inspired Contact Angle Hysteresis Drives Floating Polyolefin Rafts

Hy Bui




Evaluation Long Lasting Property of Cosmetic Products by Contact Angle Measurement

Manuel Chamerois



Oil Reservoir Wettability Specificities

P. Cherukupally




Inverse Gas Chromatography for Porous Media Characterization: Surface Heterogeneity and Surface Energy Profiles

Farshid Chini



Huge Enhancement of Lift to Drag Ratio of Hydrofoils Using Piecewise Wettability Change

Sung Kwon Cho



Integration of Liquid Infused Porous Surface (SLIPS) with Electrowetting and Liquid Dielectrophoresis

Chang-Hwan Choi


Spontaneous Spreading of a Droplet on a Solid Surface: the Fundamental Role of Advancing Contact Angle

Frank M. Etzler



Statistical Considerations for the Determination of Surface Free Energy Components Using Contact Angles and Inverse Gas Chromatography

Kevin Golovin

Designing Durable Icephobic Surfaces

Junhui He

Multi-functional Self-cleaning Coatings with Good Robustness, High Transmittance and Superamphiphobicity

Matti Hokkanen

Droplet Adhesion Measurements in the Wetting Characterization of Topographically Complex, Repellent Surface

Youhua Jiang


Droplet Adhesion on Patterned Hydrophobic Surfaces in a Fakir State: Topography-Dependent Effective Contact Line

Chang-Jin “CJ” Kim

Generalized Dynamic Cassie-Baxter Model

Wilfried Konrad


To Melt or Not to Melt - High Temperature Application Based on Structured Surfaces

J. Lawrence


Surface Engineering for the Control of Polyethylene Terephthalate (PET) Wettability Characteristics Using Laser Beam Wavelength

Daniel Lewis



A Framework to Study Heterogeneous Factors that Influence Grain Growth

Zhiwei Liao


Robust Superhydrophilic, Underwater Anti-oil Fouling Coatings from Spray-coated Assemblies of Polymer Grafted Silica Nanochains

Tingyi “Leo” Liu


Measuring Contact Angles on Super-repellent Surfaces with a Consistent Accuracy

Pouria Rezaee Niaraki


Characterizing the Wettability of Wood Surfaces Based on Their Polar-dispersive Properties

Weerapha Panatdasirisuk

Wettability and Absorbability of Electrospun Yarns for Sweat Sensor Smart Cloth

Jack  Panter


Multifacetted Design Optimisation for Superoleophobic Surfaces

Prashant Pendyala

Directional Wetting Transitions During Evaporation on Microcavity Surfaces

Davide Rossi


Determination of the Surface Free Energy of Water Solutions by Solid like Method

Davide Rossi



Evaluation of in Vitro and in Vivo Drug Release and Skin Absorption after the Treatment with Formulations for Topical Use by Contact Angle Method.

Davide Rossi

From a Tensiometric Versus Skin (Tvs) Modeling to Tvs Skin Test

H. Souzandeh

Sisal Fiber/zein Resin Interface: Effect of Plasticizer and Cellulosic Reinforcement

Gerald Takacs


Enhancing the Wettability of Polybenzimidazole (PBI) to Improve Fuel Cell Performance

Prashant R. Waghmare



Drop Deposition Technique under Microgravity Conditions: from Concept to the Working Model

D.G. Waugh


On the Use of Laser Surface Engineering to Modulate Bacterial Adhesion

Thomas Willers



Theoretical Modeling of the Novel Liquid Needle Dosing Method for Contact Angle Measurements

Dehua Yang



Contact Angle Hysteresis of Pressure Sensitive Adhesives due to Adhesion Tension Relaxation

Roe-Hoan Yoon


Hydrophobic Forces in Wetting Films: Measurement and Thermodynamic Analysis

Jure Zigon



Wettability of Wood Surfaces with Waterborne Acrylic Lacquer Stains Adjusted by Dbd Plasma in Air at Atmospheric Pressure



Alidad Amirfazli; Department of Mechanical Engineering 437 Bergeron Bldg York University 4700 Keele St, Toronto, ON, M3J 1P3

 

Novel Approaches to Measure Contact Angles

 

(Abstract not yet available)

 

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Meenakshi Annamalai and T Venkatesan; Nanoscience and Nanotechnology Institute (NUSNNI) – Nanocore, 5A Engineering Drive 1, T-Lab Building, National University of Singapore, Singapore 117411

 

On the Nature of Wettability of Rare-Earth Oxide Thin Films

 

Ultra-smooth epitaxial thin-films of rare earth oxides (REO) were grown using pulsed laser deposition and then characterized using X-Ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS), and atomic force microscopy (AFM). Herein, we report a systematic study of their wettability through both the traditional sessile drop and the novel f-d method. We found that the films were intrinsically hydrophilic (Water contact angle, WCA < 10̊) just after being removed from the growth chamber, but their WCAs evolved with time and exposure to ambient conditions and reached their eventual saturation values near 90̊ (but always stay 'technically' hydrophilic). X-Ray photoelectron spectroscopy analysis was used to further investigate qualitatively the nature of hydrocarbon contamination on the freshly prepared as well as the environmentally exposed REO thin-film samples as a function of the exposure time after they were removed from the deposition chamber. A clear correlation between the carbon coverage of the surface and increase in WCA was observed for all of the rare-earth films. We do not find any relation between electronic configuration of the rare-earth atoms and hydrophobicity as proposed by Azimi et al.

 

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Umesh Marathe and Jayashree Bijwe; ITMMEC, Indian Institute of Technology, Delhi INDIA

 

Exploitation of Contact Angle Measurement Technique to Quantify the Removal Process of Sizing Agent on Graphite Fibres

 

Carbon/graphite fibres are invariably used in structural composites used in various sectors such as aerospace, aircraft, high-end automobiles etc. These fibres are supplied by the manufacturers with a coating of complex mixture called sizing. It is required for various processes such as handling of fibers, weaving into fabric form etc. It is mainly of epoxy, silane, polyurethane based materials. Sizing agents also are useful to enhance the compatibility of fibers with few commercial resins, which are mainly used by the Industries such as epoxy. For other thermo-plastics there may be incompatibility.

Graphite fibers are known to have very smooth surfaces and no functional groups and hence least possibility of making strong interfacial adhesion with the thermoplastic matrices such as Polyether ether ketone (PEEK) Polyether aryl ketone (PAEK) etc. There are various ways to improve this interfacial fiber-matrix bonding and hence interlaminar shear strength (ILSS) of a composite. Surface treatment of such fibres is the most powerful technique and can be categorized as acid-oxidation/KMnO4 oxidation, plasma treatment, rare earth particles treatment, gamma irradiation etc. These methods give multiple advantages - it imparts functional groups (-COOH, -OH etc.) on graphite fibre surfaces, increases the surface roughness of fibres and hence more area by etching, which leads to more mechanical keying of the matrix. In case of treatment by rare earth particles, especially by nano-particles (NPs), they serve as bridges between the matrix and fibres. Before applying any surface treatment, it is very necessary to ensure complete removal of sizing. Effectiveness of surface treatment solely depends on this removal process.

 

In this work, contact angle measurement technique was utilized to understand the presence of sizing on fibres. Two widely reported sizing removal techniques viz. heat treatment and boiling with acetone were employed. In first experiment Graphite fabric was heated at 500̊ C for various durations (30 - 360 minutes in a step of 30 minutes), while in second experiment it was boiled in acetone for various time durations (60-180 minutes in a step of 30 minutes). Contact angle between deionised water drop and heat treated or boiled fabric was measured using sessile drop method. The drop volume and rate was 2 μL and 0.16 mL/s respectively. It was observed that loss of sizing agent on fabric was an inverse function of contact angle. Sized carbon graphite fabric (as received) showed hydrophobic nature with contact angle of 130.34̊. Same fabric treated at 500 ̊C for 360 minutes showed drop in contact angle to 39.69̊. It was observed that acetone boiling technique was not that effective to remove sizing, since it showed hydrophobic contact with contact angle of 103.74̊ even after boiling for 180 minutes. The de-sized fibres were then treated with nitric acid and contact angle measurement process was again done to understand the extent of effects of treatment in terms of etching. The optimally treated fabric was then characterized for matrix pick up and tow tension test.

 

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Edward Bormashenko; Ariel University, Engineering Faculty, Chemical Engineering, Biotechnology and Materials Department, P.O.B. 3, 40700, Ariel, Israel

 

Plasma Treatment of Silicone Oil-Infused Surfaces Switches Impact of Water Droplets from Bouncing to Tanner-Like Spreading

 

Bouncing of water droplets on cold-plasma-treated and non-treated silicone-oil-infused microporous surfaces is reported. Cold plasma treatment of oil-infused surfaces switches the quasi-elastic bouncing to the two-stage spreading, governed at the final stage by the Tanner-like law. Water droplets placed on the pristine silicone-oil infused surfaces are eventually coated with the silicone oil; whereas, water droplets spread on the plasma-treated oil remained uncoated, due to the increase of the specific energy of the silicon oil induced by the plasma treatment. The semi-qualitative analysis of bouncing is introduced.

 

 

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Edward Bormashenko; Ariel University, Engineering Faculty, Chemical Engineering, Biotechnology and Materials Department, P.O.B. 3, 40700, Ariel, Israel

 

New Investigations of Self-Propulsion: Self-Propelled Rotator Driven by the Marangoni-Flow

 

Marangoni-flow driven self-propulsion of various objects, including liquid marbles, superoleophobic micro-boats and plastic tubing was studied experimentally and theoretically. The self-propelled, longstanding rotation of the polymer tubing containing camphor continuing for dozens of hours is reported. The rotator is driven by the solutocapillary Marangoni flows owing to the dissolution of the camphor. The phenomenological model of the self-propelling is suggested and verified. Scaling laws describing the self-propelling are proposed and tested experimentally. The change in the surface tension, arising from the dissolution of camphor, driving the rotator is estimated as 1-3 mN/m.

 

The self-propulsion of a heavy, superoleophobic, metallic boat carrying a droplet of aqueous ethanol solution as a fuel tank is reported. Maximal velocities of the self-propulsion were registered as high as 0.1 m/s. The thermal field formed under the self-propulsion was studied. Both soluto- and thermo-capillary Marangoni flows promote the self-propulsion. The mechanism of the self-locomotion is discussed. The phenomenological model of the process is introduced. The possibility of the non-contact self-propulsion is reported.

 

 

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Edward Bormashenko and Mark Frenkel; Ariel University, Engineering Faculty, Chemical Engineering, Biotechnology and Materials Department, P.O.B. 3, 407000, Ariel, ISRAEL

 

Magnetic Field Inspired Contact Angle Hysteresis Drives Floating Polyolefin Rafts

 

Displacement of floating polymer (polyolefin) rafts by steady magnetic field is reported. The effect is due to the diamagnetic properties of the liquid support (water). Magnetic field (ca. 0.1 T) deformed the water/vapor interface and impacted the interfacial apparent contact angle. This deformation gave rise to the propulsion force, displacing the polymer raft. The velocity of displacement of center of mass of rafts ~ was registered. The effect origins in the contact angle hysteresis enabling the magnetically inspired change in the interfacial apparent contact angle. The semi-quantitative model of the process is suggested.

 

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Hy Bui; Applied Research, R&I, 111 T , Terminal Ave, Clark 07066, LOREAL USA

 

Evaluation Long Lasting Property of Cosmetic Products by Contact Angle Measurement

 

(Abstract not yet available)

 

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Manuel Chamerois; SCR/R&D, TOTAL E&P - Avenue Larribau, 64018 Pau Cedex - FRANCE

 

Oil Reservoir Wettability Specificities

 

Reservoir wettability is known to be one key factor for oil production through its influence on fluids repartition in porous media, diphasic flow, oil recovery rate…

Compared to others wettability topics, oil reservoir have particularities among which:

 

1.     It deals mainly with liquid/liquid behavior. On theoretical point of view, going from a liquid/vapor situation to liquid/liquid one is straightforward, but some pitfalls have to be avoid,

 

2.     It acts jointly with geometric properties of porous space to generate macroscopic behavior. Thus industrial characterization is based on macroscopic saturation evolutions during spontaneous and forced imbibitions and drainage, and includes contact angle hysteresis,

 

3.     Wettability in reservoir results from equilibrium in the crude oil brine rocks system during geological time. Transfer of polar material from the oil to the pore surface is a key mechanism, and its understanding allows to predict reservoir wettability and to imitate it during laboratory experiments,

 

4.     Oil reservoir wettability modification is often mentioned as responsible for low salt injection enhanced oil recovery. Several mechanisms are reported, multicomponent ion exchange, pH variation or double layer extension… but each of them involves a shift toward more waterwet condition.

 

Equilibrium of both mineral and organic components of the system between rocks surface, brine and crude oil dictate wettability status and modification.

 

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P. Cherukupally,1,3 A. Kondor,2 D. R. Williams,3 A. M. Bilton,1 and C. B. Park1

 

1) University of Toronto, 5 Kings College Rd, Toronto M5S 3G8 - Ontario - CANADA

 

2) Surface Measurement Systems LTD, 5 Wharfside, Rosemont Road, Alperton - Middlesex – UNITED KINGDOM

 

3) Imperial College London, 439 ACE Extension South Kensington Campus, SW7 2AZ - London – UNITED KINGDOM

 

Inverse Gas Chromatography for Porous Media Characterization: Surface Heterogeneity and Surface Energy Profiles

 

Remediation of industrial effluents is challenging. Recently, we demonstrated an acid-base polyester polyurethane (PESPU) sponge for adsorption of organic micropollutants from water. The effectiveness of pollutants adsorption onto sponge is directly related to the surface energy heterogeneity. Inverse gas chromatography (IGC), a gas sorption technique, is capable of characterizing heterogeneous sponge and determine the surface energies corresponding to different chemical active sites. Herein, IGC method was used to characterize surface energy profiles of heterogeneous acid-base PESPU sponge for removal of organic micropollutants from water. Both pristine PESPU and surface-modified PESPU sponge were characterized. A series of n-alkanes were injected at finite dilution and applied the Dorris-Gray method to obtain the dispersive energy distribution profile at 30 ̊ðC and 0% RH. The acid-base contributions were determined by injection of mono-polar probes (dichloromethane and ethylacetate) and applying the Van Oss method at the same conditions as dispersive component. The surface modified sponge was the most energetically homogeneous, while the pristine PESPU sponge had a higher acid-base component as well as broader surface energy distributions than the modified foam. The surface energy profiles were used to optimize the adsorption process for various organic micropollutants to enable scalability of the technology.

 

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A. Irannezhad, M. A. Nobakhti, N. Momtaheni, M. H. Fereydoni, S. F. Chini*; Mechanical Engineering Department, University of Tehran, Tehran, Iran.

 

Huge Enhancement of Lift to Drag Ratio of Hydrofoils Using Piecewise Wettability Change

 

Slip velocity of fluids on superhydrophobic surfaces makes them great for drag reduction applications. Although these surfaces decrease the friction drag, they do not necessarily decrease the pressure drag. Furthermore, they may decrease the lift on air/hydro-foils. We are suggesting that „piecewise superhydrophobicity‰ can resolve the issue. We developed a procedure to find the optimum location of superhydrophobic patches on a foil to meet the desired goal, e.g. drag reduction. We divided the surface of a 2D NACA 0012 into 10 sections, where each section may be either superhydrophobic or regular. So, 1024 chromosomes where each has 10 genomes may represent all the cases. The boundary conditions of the hydrofoil in each case are set according to the genomes of the corresponding chromosome. Using the classic genetic algorithm with 30 first generation chromosomes, along with numerical simulations, the lift and drag forces are found. The numerical simulations were performed at chord-based Reynolds number of 100000, as this value is the transition between laminar and turbulent regimes; and angle of attack of 4o to make sure that lift is not zero. The slip velocity was applied via a user-defined function and definition of Navier‚s slip length. Parents of the next generations are chosen using Roulette-wheel approach. After 7 generations, we found the chromosomes which maximize the lift, minimize the drag, and maximize the ratio of lift to drag (the last two share the same chromosome). The piecewise superhydrophobized hydrofoil decreased the drag by 21% and increased the lift by 2.5%. Then we experimentally studied the piecewise-superhydrophobized hydrofoils inside a water channel and verified the numerical results. The superhydrophobic parts were prepared by acid etching followed by silanization on aluminum 6061 alloy and the contact angles were 167.14+3̊.

 

 

 

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Hongyao Geng and Sung Kwon Cho

 

Integration of Liquid Infused Porous Surface (SLIPS) with Electrowetting and Liquid Dielectrophoresis

 

We presents a simple, versatile, droplet manipulation using a slippery liquid infused porous surface (SLIPS) integrated with a coplanar electrode array. This platform was confirmed effective for both electrowetting-on-dielectric (EWOD) driving of conductive liquids (water and BSA protein solution) and dielectrophoretic (DEP) driving of dielectric liquids (propylene carbonate and isopropyl alcohol or IPA) in the open environment. The SLIPS enormously reduces the biological adhesion because of the highly deformable nature of liquid. Biomolecule (e.g., proteins) can move easily on the SLIPS: Anti-biofouling . This property can overcome the burdensome biofouling problem in digital microfluidics, as well as other bio-related devices.

 

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Chang-Hwan Choi; Associate Professor, Department of Mechanical Engineering, Stevens Institute of Technology, Castle Point on Hudson, Hoboken, NJ 07030, USA

Spontaneous Spreading of a Droplet on a Solid Surface: the Fundamental Role of Advancing Contact Angle

 

(ABSTRACT NOT YET AVAILABLE)

 

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Frank M. Etzler; School of Pharmacy, Lake Erie College of Osteopathic Medicine, 1858 W. Grandview Blvd., Erie, PA 16509

 

Statistical Considerations for the Determination of Surface Free Energy Components Using Contact Angles and Inverse Gas Chromatography

 

(Abstract not yet available)

 

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Kevin Golovin; Faculty of Applied Science, School of Engineering, UBC-Okanagan EME 4271, CANADA

Designing Durable Icephobic Surfaces

Ice accretion remains a costly, hazardous concern worldwide. Icephobic coatings reduce the adhesion between ice and a surface. However, only a handful of the reported icephobic systems reduce the ice adhesion sufficiently for the facile and passive removal of ice, such as under its own weight or by mild winds. In this work I discuss two new mechanisms for drastically lowering the ice adhesion strength of a surface: interfacial cavitation and interfacial slippage. These mechanics-based mechanisms allow for the rational design of icephobic coatings with virtually any desired ice adhesion strength. Additionally, icephobic materials utilizing these mechanisms exhibit much improved durability over traditional, lubricant-based surface. We further investigate how exactly interfacial slippage reduces the ice adhesion of polymeric materials, and we propose a universal framework that may be used to predict the reduction in the adhesion of ice to surfaces exhibiting interfacial slippage. This framework allows one to rationally engender icephobicity in essentially any polymeric system, including common thermoplastics. Hence, we present several new, extremely icephobic systems fabricated from a wide range of materials, including common plastics (polystyrene, polyvinylchloride, cellulose, etc.) and sustainable, natural oils.

 

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Junhui He; Functional Nanomaterials Laboratory, Center for Micro/Nanomaterials and Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Zhongguancundonglu 29, Haidianqu, Beijing 100190, CHINA

E-mail: jhhe@mail.ipc.ac.cn

Multi-functional Self-cleaning Coatings with Good Robustness, High Transmittance and Superamphiphobicity

Self-cleaning multi-functional coatings with good robustness, high transmittance and superamphiphobicity are attracting much attention because of their wide potential applications. In the current work, three different nanostructures were assembled sequentially to build highly antireflective superamphiphobic coatings. A typical coating consisted of 5 layers of 20 nm silica nanoparticles, 2 layers of 80 nm hollow silica nanospheres and 3 layers of mesoporous silica nanosheets deposited on glass substrate. For this particular coating, the contact angle was 171o for water, 157o for diiodomethane and 156o for ethylene glycol, respectively. The maximum light transmittance obtained was as high as 96.1% at 530 nm, while only 91% transmitted through blank glass substrate. Simple chemical vapour deposition (CVD) of tetraethyl orthosilicate was then applied to improve the robustness and adhesion-to-substrate of the coating. The contact angle of coating reached 171o for water and 152o for ethylene glycol, respectively. The maximum transmittance measured using an integrating-sphere photometer was 98.7% at 1580 nm. The coatings withstood the 4H pencil scratching test, tape peeling test, sand abrasion test and water-drop impact test. The effects of CVD conditions on the robustness and adhesion-to-substrate of the coatings were also investigated. The multi-functional coatings could overcome the large barriers commonly encountered in practical applications due to their good robustness, high transmittance and superior superamphiphobicity.

Acknowledgements

This work was supported by the National High Technology Research and Development Program (“863” Program) of China (Grant no. 2011AA050525), the Knowledge Innovation Program of the Chinese Academy of Sciences (CAS) (Grant nos KGCX2-YW-370, KGCX2-EW-304-2), the National Natural Science Foundation of China (Grant no. 21271177), and Key Laboratory of Space Energy Conversion Technology, TIPC, CAS.

References

1.     L. Yao, J. He, Prog. Mater. Sci. 61, 94-143 (2014).

2.     Z. Geng, J. He, L. Xu, L. Yao, J. Mater. Chem. A 1, 8721-8724 (2013).

3.     Z. Geng, J. He, J. Mater. Chem. A 2, 16601-16607 (2014).

jifig1.jpg

Fig. 1 Digital image of the S5S’2S’’3 coating with water (A), ethylene glycol (B), diiodomethane (C) and hexadecane (D) droplets on its surface.

 

 

 

 

 

 

 

jifig2.jpg

 

 

 

 

 

Fig. 2 Transmission spectra of blank glass substrate and the S5S’2S’’3 coated glass substrate recorded by an integrating-sphere receiver.

 

 

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V. Liimatainen1, M. Vuckovac1, V. Jokinen1, V. Sariola2, M.J. Hokkanen1, Q. Zhou1, R.H.A. Ras1

1) Aalto University, FINLAND

2) Tampere University of Technology, FINLAND

Droplet Adhesion Measurements in the Wetting Characterization of Topographically Complex, Repellent Surface

Contemporary surface wetting characterization is almost exclusively via optical contact angle measurements of macroscopic sessile droplet. Droplet adhesion measurements have been proposed as an alternative to contact angle characterization as they generally accommodate for greater sensitivity while bypassing some problems of the conventional approach. In particular, we have developed Scanning Droplet Adhesion Microscopy (SDAM) for wetting characterization of highly repellent and topographically challenging surfaces with unpreceded accuracy. The automated system enables systematic wetting mapping of e.g. biological samples.

In this talk, I will overview the experimental methodology utilized in the SDAM methodology, and review some key results of our recent publication (Liimatainen et al., Nat. Commun. 8, 1978 (2017)). Particular attention will be given on the relationship between the droplet adhesion forces and the advancing and receding contact angles, and the benefits adhesion force measurements are able to offer.

 

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Youhua Jiang1, Yujin Sun2,3, Jaroslaw W. Drelich2, and Chang-Hwan Choi1*

1) Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, New Jersey 07030, USA

2) Department of Materials Science and Engineering, Michigan Technological University, Houghton, MI 49931, USA

3) School of Chemical Engineering and Technology, China University of Mining & Technology, Xuzhou 221116, P.R. CHINA

* Corresponding author

Droplet Adhesion on Patterned Hydrophobic Surfaces in a Fakir State: Topography-Dependent Effective Contact Line

Droplet pinning on structured surfaces is controlled by the effective contact line on an individual structure and the global distribution of a contact line along a droplet perimeter. However, how the contour and length of effective contact line change depending on the shapes and dimensions is unclear, limiting the design of patterned surfaces for controlled adhesion. In this study, the effective contact line length for micro-pillared and micro-pored patterns made of hydrophobic material is determined indirectly from droplet adhesion force measurements. The experimental adhesion force, which is associated with the effective contact line length, is compared to theoretical adhesion force with the apparent droplet boundary length. The maximal adhesion forces required to vertically detach water droplets from patterned surfaces, where the contact line recedes homogeneously toward the droplet center, are measured directly. A correlation between the effective contact line length and the structure dimension is determined, and corroborated by the visualization of contact line dynamics. Results show that contact lines on pored surfaces are not significantly distorted from the circular shape of a droplet base and the effective contact line length approaches the apparent droplet base perimeter regardless of structure dimensions. On pillared surfaces, in contrast, the effective contact line length varies with respect to structure dimensions in a complex manner. For the sparsely- and densely-packed pillars, it is equal to the perimeter and diameter, respectively, while it decreases with the structure size-to-pitch ratio for pillars packed moderately.

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Chang-Jin “CJ” Kim; Micro and Nano Manufacturing Lab; California NanoSystems Institute, Mechanical and Aerospace Engineering Department; Bioengineering Department, University of California, Los Angeles (UCLA)

Generalized Dynamic Cassie-Baxter Model

Modified Cassie–Baxter models have been reported in recent years to address the limitation of the original model. Typically, however, a modified model predicted some but not the majority of the experimental data in the literature. Noting that most models were based on a 2D principle whereas the experiments were performed in 3D world, first we create a 2D experiment to be able to assess 2D principles. While 3D experiments measure the receding contact lines averaged over space and time, our 2D experiment eliminates the spatial averaging and further minimizes the temporal averaging. The details of the contact line motion obtained from the 2D experiments lead us to propose a 2D model, which incorporates the contact-line friction. The resulting 2D model matches the 2D experimental results excellently, while all existing models show significant deviation. Furthermore, by introducing a line solid fraction term, the 2D model is generalized to a 3D model, which successfully predicts the majority of the experimental data in the literature.

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Davide Rossi1,2 ,Paola Pittia2, Nicola Realdon1

1) Department of Pharmaceutical and Pharmacological Sciences, University of Padova, ITALY

2) Department of Bioscience and Technology of Food, Agriculture and Environment, University of Teramo, Italy

Determination of the Surface Free Energy of Water Solutions by Solid like Method

The Fomblin HC-25®PFPE is a biocompatible perfluoropolyether (PFPE) used to characterize formulations for contacting skin & mucous membranes (SFE=18.0 mJ/m2, DC=18.0 mJ/m2, PC=0.0 mJ/m2). Due to the PFPE’s ability to form stable self-repeal films, this work evaluated the suitability of Fomblin HC-25®PFPE fluid film (PFPEf) as a solid test to characterize the Surface Free Energy (SFE; mJ/m2) of aqueous glycerin & sodium chloride solutions by Solid Like Method (SLM) recently developed (Figure 1). The employment of PFPEf as solid test avoid the issues caused by the friction forces at the interface and the roughness ratio that influences the homogeneity of a surface, and consequently affects the measurement of contact angle (CA). On these basis, our work was focused on the development of a method for the tensiometric characterization of dispersed (DC; mJ/m2) and polar (PC; mJ/m2) energy components of WmQ water (15MW cm), aqueous solutions of sodium chloride (by titration method using NaCl saturated solution), glycerin (5 to 90 %w/v), sucrose (10 and 40 %w/v), and hot spring waters (HSW) (Euganean Thermal Area - ETA, Abano Terme, Padua, Italy) using PFPEf as solid test as well as the conventional substrates silica glass (sg), polyethylene (pol), and Fomblin HC/18®PFPE (PFPE2) (SFE=10.5 mJ/m2, DC=8.3 mJ/m2, PC=2.2 mJ/m2). The calculation method used for sessile drop CA’s measurements was Young-Laplace (Y-L) and Owens&Wendt as mathematical conversion model. Measures of conductivity were carried out on the NaCl solutions while glycerol solutions were tested for their viscosity. The SFE of WmQ was determined as first. In Figure 2 the interface profile of a drop of WmQ contacting PFPEf. Figure 2 shows a visible deformation of the film fluid surface with the formation of the characteristic meniscus with size and shape defined. To calculate PC and DC of WmQ, the baseline for contact angles measurement was firstly positioned at the interface A/L/F (air/liquid/fluid) between the air/WmQ/PFPEf (no meniscus = nM) and subsequently at the PFPEf surface at the meniscus base (meniscus = M). The set of solids tests was completed with smooth surfaces silica glass (sg) and polyethylene (pol). To calculate the DC of WmQ, the bi-dimensional characterization of the meniscus was achieved through determination of the differential Δ between the values __of CA measured at the base of the meniscus (ACM) and at the interface A/L/F (ACnM) (ΔWmQ=ACM- ACnM=18.1YMBOL177\f"Symbol"\s122.6). The DC (20.0 mJ/m2) of WmQ was calculated by a novel integrative equation here developed (DC= DCnMWmQ) while its PC (49.2 mJ/m2) corresponded to the value calculated positioning the baseline at nM level. The SFE, DC, and PC of WmQ resulted lower but comparable with the reference parameters of deionized water (DW) (SFE=72.8 mJ/m2, DC=21.8 mJ/m2, PC=51.0 mJ/m2). In the same way, were calculated the Δ values for NaCl solutions in DW (ÆNaCl 45dp =16.0+0.4 deg), DW (ÆDW=19.9+1.1 deg) aqueous solutions of glycerol 98% in DW (Δgly 50% =19.6±3.0), sucrose 10% solutions in DW (ÆS10%=19.19+1.72 deg), sucrose 40% solutions (ÆS40=23.07+1.97 deg) in DW, and natural HSW (Δ=18.6±1.4). The analysis of the correlations between tensiometric and physic-chemical data demonstrated the suitability of the Solid Like Method (SLM) for a rapid and non invasive characterization of the tensiometric properties of water and its solutions using CA method. (e.g. conductivity vs Δ NaCl ;R2=0.97, Δ NaCl vs [NaCl]; R2=0.95, Δgly98% vs [glycerol 98%]/viscosity; R2=0.93, DC NaCl vs Δ NaCl; R2 = 0.99, DC gly98% vs Δ gly98%; R2 = 0.77).

 

contact11-abs.gif

Fig.1: The Solid Like Method

contact11-abs1.gif

 

Fig. 2: Air/WmQ/PFPEf (A/L/F) interface

profile

 

 

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Nicola Realdon1 and Davide Rossi1,2

1) Department of Pharmaceutical and Pharmacological Sciences, University of Padova, ITALY

2) Department of Bioscience and Technology of Food, Agriculture and Environment, University of Teramo, ITALY

Evaluation of in Vitro and in Vivo Drug Release and Skin Absorption after the Treatment with Formulations for Topical Use by Contact Angle Method.

The investigations performed in the field of drug release and absorption after topical application of different formulations assumes a great relevance. Some studies were focused on the in vivo evaluation of the influence of the nature of the vehicle on the skin penetration of topically applied drugs (Realdon et al. 1995). Others investigations highlighted the influence of the vehicle on release and simulated absorption of drugs using in vitro systems in order to find a correlation between in vivo and in vitro data (Realdon et al. 1996). On the basis of these studies, it was demonstrated that the ointment composition influences differently both release andabsorption of drugs as methyl nicotinate (MN) independently from the concentration. In this work the correlation between the contact angles (CA) measured on the surface of four topical formulations (O/W, W/O, Polyethylene Glycol, Lipogel) and in vitro drug release data were investigated. In order to evaluate the link between the skin hydration and the erythema induced by the absorption of MN, CA measurements were also performed on the epidermis surface of four subjects test before and after the application of O/W, W/O, Polyethylene Glycol, Lipogel formulations added with the drug. At the end were correlated in vitro drug release and simulated skin absorption with CA measured on skin surface. The result of these investigations showed the link between the concentration of released MN in time (t15, t90, t180 min) and the tensiometric characteristics of the formulations tested, considering diiodomethane and glycerine as liquids test, in function of the kind of soaked membranes used (water and isopropylmiristate) (Figure 1) in the invitro tests. In the case of diiodomethane, the increase of the correlation degree in the time (t15=0.0309; t90=0.8694; t180=0.973) demonstrated the improvement of the drug release performances of the formulations in time.

As regard the investigations on in vivo absorption, it was demonstrated that the behaviour of erythema is inverse proportionally with CA measurements performed at the interface between the liquids test (formamide; R2=0.99, diiodomethane; R2=0.98, benzil alcohol; R2=0.99) and W/O, Lipogel, and PEG formulations. The analysis of the correlations between the concentration of the in vitro drug released and the CAs measured at the interface between the liquids test and the formulations, demonstrated the possibility to evaluate the condition (intended as concentration of MN released in time) in which each formulation reach its best performance in drug release. At the end, the analysis of the correlation between CA and intensity of induced erythema demonstrated the link between the tensiometric properties of the ointment formulations and the skin erythema induced after their applications in relation to their skin hydration performances.

rossii~1.gif

 

 

 

 

 

Fig. 1: correlation between CA measurementS performed on the formulations and the concentration of MN released in time (water)

 

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Antonio Bettero1,2 and Davide Rossi2,3

1 -C98-TVS Network srls, Padova, ITALY.

2 -Department of Pharmaceutical and Pharmacological Sciences, University of Padova, ITALY.

3-Department of Bioscience and Technology of Food, Agriculture and Environment University of Teramo, ITALY.

From a Tensiometric Versus Skin (Tvs) Modeling to Tvs Skin Test

Thanking to its skin-biocompatibility, the PFPE was employed for the first time in tensiometry as a liquid test for the development of a tensiometric model for the determination of the Surface Free Energy of skin called Tensiometric Versus Skin (TVS) modeling. The TVS modeling was developed on in vitro and in vivo skin by CA method. The in vitro investigations were performed measuring the CAs of diiodomethane, ethylene glycol, methanol and water on the epidermis and the stratum corneum isolated from human skin after explant. Applying the model of Owens-Wendt-Rabel-Kaelbe (OWRK) was possible to determine the SFE (mJ/m2) of these substrates with a satisfactory correlation degree between CAs and the corresponding polarity ratio of the liquids test used (R2 » 0.95). In order to determine the SFE on in vivo human skin, the diiodomethane was substituted with the biocompatible PFPE because its toxicity. The in vivo investigation were performed in two steps. The first step regarded the tensiometric aspect of the model and the second one the diagnostic phase. Within the tensiometric step, the basal CAs in time of a drop of PFPE on in vivo skin surface of a subject test after 10s from its deposition on the surface (CAPFPEt0 = 58.7 deg; CAPFPE10s = 31.2 deg) and the CAs of water after the same time (CAH2Ot0 = 76.1 deg; CAH2O10s = 76.0 deg) were measured. These basal measurements were repeated on a first panel test of 72 subjects demonstrating high reproducibility in PFPE’s CAs (CAPFPE10s = 32.77±1.91) and high variability in the water’s CAs measured in the same conditions (CAH2O10s = 83.4±20.0 deg). The high reproducibility of CAPFPE measured after 10s evidenced the absence of physic chemical interaction at the interface with skin and its measurability at the end of the distension of the drop is possible thanks to the particular repellent properties of Fomblin HC-25. On the base of these observations, the value of CAs measured at PFPE/skin interface after 10s was considered as reference data (0 point) because expression of the absence of tensiometric affinity with the skin. On the base of these observations, we assumed the CAPFPE10s value as constant (CAk = 32.77 deg) while the high variability of the CAs of water depended from the variations of the moisturizing state of the skins tested. The hydration state of the skin is correlated with the functionality of the epidermal barrier of each subject. CAPFPE10s and the values of CAH2O10s were inserted both in the Owens&Wendt (OWRK) model for the determination of the dispersion (DC; mJ/m2) and polar component (PC; mJ/m2) of skin. In this way was possible to employ water as unique liquid test for the determination of the normalized Polar Component (named CPn; mJ/m2) of in vivo skin. The development of the tensiometric step opened at the diagnostic phase (named Tenskinmetry) based mainly on the determination of the CPn determination that is closely correlated to the epidermal functionality state and the aging critical level (acl) of the skin. In order to evaluate the modulations of CPn at native level, the specific reactivity (Rs) of the skin and its functional recovery (R) were assessed by repeating CAH2O10s measurements after a biomimetic activation using a suitable “skindecoder” device containing an liposomial dispersion. The analysis of the variations of CPn in function of the skin activation with “skindecoder” liposomial dispersion was called TVS skin test. The TVS skin test carried out on large scale (N=5039) and in different skin type conditions will be reported.

 

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H. Souzandeh and A. N. Netravali;  Dept. of Textiles and Apparel, Cornell University, Martha Van Rensselaer Hal, Room 289, Ithaca NY

Sisal Fiber/zein Resin Interface: Effect of Plasticizer and Cellulosic Reinforcement

(Abstract not yet available)

 

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Katerine Vega,1 Matthew Cocca,1 Han Le,1 Marc Toro,1 Anthony Garcia, 1 Andrew Fleischer,1 Joel Shertok,1 Michael Mehan,2 Surendra K. Gupta,3 and Gerald A. Takacs*,1

1) School of Chemistry and Materials Science, Rochester Institute of Technology, Rochester, NY, USA

2) Xerox Analytical Services, Xerox Corporation, Webster, NY, USA

3) Department of Mechanical Engineering, Rochester Institute of Technology, Rochester, NY, USA

Enhancing the Wettability of Polybenzimidazole (PBI) to Improve Fuel Cell Performance

  Polybenzimidazole (PBI) is a high-performance polymer having high thermal stability, chemical resistivity, and mechanical strength making it suitable for many applications, such as, in high temperature proton exchange membrane fuel cells (HT-PEMFCs) where PBI film is doped with phosphoric acid (H3PO4) to promote proton transfer via hydrogen bonding between the phosphoric acid and the nitrogen-containing groups in PBI.

Therefore, to increase the surface properties and retention of the phosphoric acid by hydrogen bonding, this research investigated the surface modification of PBI film with polar functional groups formed from the reaction of atomic oxygen produced downstream from a microwave plasma of an Ar/O2 mixture.

The surface modification of the PBI surface was characterized by X-ray photoelectron spectroscopy (XPS), water contact angle (CA), and Atomic Force Microscopy (AFM) measurements to determine changes in chemistry, hydrophilicity, and surface roughness, respectively, as a function of treatment time. Thermal Gravimetric Analysis (TGA) was used to monitor the retention of phosphoric acid to the modified PBI surface.

 

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Aleksey Baldygin1, Ryan Baily1, Ali-Reza Salehi1, Muhammed Khan1, Md Farhad Ismail, Megnath Ramesh1, Nigel Rodrigues1, Thomas 2, Prashant R. Waghmare1

1) interfacial Science and Surface Engineering Lab (iSSELab), Department of Mechanical Engineering, University of Alberta, Edmonton, CANADA, T6G 2G8

2) Applications & Science Department, KRÜSS GmbH, Hamburg, Germany, 22453

Drop Deposition Technique under Microgravity Conditions: from Concept to the Working Model

We present the experimental and theoretical analysis of drop deposition technique for the micro-gravity conditions, which can be expanded to study numerous capillarity driven phenomenon in the microgravity environment. The in-house devised set-up has been successfully tested under the microgravity condition for drop deposition and spreading. A dynamic drop spreading process was collected during parabolic flight campaign at the NRC facility in Ottawa. The obtained results provided a preliminary understanding of the dynamics of spreading which warrants more experimental evidences.

 

 

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D.G. Waugh and J. Lawrence; School of Mechanical, Aerospace and Automotive Engineering, Faculty of Engineering, Environment and Computing, Coventry University, Gulson Road, Coventry, CV1 2JH, UK

On the Use of Laser Surface Engineering to Modulate Bacterial Adhesion

Bacterial attachment to a surface is initiated by the absorption of molecules to the surface of a substratum forming what is known as a conditioning film. Furthermore, bacteria have evolved to become proficient at adapting to not only their extracellular but also environmental conditions, resulting in major health concerns and economic burden in both hospital and industrial environments. The benefits of CO2 and KrF laser surface engineering on the physical properties of polyethylene terephthalate (PET) films, and the subsequent effects on microbiological growth and conditioning film formation are presented. The influence of interfacial wetting on initial conditioning of the CO2 laser surface engineered PET film was analysed using contact angle measurements. Thereafter, the equation of state approach was used to explain the relationship between laser engineered surface characteristics, wettability characteristics and conditioning film formation. Bacterial adhesion analysis revealed a modulated bacterial response to the CO2 and KrF laser engineered patterns. This work presents the viability of laser surface engineering for creating anti-bacterial and bacteria-reactive surfaces, highlighting the potential for implementation of laser surface engineering in both the medical industry and food manufacturing industry.

 

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Farhad Ismail3, Raymond G. Sanedrin2, Thomas Willers1, Prashant Waghmare3

1) KR†SS GmbH, Borsteler Chaussee 85, 22453 Hamburg, GERMANY

2) KR†SS USA, 1020 Crews Road, Suite K, Matthews, NC 28105, USA

3) Department of Mechanical Engineering, University of Alberta, Edmonton, CANADA

Theoretical Modeling of the Novel Liquid Needle Dosing Method for Contact Angle Measurements

contact11-abs2.gif

For accurate and repeatable contact angle measurements (CA), the drop deposition technique is a critical. Recently, the so-called “liquid needle” method has been introduced. [1] Briefly, a sessile drop is built up from a continuous liquid jet without the use of a solid needle. While it has been shown that CA results are identical between solid and liquid needle dosing on a wide range of representative substrates and instruments with implemented liquid needle drop deposition are already widespread, a theoretical model to describe the process of drop deposition by liquid jet has been lacking. We present such a theoretical model for liquid needle drop spreading, considering the transferred jet energy to surface and gravitational potential energy with viscous dissipation term. An energy balance approach, as introduced by Erickson et al. [2] was used with required modifications. The model allows accurate prediction of the development of drop diameter over time during drop spreading, as verified by experimental results obtained for different combinations of dosed liquids and solids. We will comment on the limitation and the advantage of such novous technique with the help of a phase diagram.

Furthermore, we will show some examples where the CA as measured after traditional drop deposition is intrinsically falsified due to additional forceful wetting caused by capillary waves triggered in the drop pinch-off process. High-speed recordings of both drop deposition techniques will explain why in these particular cases the liquid needle provides the reliable CA and the traditional solid needle does not.

References:

[1] M. Jin et al., Colloid Polym. Sci., vol. 294, no. 4, pp. 657, Apr. 2016.

[2] D. Erickson et al., Colloids Surfaces A Physicochem.Eng. Asp., 2001.

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Naoto Shiomura1, Takashi Sekine1 and Dehua Yang2

1)Kyowa Interface Science Co., Ltd., 5-4-41 Nobitome, Niiza, Saitama 352-0011, Japan (shiomura@face-kyowa.co.jp; sekine@face-kyowa.co.jp)

2) Dehua Yang; Ebatco, 7154 Shady Oak Road, Eden Prairie, MN 55344, USA (dyang@ebatco.com)

Contact Angle Hysteresis of Pressure Sensitive Adhesives due to Adhesion Tension Relaxation

Surface free energy (SFE) is widely adopted in the field of adhesive study. Generally speaking, the greater the SFE is the stronger the adhesiveness is. However, the SFE of the acrylic adhesives, a kind of Pressure Sensitive Adhesives (PSA), can be as low as that of Teflon and silicone rubber while it is known that Teflon and silicone rubber are typical materials with low adhesiveness. Further, PSAs could measure 90-130 degrees of contact angles with water through sessile drop technique, which resembles hydrophobic material surfaces. Obviously it is not appropriate to evaluate the adhesiveness of PSAs only using the SFE analysis and conventional sessile drop contact angle measurements.

 

Dynamic contact angle experiments by means of Wilhelmy plate method have been used to study contact angle hysteresis of the PSAs. Increases and changes of contact angle hysteresis were found among the PSAs studied. To better explain the phenomena observed, Adhesion Tension Relaxation (ATR) was introduced and employed. The changes of adhesion tension (Lcos = S - SL) along time or the relaxation under advancing status is believed to reflect the reorientation of the PSA segments when they are in contact with water, as a result of molecular rearrangement of multicomponent polymeric systems in order to minimize interfacial tension in response to environmental medium changes.

 

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Wilfried Konrad(a), Christoph Neinhuis(a), Jörg Adam(b) and Siegfried Konietzko(c)

 

(a) Technische Universität Dresden, Institute for Botany, Zellescher Weg 20 B, 01062 Dresden, Germany

(b) VDEh-Betriebsforschungsinstitut GmbH, Sohnstraße 65, 40237 Düsseldorf, Germany

(c) Hundt & Weber GmbH, Birlenbacher Strasse1, 57078 Siegen, Germany

 

To Melt or Not to Melt - High Temperature Application Based on Structured Surfaces

 

Blast furnace tuyeres are double-walled, water-cooled pipes supplying the blast furnace with huge amounts of required hot air to keep the reduction and melting process running. Tuyere failure is mainly caused by melting of the wall after direct contact with liquid iron, resulting in the partial shut down of the blast furnace and huge energy losses.

 

As a new approach to avoid tuyere failure we developed a new type of tuyere surface with (i) defined cone shaped indentations and (ii) a heat resistant zirconium/corundum coating. This combination results in "ferrophobic" properties i.e. liquid iron of 1500̊ C shows a contact angle exceeding 130 degrees. Theoretical considerations indicate that liquid iron does not infiltrate these indentations completely if the cone geometry is chosen appropriately. Since heat conductivity of the remaining gas trapped inside the cones is very poor and since densely packed cones reduce the contact area between liquid iron and tuyere, heat flow into the tuyere is substantially reduced and therefore the outer walls are much less prone to melting.

 

It can be shown that the realization of this scenario requires two conditions to be fulfilled: (i) the maximal cone diameter should not exceed the capillary length (which is around 0.48cm for liquid iron), and (ii) the difference between contact angle and the half opening angle of the cone should exceed 90 degrees. If valid, these conditions guarantee that a gas/liquid iron interface within a cone can exist in the first place, that it is mechanically stable against small perturbations and that the formation of such an interface requires less energy than the infiltration of the complete cone with liquid iron.

 

These predictions have been tested experimentally: about 10 liters of liquid iron were poured onto two quadratic copper plates (side length about 50cm, thickness 5cm), one equipped with the cone shaped indentations described above, the other one with a smooth surface. The plain plate burned through after a few seconds, the prepared one, however, suffered no damage and its temperature did not exceed 220̊C. As a result, the new surface is a promising step towards longer lasting blast furnace tuyeres and, consequently, the reduction of energy loss in steel production.

 

 

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J. Lawrence* and D.G. Waugh; School of Mechanical, Aerospace and Automotive Engineering, Faculty of Engineering, Environment and Computing, Coventry University, Gulson Road, Coventry, CV1 2JH, UK

*Corresponding author: E-mail: jonathan.lawrence@coventry.ac.uk, jl-laserengineering@hotmail.com

Surface Engineering for the Control of Polyethylene Terephthalate (PET) Wettability Characteristics Using Laser Beam Wavelength

Herewith are further discoveries into the science and technology behind using laser beam wavelength and the subsequent manipulation of polar component (through atmospheric oxygen content) to control the contact angle behaviour of the surface of polyethylene terephthalate (PET). The findings indicate that the theory will be applicable to most polymers. When exposed to infrared (IR) CO2 laser irradiation the PET surface experienced no change in chemistry and, therefore, no change in polar component occurred. There was, however, topography change to produce a rougher surface; consequently, contact angle followed the Wenzel, etc. theories and increased, changing the surface from hydrophilic to hydrophobic. In contrast, ultraviolet (UV) KrF excimer laser beam radiation altered both the topography and chemistry of the PET surface. The very nature of processing polymers with UV laser radiation inherently generates a surface that is more oxygen-rich with enhanced functional groups, which cause an increase in its polar nature. This UV laser irradiation–induced enhanced polar nature has more of an effect than topography for polymers, which, in turn, effects a decrease in contact angle. In this instance the PET surface became more hydrophilic. We now have a new science-based platform from which to assess, research and establish the methodologies for wettability characteristics modification through controlled laser beam exposure.

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Daniel Lewis; Materials Research Center, Room 110, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180

 

A Framework to Study Heterogeneous Factors that Influence Grain Growth

 

Grain growth has been a subject of study in the processing and microstructure of materials for many years. Recent advances have focused on three-dimensional topology, three-dimensional microstructure reconstruction and three dimensional kinetic models. Much of our understanding to date is based on assumptions of uniform boundary mobility and surface energy. In this talk I will describe an enhanced framework for study of grain growth when the key factors of mobility, surface energy and curvature are not uniformly distributed in the microstructure. I will present some early modeling results and some ideas for future study.

 

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Zhiwei Liao; University of Pennsylvania, Chemical and Biomolecular Engineering,Philadelphia PA 19104

Robust Superhydrophilic, Underwater Anti-oil Fouling Coatings from Spray-coated Assemblies of Polymer Grafted Silica Nanochains

Surfaces that have superhydrophilic characteristics are known to exhibit extreme oil repellency under water. Scalable manufacturing of such coatings that can be applied onto various surfaces is attractive for many applications including water-oil separations and anti-fouling coatings. In this work, we create a robust superhydrophilic coating that repels oil under water by controlling surface chemistry and assembly morphology. The coating is obtained by spray coating poly(acrylic acid) (PAA)-grafted SiO2 nanochains onto substrates, leading to the formation of a porous membrane with nanoscale roughness and large porosity. By comparing the wetting properties of these PAA-grafted SiO2 nanochain assemblies to other types of structures, we show that both the morphology created by spray-coating of nanochains and the surface grafting of PAA are necessary to enable robust underwater superoleophocity. In addition to superhydrophilicity (water contact angle in air ≈ 0°) and underwater superoleophobicity (underwater oil contact angle ≥ 165°), the polymer-grafted nanochain assembly exhibits extremely low contact angle hysteresis (< 1°) and small adhesion hysteresis (≈ -0.05 mN/m), and thus oil can readily roll off from the surface. More interestingly, we show that even after the PAA grafted nanochain coating is purposely impregnated with oil, oil can be readily and spontaneously removed from the coating within about 10 seconds when placed under water. Our approach offers a facile yet effective method to create a robust superhydrophilic and anti-oil fouling coating via a scalable manufacturing method.

 

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Tingyi “Leo” Liu; Department of Mechanical and Industrial Engineering, University of Massachusetts Amherst, MA

Measuring Contact Angles on Super-repellent Surfaces with a Consistent Accuracy

The popularity of superhydrophobic surfaces has made measuring very large contact angle (> 150°) of water droplets much more common. The advent of superomniphobic surfaces has further expanded the range of repellable liquids to many low surface tension and small capillary length liquids such as oils and solvents. To properly characterize the wettability of those super-repellent surfaces, dynamics contact angles are required but they are generally more difficult to measure. Not only because there is no theoretical profile exists for fitting, the sessile drops of liquids are also severely sagged by gravity due to increasingly smaller capillary lengths. Here we report that, when measuring such large contact angles, existing methods have a systematic error that has not been noticed until now. While negligible for most liquids today, this error becomes appreciable for liquids with extremely small capillary lengths (< 1.0 mm), which became repellable only recently on a truly superomniphobic surface that can super-repel even fluorinated solvents. We propose that, to assess a CONSISTENT accuracy in measuring the contact angles of various liquids on a super-repellent surface, a new Bond number defined by the droplet equator height and optical resolution should be kept constant for all measurements.

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Pouria Rezaee Niaraki and Andreas Krausea; Centre of Wood Science and Technology, University Hamburg, Hamburg 21031, GERMANY

Characterizing the Wettability of Wood Surfaces Based on Their Polar-dispersive Properties

In order to find the most compatible approach for wood surface modification, the effect of both mechanical and chemical treatments on wood surface wettability were simultaneously evaluated. For this purpose contact angle measurements were tested on wood veneers (spruce) using two of most applicable models known as Owen-Wendt-Rabel-Kaeble (OWRK) and Van Oss-Chaudhury-Good (vOCG) methods to determine surface free energies. To prepare samples, veneers were firstly divided into two categories of sanded and non-sanded ones. Chemical treatments were then carried out by using either maleic anhydride grafted with polyethylene (MAPE) or butyric anhydride to manipulate the polarity and dispersive properties of wood surfaces. The results showed a general trend of increase/decrease both after sanding and chemical treatments for contact angles and surface free energies respectively. However sanded veneers treated with butyric anhydride had lower contact angles and higher surface free energy than non-sanded veneers with the same chemical treatment. This would suggest that butyric anhydride treatment is not compatible with mechanical treatment at all. In addition, if obtaining a hydrophobic surface is of main importance, MAPE treatment will be more advised than butyric anhydride to form a non-polar surface. The polarity of sanded samples were also increased after chemical treatments which can be attributed to having more surface roughness after sanding and penetration of chemicals from the surface to bulk in wood structure consequently.

Keywords: wetting, surface energy, contact angle, sanding, MAPE, Butyric anhydride, polarity, hydrophobicity

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Weerapha Panatdasirisuk; University of Pennsylvania, Materials Science and Engineering,  Philadelphia  PA 19104

Wettability and Absorbability of Electrospun Yarns for Sweat Sensor Smart Cloth

(ABSTRACT NOT YET AVAILABLE)

 

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Jack  Panter; Durham University, Department of Physics, South Road Durham, Durham DH1 3LE UK

Multifacetted Design Optimisation for Superoleophobic Surfaces

From contaminated water purification to anti-fingerprint displays, the potential applications for physically textured surfaces repellent to low surface tension liquids (superoleophobic surfaces) is vast. The complex structures necessary for superoleophobicity preclude comprehensive experimental and computational studies of the wetting properties. Here, we develop three simulation strategies to take a systematic and multifaceted approach to optimal reentrant and doubly reentrant design. In the contact angle hysteresis study, we discover and provide quantitative models for two high-adhesion receding mechanisms, modelled via capillary bridge rupture. We verify prevailing theories on the low-adhesion receding mechanisms. In the critical pressure study, we show that current models are inaccurate. However, by employing a capillary bridge description, they can be modified to allow accurate predictions for both the critical pressures and their corresponding liquid-vapour interface morphologies. Finally, we study the minimum energy failure mechanisms by developing a rapid and precise energy barrier search process. Overall this simultaneous optimisation is applied to two examples of structures for membrane distillation and anti-microbial surfaces.

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Prashant Pendyala,1 Hong Nam Kim,1, 2 Sung-Wook Yang,1 Il-Joo Cho,1, 2 Eui-Sung Yoon*,1, 3

1) Center for BioMicrosystems, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of KOREA

2) Division of Bio-Medical Science and Technology, KIST School, University of Science and Technology, Seoul 02792, Republic of KOREA

3) Division of Nano & Information Technology, KIST School, University of Science and Technology, Seoul 02792, Republic of KOREA

 Directional Wetting Transitions During Evaporation on Microcavity Surfaces

A range of physico-chemical factors such as substrate surface energy and geometry, thermal distributions, and surface tension of the liquid affect the wetting states and their transitions. Recently, it was reported that the transitions from Cassie to Wenzel states may not be instantaneous or uniform. In this work, we investigate the mechanisms and spatio-temporal distribution of wetting transitions with respect to the surface energy and structure of closed microcavity surfaces. Patterned microcavity surfaces used for the study were fabricated using deep reactive ion etching (DRIE) process. The surface energy of the patterns was varied using diamond-like carbon (DLC), Fluorine incorporated diamond-like carbon (FDLC) and polytetrafluoroethylene (PTFE) coatings. We showed that wetting transitions can be tuned to be either instantaneous or spatio-temporally distributed, by controlling the surface energy and geometry. Importantly, we showed that when the coated surfaces were hydrophobic, evaporating drop under some specific conditions would undergo directional wetting transition, where the cavities near to the 3-phase contact line are filled first. We showed that such transitions were not related to the Laplace pressure. We highlight the role of internal flow dynamics of the drop, resulting from the differential mass transfer of the evaporating drop surface, in the directional wetting transitions.

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Kaiwu Huang and Roe-Hoan Yoon; Center for Advanced Separation Technologies, Virginia Tech, Blacksburg, VA 24061

 

Hydrophobic Forces in Wetting Films: Measurement and Thermodynamic Analysis

 

(Abstract not yet available)

 

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Jure Zigon*1, Marko Petric1 and Sebastian Dahle2

1) University of Ljubljana, Biotechnical Faculty, Department of Wood Science & Technology, Jamnikarjeva 101, 1000 Ljubljana, SLOVENIA

2) Institute of Energy Research and Physical Technologies, Clausthal University of Technology, Leibnizstraße 4, D-38678 Clausthal-Zellerfeld, GERMANY

*e-mail: jure.zigon@bf.uni-lj.si

 

Wettability of Wood Surfaces with Waterborne Acrylic Lacquer Stains Adjusted by Dbd Plasma in Air at Atmospheric Pressure

Better wettability of wood surfaces prior to bonding or coating process can be achieved by treatments with gas discharges. One of the modification methods to reach better penetration, spreading and wettability of applied liquid adhesives and coatings on wood surfaces is the treatment with a dielectric barrier discharge (DBD) plasma. Changes caused on wood surfaces are influenced by many internal and external parameters of the process. In our experiments, a setup generating DBD plasma in ambient air at atmospheric pressure for surface treatment of wood was used. A special emphasis was put on study of water droplet contact angles and evolution of spreading on untreated and treated surfaces. Based on the wettability results, a plasma pre-treatment process was optimized, and interactions of the wood substrate with different liquids and commercial waterborne acrylic lacquer stain coatings applied were studied. Results also showed changes in morphological and chemical properties of untreated and plasma treated wood surfaces. It was shown that plasma treatment increased wettability of wood, which positively influenced the adhesive strength of the coating. Differences in the fracture behaviour of untreated and plasma pre-treated samples, prepared according to different scenarios, were observed.

 

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