Surface Energy Research Papers - Academia.edu (original) (raw)

The aim of this paper is to demonstrate that atomistic simulations can be used to evaluate the structure of mineral surfaces and to provide reliable data for forsterite surfaces up to a plane index of 2 using the code METADISE. The methods used to calculate the surface structure and energy which have more commonly been used to study ceramics are briefly explained as is a comparison with experimental data, most notable the crystal morphology. The predicted morphologies show that all the methods (Donnay-Harker, Attachment energies and equilibrium) show most of the surfaces that are expressed in observed crystals. The equilibrium morphology calculated from the relaxed surface energies is the only method which expresses the {201} surfaces and the {101} surfaces, which appear only upon relaxation. The more stable surfaces are shown to be those which have the highest surface density and more closely resemble close packed structures with highly coordinated surface ions and silicon as far from the surface as possible. The most stable surfaces the {100} which has alternating layers of MgO and SiO 2 terminating with an MgO layer. The structure is similar to the MgO {100} surfaces and has a similar energy (1.28 Jm Ϫ2 compared to 1.20). The second most stable are the {201} which have a stepped surface topology, but is also compact with a relaxed surface energy of 1.56 Jm Ϫ2. The results indicate that atomistic simulation is well suited to the prediction of surface structure and morphology although care must be taken in choosing potentials which model the structure and elastic properties accurately. Surface methodology The basic approach, used within the METADISE program (Watson et al. 1996), is to consider the crystal as a

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- Materials Engineering, Geochemistry, Chemistry, Surface Structure

A generalization of the single soil layer variable infiltration capacity (VIC) land surface hydrological model previously implemented in the Geophysical Fluid Dynamics Laboratory general circulation model (GClVO is described. The new model is comprised of a two-layer characterization of the soil column, and uses an aerodynamic representation of the latent and sensible heat fluxes at the land surface. The infiltration algorithm for the upper layer is essentially the same as for the single layer VIC model, while the lower layer drainage formulation is of the form previously implemented in the Max-Planck-Institut GCM. The model partitions the area of interest (e.g., grid cell) into multiple land surface cover types; for each land cover type the fraction of roots in the upper and lower zone is specified. Evapotranspiration consists of three components: canopy evaporation, evaporation from bare soils, and transpiration, which is represented using a canopy and architectural resistance formulation. Once the latent heat flux has been computed, the surface energy balance is iterated to solve for the land surface temperature at each time step. The model was tested using long-term hydrologic and climatological data for Kings Creek, Kansas to estimate and validate the hydrological parameters, and surface flux data from three First International Satellite Land Surface Climatology Project Field Experiment intensive field campaigns in the summer-fall of 1987 to validate the surface energy fluxes.

- by xu liang
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- Environmental Science, Heat Transfer, Multidisciplinary, Land Cover

Cellulose nanofibers with a size range of 5–100 nm have the potential to be a low cost renewable material that has application in a range of products. However, current chemical methods to produce crystalline nanofibers suffer from low yields and high chemical costs, while mechanical methods require high energy costs. Methods to lower the energy costs of the mechanical methods have not been well documented in the literature. A bleached softwood kraft pulp was processed using a mechanical dispersion mill and a homogenizer to produce cellulose nanofibers. Two different commercial enzymes were used to pretreat the wood fibers before the mechanical treatments. The resulting nanofibers were characterized by light microscopy, atomic force microscopy, and inverse gas chromatography. Results indicate that the dispersion mill does not affect the overall pulp fiber fibrillation, but does help prepare the sample for the homogenizer. Most fibrillation occurs after three passes through the homogenizer. The enzyme pretreatment has little effect on the size of the fibers, but does allow for higher solids to pass through the homogenizer without clogging. The dispersion component of surface energy of the resulting nanofibrils is impacted by the type of enzyme used. The measurement of acid–base properties proved to be challenging using current IGC experimental protocols.

- by Nazia Siddiqui
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- Mechanical Engineering, Chemical Engineering, Technology, Biotechnology

The mathematically ill-posed problem of solving linear Fredholm integrals of the first kind for distribution functions, given experimental data, is performed with an iterative maximum-likelihood method called expectation-maximization (EM). The algorithm is programmed on two supercomputers of different architecture: the 4096 processor MP-2 from MasPar Corporation and the 32 processor CM-5 from Thinking Machines Corporation. Parallelization and use of the matrix-vector routines supplied by the vendors provides substantially faster run-times than that executed with the sequential code by other mainframe computers. This increase in computation efficiency provides a more practical use of the EM algorithm for these types of problems, which has been shown to be an optimal method. The MP-2 outperforms the more powerful CM-5 until the dimensions of the problem become fairly large. t Present address:

- by Brett Stanley
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- THEORETICAL AND COMPUTATIONAL CHEMISTRY, Surface Energy

In situ scanning tunneling microscopy (STM) and reflection high energy electron diffraction (RHEED) were used to characterize mercury film electrodeposited onto a Pt(1 1 1) electrode at room temperature. Depending on the amount of Hg deposit, two different growth modes were observed. At low Hg coverage, crystalline (0 0 0 1)Hg adlayer accompanied by 30 •-rotated (1 1 1)-Pt patches was found on Pt(1 1 1). Deposition of multilayer Hg resulted in layered PtHg 2 and PtHg 4 amalgams, which grew epitaxially by aligning their (2 0 1) and (11 0) planes, respectively, parallel to the Pt(1 1 1) substrate. The preference of these epitaxial relationships for the electrochemically formed Pt-Hg intermetallic compounds on Pt(1 1 1) could result from minimization of the surface energy.

- by Shuehlin Yau
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- Engineering, Chemistry, Scanning tunneling microscopy, Physical sciences

The surface energy of cement paste components (calcium silicate hydrate [C-S-H], ettringite and portlandite) before and after treatment with an organic coating has been characterised by X-ray photoelectron spectroscopy (XPS) and inverse gas chromatography at 35°C using n-alkanes, 1-alkene, chloroform, tetrahydrofuran, diethyl ether and CCl 4 molecular probes. Complementary investigations on the interfacial chemistry were also conducted by Fourier transform infrared spectroscopy and Differential scanning calorimetry analyses. Changes in the dispersion contribution to the surface energy (c d s ) and acid-base interaction energies were found to be significantly reduced by the organic coating. The XPS allowed the surface chemistry changes induced by the organic coating to be monitored. In particular, the C1s spectra were peak fitted in order to deduce the contribution of the organic coating materials to the total carbon content on the surface. This study showed not only the existence of hydrate-hardener donor-acceptor adduct formation but also presence of interactions between the hydroxide groups OH of the epoxy and portlandite.

Talc samples in both sheet and powder form are studied by adsorption calorimetry and adsorption isotherm techniques. A model is used to determine the solid surface energy, the solid surface tension and the dispersive, acidic, and basic components of these terms. These results are introduced in an approximate equation relating adsorption to contact angle data. Experimental contact angles are in correct agreement with this approach. The Neumann equation of state is used to fit the data and discussed. It appears as a numerical form of the general equation taking into account gas adsorption and film pressure. Behaviors of talc in contact with liquids do not appear very different whether the solid is in sheet or powder form. C 2002 Elsevier Science (USA)

- by Harold Malandrini
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- Engineering, Modeling, Immersion, Enthalpy
- by Afshin Falsafi
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- Materials Science, Viscoelasticity, Contact Mechanics, Contact angle

An effective interatomic potential consisting of two- and three-body covalent interactions is used here to study the properties of gallium phosphide by molecular dynamics simulations. The many-body interatomic potential accounts for the energy scale, length scale and mechanical properties of GaP. At atmospheric pressure, the calculated melting temperature, linear thermal expansion, vibrational density of states and specific heat are in excellent agreement with experimental results. The structural phase transition induced by hydrostatic pressure at 27 GPa is also in quite good agreement with experimental findings. We also studied the energy of vacancy formation in the GaP lattice and the surface energy, which is in reasonable agreement with experimental data.

- by Adalberto Picinin
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- Materials Engineering, Physics, Condensed Matter Physics, Nanotechnology

We consider surface modulations in epitaxial growth and study the formation of facets. Thereby the dynamics is assumed to be essentially interface-controlled and driven by a strongly anisotropic surface energy together with the incoming flux and modeled by a geometric evolution equation, which leads to facets and corners in the corresponding Wulff-shape. This interface evolution law, which is derived from a curvature dependent interfacial energy, is solved numerically using parametric finite elements. The numerical results indicate two basic stages for the formation of facets and corners. First, a rather periodic structure of hills and valleys is formed, being in agreement with the most unstable wavelength of the linearized dynamics. At the second stage, three distinct morphologies emerge, depending on the growth rate of the surface: faceting and coarsening occurs, periodic patterns emerge, or the surface becomes rough. Moreover, in the first case, the only coarsening event is a kink ternary, i.e. a coalescence of two kinks and one antikink resulting in a kink. r

- by Frank Hausser
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- Crystal Growth, Epitaxial Growth, Finite Element, Chaos Theory Evolution Equation

This paper aims to provide an exhaustive and comprehensive overview on flame treatment as a valuable technique for improving the surface properties of polymers, especially polyolefins. It starts with a brief historical excursus on the origin of flame treatment, and the second section deals with the major fundamentals of flame chemistry, with a special focus on the combustion process and mechanism of surface activation. The most important parameters influencing the extent of the oxidation reaction along with relevant practical notes are discussed in the third section. The concluding section outlines how the most significant features of flame treatment can be profitably used to improve the wettability and adhesion properties of polyolefin surfaces, especially from the perspective of developing novel composite solutions such as polyolefins/bio-based coating pairs intended for many different applications.

- by Stefano Farris
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- Engineering, Science and Technology, Polymer, Wettability

Because of downsizing of electronic products and cost effectiveness, rigid substrate-flexible substrate (RS-FS) bonding technology using ACFs becomes more important as an alternative to socket type connectors and rigid/flex substrates. However, formation of process related bubbles, entrapped inside the ACF layer during bonding processes, is strongly influenced by process variables, such as a bonding pressure and a bonding temperature. These bubbles can reduce adhesion strength of ACFs joints, and induce moisture penetration path and entrapment location during reliability tests in humid environments. However, the causes of bubbles formation during the ACF bonding process and the effect of bubbles on ACFs joints reliability have not been fully understood.

- by Kyung-Wook Paik
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- Surface Roughness, Plasma Treatment, Cost effectiveness, Surface Energy
- by John Tsibouklis
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- Engineering, Advanced Materials, Physical sciences, CHEMICAL SCIENCES

This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright

- by Ivan Vlahinic
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- Materials Engineering, Mechanical Engineering, Civil Engineering, Materials Science

We describe a new surface treatment to obtain optical films for liquid crystal display (LCD) applications. The films consist of a phaseseparated layer including a fluorine-containing (FC) compound and a widely used polymer resin for providing a hard coating after surface treatment of the optical film. The major features of the resulting configuration are high durability with a good hardness of above 4H and a surface that allows oily contaminants such as ink and fingerprints to be easily removed by gentle dry wiping, owing to the antismudge function of the FC compound with a low surface energy. #

- by Il Jeon
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- Mathematical Sciences, Physical sciences, Surface treatment, Phase Separation

Uniaxial creep-to-rupture tests were performed on T91 in air and in flowing lead-bismuth eutectic melts. Compared to specimens tested in air, the specimens tested in liquid-metal show: (i) strain and strain rate increase up to a factor of about 50 (strain rate); (ii) time-to-rupture decrease; (iii) rapid transition into the third creep stage at high stress (above 180 MPa). The analysis of the test results revealed several important surface phenomena, which lead to different behavior of the specimens tested in lead-bismuth eutectic melts compared to those tested in air. Under high stress, and therefore high strain, the crack propagation process is mostly controlled by the reduction of the surface energy due to Pb and Bi adsorption on the steel surface. Under low stress (140 and 160 MPa) and low strain, this process is delayed due to the competing mechanism of healing the oxide scale cracks.

- by Annette Heinzel
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- Materials Engineering, Materials Science, Nuclear Materials, Strain Rate

Contact angle measurements (captive bubble technique) were used to determine the surface energy of three experimental thin-film composite nanofiltration membranes and a commercial nanofiltration membrane (Hydranautics NTR 7450). The two experimental membranes of practical interest were thin film composites (diblock copolymer on a polysulfone support layer). The two blocks were poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) and poly(1,1-dihydroperfluorooctyl methacrylate) (PFOMA). The concept was to devise a membrane material that takes advantage of the low adhesion of PFOMA to prevent fouling and the hydrophilic nature of PDMAEMA to produce high water permeation rates. Hydranautics NTR 7450 is a sulfonated polysulfone membrane that purportedly lessens fouling because the surface is more hydrophilic. The change in surface energy upon wetting, permeation of water containing natural organic matter (NOM) and chemical cleaning was of interest. Wetting caused reorganization of the experimental block copolymer surface to move more of PDMAEMA block to the membrane-water interface. After permeation of ultrapure water, however, the surface became more hydrophilic. After permeation of NOM containing water, the surface of both experimental and commercial membranes reached about the same surface energy, indicative of adsorption of NOM. The contact angle measurements were used to calculate a negative change in surface free energy for all but the PFOMA membrane; hence, with this exception, the deposition of NOM into a layer adjacent to the membrane surface was spontaneous. Scanning electron micrographs and atomic force micrographs showed that rigorous chemical cleaning failed to remove the NOM. Although the new polymeric materials were not more resistant to NOM fouling than commercial membranes, the surface energy calculations may help in the search for more successful polymers. Systematic study of charge, molecular size and specific functional groups of NOM on membrane fouling warrants further research to understand why similar fouling occurred on very different polymeric materials.

- by Francis DiGiano
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- Engineering, Membrane Science, Block Copolymer, Nanofiltration

For some twenty years the marine coatings industry has been intrigued by polymer surfaces with low adhesion to other materials, especially to the biological glues used by marine organisms. Polymers with fouling release surfaces have been made from sundry materials, and their resistance to marine fouling in both static and dynamic tests has been evaluated in the world's oceans. Although the polymer surface property most frequently correlated with bioadhesion is its critical surface tension (), resistance to fouling is also influenced by other bulk and surface properties of the polymer. This paper reviews the types of bonding associated with polymeric materials used in fouling resistant coatings, describes the removal process in terms of fracture mechanics, and discusses the importance of surface energy, elastic modulus and coating thickness in the release of biofoulants.

- by Irwin Singer
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- Materials Science, Technology, Fracture Mechanics, Adhesion

R2R (Roll to roll) printed electronics has been an attractive technology for the mass production. Therefore, many research works have been focused on an optimal flexible substrate, ink formulation, printing process, curing method for a conductive ink in printed electronics applications. However, they did not relate their analysis with the system parameters of R2R continuous printing systems. In this paper, it is found that a printed pattern geometric quality which affects functional quality of printed electronic device could be changed with respect to operating tension of bare substrate even if local optimized ink, substrate, and printing process were applied. Additionally, ink transfer mechanism for R2R printed electronics is analyzed regarding a dynamic surface energy of a bare substrate under a tension in R2R printing systems. With the aim of an efficient prediction of the thickness of R2R printed patterns for given operating conditions, a simple meta-model is developed by using the design of experiment (DOE) method. Also, the proposed meta-model has been verified by several experiments. Through the results, it is presented that how to find an optimal operating tension in R2R printed electronics for guaranteeing a required thickness of R2R printed patterns.

- by Nguyễn Đức
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- Mechanical Engineering, Applied Mathematics, Quality Control, Mass production

Continuous atmospheric plasma oxidation (APO) was used to introduce oxygen functionalities to the surface of carbon fibres in an attempt to enhance interfacial adhesion between carbon fibres and polyamide-12 (PA-12). APO only affects the surface properties of the fibres while their bulk properties remained unchanged. Contact angle and f-potential measurements demonstrated that APO-treated fibres became significantly more hydrophilic due to the introduction of polar oxygen-containing groups on the fibre surface, which also resulted in an increase of surface energy on the carbon fibres. The interfacial shear strength of single carbon fibre/PA-12 model composites, determined by single fibre fragmentation tests, showed an increase from 40 to 83 MPa with up to 4 min of APO treatment time which confirms that the fibre/matrix interfacial adhesion was enhanced. This highlights that the incorporation of APO into composite manufacturing will allow tailoring of the fibre/ matrix interface.

- by Seckin Erden
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- Chemical Engineering, Plasma Chemistry, Contact angle, Model Composition

Atomic force microscopy (AFM) is capable of solid surface characterization at the microscopic and submicroscopic scales. It can also be used for the determination of surface tension of solids (γ ) from pull-off force (F ) measurements, followed by analysis of the measured F values using contact mechanics theoretical models. Although a majority of the literature γ results was obtained using either Johnson-Kendall-Roberts (JKR) or Derjaguin-Muller-Toporov (DMT) models, re-analysis of the published experimental data presented in this paper indicates that these models are regularly misused. Additional complication in determination of γ values using the AFM technique is that the measured pull-off forces have poor reproducibility. Reproducible and meaningful F values can be obtained with strict control over AFM experimental conditions during the pull-off force measurements (low humidity level, controlled and known loads) for high quality substrates and probes (surfaces should be free of heterogeneity, roughness, and contamination). Any probe or substrate imperfections complicate the interpretation of experimental results and often reduce the quality of the generated data. In this review, surface imperfection in terms of roughness and heterogeneity that influence the pull-off force are analyzed based upon the contact mechanics models. Simple correlations are proposed that could guide in selection and preparation of AFM probes and substrates for γ determination and selection of loading conditions during the pull-off force measurements. Finally, the possibility of AFM measurements of solid surface tension using materials with rough surfaces is discussed.

- by Paolo Biagioni
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- Engineering, Science and Technology, Polymer, Wettability

Recent trials on diamond-like carbon (DLC) coated medical devices have indicated promise for blood interfacing applications. The literature is sparse regarding structural and compositional effects of DLC on cellular response. An important goal in optimizing bloodinterfacing implants is minimal macrophage attachment, and maximal albumin:fibrinogen adsorption ratio. DLC coatings deposited by PACVD and FAD, were analysed with respect to sp 3 content (EELS), hydrogen content (ERDA), surface composition (XPS), surface roughness (AFM), surface energy, albumin:fibrinogen adsorption ratio, and macrophage viability and attachment. We found that increasing surface roughness and surface energy enhanced the macrophage viability and the albumin:fibrinogen adsorption ratio. We also found that the higher the hydrogen content for a-C:Hs deposited by PACVD, the lower the albumin:fibrinogen adsorption ratio, and macrophage attachment. This suggests that hydrogen content may be an important factor for influencing the biological response of DLC surfaces. Macrophage cells spread well on all DLC surfaces, and the surface results indicated the non-toxic nature of the surfaces on the cells at the time points tested. r

- by Mihail Ionescu
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- Biomaterials, Macrophages, Multidisciplinary, Surface Roughness
- by Andres Leal
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- Engineering, Materials Science, Polymer, Wettability

We demonstrate that interferometric lithography provides a fast, simple approach to the production of patterns in self-assembled monolayers (SAMs) with high resolution over square centimeter areas. As a proof of principle, two-beam interference patterns, formed using light from a frequency-doubled argon ion laser (244 nm), were used to pattern methyl-terminated SAMs on gold, facilitating the introduction of hydroxyl-terminated adsorbates and yielding patterns of surface free energy with a pitch of ca. 200 nm. The photopatterning of SAMs on Pd has been demonstrated for the first time, with interferometric exposure yielding patterns of surface free energy with similar features sizes to those obtained on gold. Gold nanostructures were formed by exposing SAMs to UV interference patterns and then immersing the samples in an ethanolic solution of mercaptoethylamine, which etched the metal substrate in exposed areas while unoxidized thiols acted as a resist and protected the metal from dissolution. Macroscopically extended gold nanowires were fabricated using single exposures and arrays of 66 nm gold dots at 180 nm centers were formed using orthogonal exposures in a fast, simple process. Exposure of oligo(ethylene glycol)-terminated SAMs to UV light caused photodegradation of the protein-resistant tail groups in a substrate-independent process. In contrast to many protein patterning methods, which utilize multiple steps to control surface binding, this single step process introduced aldehyde functional groups to the SAM surface at exposures as low as 0.3 J cm -2 , significantly less than the exposure required for oxidation of the thiol headgroup. Although interferometric methods rely upon a continuous gradient of exposure, it was possible to fabricate well-defined protein nanostructures by the introduction of aldheyde groups and removal of protein resistance in nanoscopic regions. Macroscopically extended, nanostructured assemblies of streptavidin were formed. Retention of functionality in the patterned materials was demonstrated by binding of biotinylated proteins.

- by Getachew Tizazu
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- Photochemistry, Self Assembly, Multidisciplinary, Gradient

Inverse gas chromatography (IGC) has been used to characterise the surface properties of polycaprolactone (PCL) and poly(lactic acid) (PLA). The dispersive component of the surface free energy (γ D S ) was found to be very small for both of them-values close to 30 mJ/m 2 in the case of the PLA and ca. 40 mJ/m 2 for the PCL. The retention times of the n-alkanes, necessary to calculate the dispersive component of the surface energy, were obtained from the maximum, the centre at half height and the centre of mass of the chromatographic peak. While the values obtained using the first two parameters appear not to be affected by the peak asymmetry, in spite of having been obtained above the glass transition temperature of the polymer, the values obtained using the latter have been found to be not reliable. The drawbacks of using n-alkanes with a very small retention time have also been discussed, estimating the error it can introduce in the final results. Finally, the acid-base properties of the two biopolymers were determined using the approaches suggested by Schultz et al. and by St. Flour and Papirer. Although both methods describe the surfaces of PLA and PCL as neutral ones, differences between the values of the parameters K A , K D and S C were obtained.

- by Adam Voelkel
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- Engineering, Technology, Polymers, Poly (lactic acid)

Reliable estimation of the surface energy balance from local to regional scales is crucial for many applications including weather forecasting, hydrologic modeling, irrigation scheduling, water resource management, and climate change research. Numerous models have been developed using remote sensing, which permits spatially distributed mapping of the surface energy balance over large areas. This study compares flux maps over a relatively simple agricultural landscape in central Iowa, comprised of soybean and corn fields, generated with three different remote sensing-based surface energy balance models: the Two-Source Energy Balance (TSEB) model, Mapping EvapoTranspiration at high Resolution using Internalized Calibration (METRIC), and the Trapezoid Interpolation Model (TIM). The three models have different levels of complexity and input requirements, but all have operational capabilities. METRIC and TIM make use of the remotely sensed surface temperature-vegetation cover relation to define key model variables linked to wet and dry hydrologic extremes, while TSEB uses these remotely sensed inputs to define component soil and canopy temperatures, aerodynamic resistances, and fluxes. The models were run using Landsat imagery collected during the Soil Moisture Atmosphere Coupling Experiment (SMACEX) in 2002 and model results were compared with observations from a network of flux towers deployed within the study area. While TSEB and METRIC yielded similar and reasonable agreement with measured heat fluxes, with root-mean-square errors (RMSE) of $50-75 W/m 2 , errors for TIM exceeded 100 W/m 2 . Despite the good agreement between TSEB and METRIC at discrete locations sampled by the flux towers, a spatial intercomparison of gridded model output (i.e., comparing output on a pixel-by-pixel basis) revealed significant discrepancies in modeled turbulent heat flux patterns that were largely correlated with vegetation density. Generally, the largest discrepancies, primarily a bias in H, between these two models occurred in areas with partial vegetation cover and a leaf area index (LAI) < 2.0. Adjustment of the minimum LE assumed for the hot/dry hydrologic extreme condition in METRIC reduced the bias in H between METRIC and TSEB, but caused a significant increase in bias in LE between the models. Spatial intercomparison of modeled flux patterns over a variety of landscapes will be required to better assess uncertainties in remote sensing surface energy balance models, and to work toward an improved hybrid modeling system.

- by Jeppe Kjaersgaard
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- Earth Sciences, Remote Sensing, Climate Change, Production

This work presents a study of superficial properties of polyacrylonitrile (PAN) films obtained by extrusion process. This innovative material was submitted to microwave plasma treatment generated at low pressure. The contact angle was measured with and without treatment in nitrogen and argon plasma, by the pendant drop technique. The work of adhesion was calculated by the Young–Dupré equation. The surface

- by Maria Daniela Oliveira
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- Materials Engineering, Wettability, Plasma Treatment, Nitrogen

The synthesis of functional fluorinated copolymers, containing a reactive lateral group, , is a multistage procedure. Different methods of synthesizing such compounds were developed and optimized to get efficient fluorinated monomers with various functional groups and X spacer. The copolymerization of these functional co-monomers (1) with commercially available fluoroalkenes (2) offers a wide range of novel functionalized fluoropolymers (3) with interesting properties such as: ion-exchange and catalytic properties, cross-linking, solubility, compatibility, better adhesion, etc.

- by B. Ameduri
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- Inorganic Chemistry, Organic Chemistry, Kinetics, Fluorine Chemistry

The nanocomposite energy applications for plasma reactor produced nanoparticles are reviewed. Nanoparticles are commonly defined as particles less than 100 nm in diameter. Due to this small size, nanoparticles have a high surface-to-volume ratio. This increases the surface energy compared to the bulk material. The high surface-to-volume ratio and size effects (quantum effects) give nanoparticles distinctive chemical, electronic, optical, magnetic

- by Alex Kawczak
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- Materials Science, Production, Nanoparticles, Alternative Energy

Siloxane–polyurethane paints were formulated and characterized for coating properties and performance as fouling-release (FR) marine coatings. Paints were formulated at 20 and 30 pigment volume concentrations with titanium dioxide, and aminopropyl-terminated poly(dimethylsiloxane) (APT-PDMS) loadings were varied from 0 to 30% based on binder mass. The coatings were characterized for water contact angle, surface energy (SE), gloss, and pseudobarnacle (PB) adhesion. The assessment of the FR performance compared with polyurethane (PU) and silicone standards through the use of laboratory biological assays was also performed. Biofilm retention and adhesion were conducted with the marine bacterium Cellulophaga lytica, and the microalgae diatom Navicula incerta. Live adult barnacle reattachment using Amphibalanus amphitrite was also performed. The pigmented coatings were found to have properties and FR performance similar to those prepared without pigment. However, a higher loading of PDMS was required, in some cases, to obtain the same properties as coatings prepared without pigment. These coatings rely on a self-stratification mechanism to bring the PDMS to the coating surface. The slight reduction in water contact angle (WCA) and increase in pseudobarnacle release force with pigmentation suggests that pigmentation slowed or interfered with the self-stratification mechanism. However, increasing the PDMS loading is an apparent method for overcoming this issue, allowing for coatings having similar properties as those of clear coatings and FR performance similar to those of silicone standard coatings.

- by Shane Stafslien
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- Materials Engineering, Stratification, Coatings, Titanium dioxide

Chocolate residues staying behind on the mould surface during chocolate bar manufacture are responsible for production losses, and increased processing costs due to equipment cleaning. This study investigates the determining role of surface energy in chocolate adhesion to the mould substrate and the ease of its demoulding. Four materials (quartz glass, stainless steel, polycarbonate, and Teflon) were investigated as mould substrates. A classical contact angle approach was used for the surface energy determination of mould materials. Chocolate-mould adhesion was measured by a simple separation test between the solidified chocolate and a mould probe using a Texture Analyser. The results demonstrated that surface energy of the mould material is a key determining factor of chocolate-mould interaction and has a significant influence on the adhesion of cocoa butter and dark chocolate to the mould. Further analysis has shown that the electron donor component of the surface energy is the main differentiating factor determining the extent of chocolate adhesion. It is concluded that a high surface energy material is generally not favourable for fabrication of the mould. For clean demoulding, the mould material should have a surface energy below 30 mN m À1 and an electron donor component of the surface energy of approximately 15 mN m À1 .

- by Jianshe Chen
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- Food Engineering, Stainless Steel, Contact angle, Food Sciences

The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is a high spatial resolution, multispectral imager with alongtrack stereo capabilities scheduled for launch on the first NASA spacecraft of the Earth Observing System (EOS AM-1) in mid-199 . Data will be obtained in 14 spectral bands covering the visible through the < hermal infrared wavelength region. A number of standard data products will be available to requesters through an on-line archival and processing system. Particular, user-specified data acquisitions will be possible through a Data Acquisition Request system. res0000913 06-09-99 2 0 : 5 7 : 4 0 R.-W 1 4 -0 5 r e s 0 0 0 0 9 1 3 0 6 -0 9 -9 9 2 0 : 5 7 : 4 0 R e v 1 4 . 0 5 The Charlesworth Group, Huddersfield 01484 517077

- by Erfin Elly
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- Geophysics, Remote Sensing, Data Analysis, Carbon Cycle

Calcium carbonate (CaCO3) is an important component of the near-surface environment. Understanding the nature of its precipitation is important for a variety of environmental processes, as well as for the geologic sequestration of anthropogenic carbon dioxide. Calcite is the most thermodynamically stable bulk polymorph, but energy crossovers may exist that could favor the precipitation of vaterite or aragonite with decreasing particle size. The purpose of this study is to determine the surface energy of calcite, which is the first step towards understanding the effect of particle size on thermodynamic stability in the calcium carbonate system. The enthalpies of five well-characterized calcite samples (four nanophase and one bulk) were measured by acid solution isothermal and water adsorption calorimetric techniques. From the calorimetric data, the surface energies of calcite were determined to be 1.48 ± 0.21 and 1.87 ± 0.16 J/m2 for hydrous and anhydrous surfaces. These values are similar to those measured for many oxides but larger than predicted from computational models for idealized calcite surfaces. The surfaces of synthetic CaCO3 particles contain a range of planes and defect structures, which may give rise to the difference between the experimental and modeled values.

- by Tori Forbes
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- Geology, Geochemistry, Thermodynamics, Polymorphism

This study focuses on using remote sensing for comparative assessment of surface urban heat island (UHI) in 18 mega cities in both temperate and tropical climate regions. Least-clouded day-and night-scenes of TERRA/MODIS acquired between 2001 and 2003 were selected to generate land-surface temperature (LST) maps. Spatial patterns of UHIs for each city were examined over its diurnal cycle and seasonal variations. A Gaussian approximation was applied in order to quantify spatial extents and magnitude of individual UHIs for inter-city comparison. To reveal relationship of UHIs with surface properties, UHI patterns were analyzed in association with urban vegetation covers and surface energy fluxes derived from high-resolution Landsat ETM+ data. This study provides a generalized picture on the UHI phenomena in the Asian region and the findings can be used to guide further study integrating satellite high-resolution thermal data with land-surface modeling and meso-scale climatic modeling in order to understand impacts of urbanization on local climate in Asia. #

- by Hung Tran
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- Remote Sensing, Energy, Satellite remote sensing, Climate

Thanks to their low surface energy, fluorinated anti-sticking layers are widely used in UV nanoimprint lithography (UV-NIL) to treat the mold and facilitate its separation from the imprinted resist. However, it has been reported that release properties of the stamp deteriorate with repeated imprint operations. In this paper, X-ray photoelectron spectroscopy is used to study the mechanism of the fluorinated treatment degradation. A specific experimental protocol is used in order to avoid further degradation under X-ray exposure. It has been observed that a large amount of fluorinated molecules are removed in the first imprint steps and deposited on the surface of the imprinted resist. After this first stage, we observed that fluorinated molecules are progressively degraded along their chain during the NIL process.

The relaxations and energies of the (1 0 0), (1 1 0) and (1 1 1) surfaces of (bcc) Fe have been calculated using density functional theory. A plane-wave pseudopotential method was employed. The results demonstrate that for the (1 0 0) surface a contraction of the first (outer) layer is observed while the second and third layers expand perpendicular to the surface plane; for the (1 1 0) surface, the displacements are the same, however, the magnitude of the relaxations is much smaller, showing the surface to be basically bulk terminated; for the (1 1 1) surface the first two layers contract while the third expands, with the magnitude of the relaxations being much larger than for the other surfaces. The surface energy values for the relaxed and unrelaxed surfaces were determined showing the (1 0 0) and (1 1 0) surfaces to have almost identical surface energies with the (1 0 0) being slightly higher followed by the surface. Our results are compared to other experimental and computational studies and generally show good agreement with experiment; an explanation is provided for any differences. The surface models used in this study provide a good basis for future work examining the adsorption of impurities on the surface and the effect of relaxation on adhesion. Ó

- by Irene Yarovsky
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- Condensed Matter Physics, Quantum Physics, Surface Science, Adhesion
- by C. Verdier
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- Materials Engineering, Adhesion, Rheological properties, Surface Energy

Graphene is at the centre of nanotechnology research. In order to fully exploit its outstanding properties, a mass production method is necessary. Two main routes are possible: large-scale growth or large-scale exfoliation. Here, we demonstrate graphene dispersions with concentrations up to ~0.01 mg/ml by dispersion and exfoliation of graphite in organic solvents such as N-methylpyrrolidone. This occurs because the energy required to exfoliate graphene is balanced by the solvent-graphene interaction for solvents whose surface energy matches that of graphene. We confirm the presence of individual graphene sheets with yields of up to 12% by mass, using absorption spectroscopy, transmission electron microscopy and electron diffraction. The absence of defects or oxides is confirmed by X-ray photoelectron, infra-red and Raman spectroscopies. We can produce conductive, semi-transparent films and conductive composites. Solution processing of graphene opens up a whole range of potential large-scale applications from device or sensor fabrication to liquid phase chemistry.

The fracture of the target and projectile during normal penetration is described using a model of chaotic disintegration modifying the theory of chaotic disintegration of liquids. The radius of the locally smallest fragment is calculated equating its kinetic energy of deformation with its surface energy of fracture. The probability of lacunae opening in the target and projectile materials increases near the target/projectile interface. The percolation threshold for this probability determines the boundary of the fractured zone. When this fractured zone reaches the rear surface of the target the fragments can leave it. Mass distribution of the fragments was calculated with the help of percolation theory. Then, the shape of the debris cloud and the direction, velocity and range of its propagation are calculated to estimate vulnerability behind the perforated target.The calculations were compared with results of normal impact experiments performed with tungsten sinter alloy rods (D=20 mm, L/D=6) against 40 and 70 mm rolled homogeneous armor (RHA) at an impact velocity of 1700 m/s and . For observation of the bulging, breakup and fragmentation of the bulge as well as debris cloud formation and expansion, flash X-ray and laser stroboscope techniques have been applied. From the X-ray photographs and soft recovery tests the shape of the debris cloud and velocity field of the fragments as well as the fragment number and mass distributions have been determined, respectively. The calculations predict well the experimental data.

- by Christian Yarin
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- Mechanical Engineering, Civil Engineering, Aerospace Engineering, X Rays

Comparative analysis of salmeterol xinafoate (SX) powders was carried out to define the aerodynamic properties and mechanism of particle dispersion relevant to the use of these materials in dry powder inhalation drug delivery. Particle sizing methodology was evaluated using laser diffraction, time-of-flight and Andersen cascade impactor measurements combined with electron microscopy and surface area determination. Particle interactions, assessed on the basis of powder bulk density and inverse gas chromatography surface energy measurements, were compared with the aerodynamic forces generated by a dry-powder dispersion device. The supercritically produced material showed by a factor of seven reduced tensile strength of the aggregates and indicated a two-fold increase of fine particle fraction deposited in a cascade impactor when blended with lactose. This effect was explained by the reduced particle aggregation at low differential air pressures and flow rates. A relatively small value of aerodynamic stress required to disperse supercritically produced particles in comparison to micronized material comes from: (a) lower bulk density (loose aggregate structure), (b) larger volume mean diameter, (c) larger aerodynamic shape factor and (d) smaller specific free energy of S-SX particles, in this order of priority. It is shown that aggregation between primary drug particles is important for SX/lactose formulations because such aggregates survive the pre-separation impactor stage.

- by Albert Chow
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- Chemical Engineering, Electron Microscopy, Drug delivery, Atmospheric sciences

Using the recently developed expansion formulae for wave structure interaction problems, the scattering of surface water waves by a semi-infinite floating membrane due to abrupt change in bottom topography is analyzed. Both the cases of finite and infinite steps are analyzed. In the present paper, the analysis is based on the linearized theory of water waves and small amplitude membrane response. Combining the linearized kinematic and dynamic surface conditions on the water surface with the dynamic pressure condition on the membrane, a third order differential equation is derived to describe the membrane covered free surface condition. General wave energy relation for wave scattering by floating horizontal membrane is derived by the application of law of conservation of energy flux and alternately by the direct application of Green's second identity. In the floating membrane covered region, the wave energy density is a combination of the kinetic and potential energy density due to the surface gravity waves, and the surface energy density which is due to the existence of the floating membrane on the free surface. Gravity wave transformations due to an abrupt change in bottom topography in the presence of a floating membrane in finite water depth are analyzed based on shallow water approximation. Numerical results are computed and analyzed to understand the wave transformation due to the floating membrane when there is an abrupt change in topography in different cases. r

- by T. Sahoo
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- Civil Engineering, Ocean Engineering, Wave Energy, Kinetics

Interactions of cells with biomaterials dictate their biocompatibility and biofunctionality, and are strongly influenced by surface properties. Moreover, it is important to control cell adhesion to surfaces for biological studies and diagnosis. Surface properties influence protein adsorption in terms of conformation and quantity adsorbed that further affects cell adhesion and proliferation. Several works have demonstrated that wettability influences cell attachment and proliferation. However, most studies have reported the influence of the surface energy of smooth substrates within a limited range of wettabilities. By controlling the roughness and the hydrophilicity of the surface, one can obtain biomimetic substrates with a wettability ranging from superhydrophobic to superhydrophilic. This review intends to summarize recent works, where the interaction of cells with surfaces with extreme wettabilities was investigated. Such information may be relevant in different biomedical and biological applications including diagnosis, cell biology, or tissue engineering.

In this study we fabricated a silicon-based stamp with various microchannel arrays, and demonstrated successful replication of the stamp microstructure on poly methyl methacrylate (PMMA) substrates. We used maskless UV lithography for the production of the micro-structured stamp. Thermal imprint lithography was used to fabricate microfeatured fluidic platforms on PMMA substrates, as well as to bond PMMA lids on the fluidic platforms. The microfeature in the silicon-based (silicon wafer coated with SU-8) stamp includes microchannel arrays of approximately 30 lm in depth and 5 mm in width. We produced various channels without pillars, as well as with SU-8 pillars in the range of 50-100 lm wide and 6 lm in height. PMMA discs of 1 mm thickness were utilized as the molding substrate. We found 10 kN applied force and 100°C embossing temperature were optimum for transferring the microstructure to the PMMA substrate.

- by Mark Tweedie
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- Mathematical Sciences, Physical sciences, Silicon Wafer, Surface Energy

Inverse gas chromatography (IGC) is a versatile and powerful technique for characterizing physicochemical
properties of materials. One such property, the surface energy, plays an important role in the adhesiveness,
wettability, and consequently flotation of minerals. In this work, quartz was chosen as a
naturally hydrophilic mineral, and dodecylamine was used to hydrophobise the surface. To study the correlation
between the surface properties as measured from IGC experiments and flotation, microflotation
experiments were also conducted. It was shown that with treatment by dodecylamine, the surface energy
decreased, as did the work of adhesion to water. The recovery of quartz increased after the treatment,
indicating a correlation between surface energy and flotation response.
The results indicate that IGC has the capability to determine the thermodynamic properties of quartz,
pre- and post-conditioning. Relating the hydrophobicity and flotation of minerals to the surface energy
can be observed from combining the results of IGC and microflotation experiments.

- by Kristian Waters and +1
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- Materials Characterisation, Mineral Processing, Flotation, Quartz

The thermodynamic definitions of work of adhesion and of surface energy are stated and their influence on 'practical' adhesion emphasized. The work of adhesion has long been estimated via contact angle measurements. This paper discusses its measurement via contact mechanics experiments often using the surface forces apparatus, the results of which are analysed using the JKR or DMT equations. Some recent work using these techniques to study monolayers and thermoplastic films is reviewed.

- by David Packham
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- Materials Engineering, Mechanical Engineering, Chemical Engineering, Thermodynamics

The bulk and surface properties of Cu 2 O were studied theoretically at the density-functional level (DFT). The calculated structural parameters, binding energy per Cu 2 O molecule (E u ) and electronic properties were compared with available experimental bulk data. The convergence of the surface energy was investigated for both non-polar (oxygen terminated) and polar (copper terminated) (1 1 1) surfaces. The electronic properties of both surfaces showed that there are surface states both at the top of the valence band and the bottom of the conduction band, indicating strong surface excitons decreasing the band gap. The structural relaxation was investigated for both cases. The study shows that the stoichiometric O-terminated Cu 2 O(1 1 1) surface exhibits minor relaxation, whereas the Cu-terminated surface undergoes extensive relaxation minimizing the surface polarity and indicative of surface reconstruction for this termination.

- by Boubakar Diawara
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- Density-functional theory, Molecular, Reconstruction, Copper

Montmorillonite/polypyrrole (MMT/PPy) nanocomposites, with 15% mass loading of PPy, were prepared by the in situ polymerization of pyrrole in the presence of montmorillonite (MMT) or organo-modified montmorillonite (oMMT) in aqueous solutions containing an oxidant and an anionic surfactant. The morphology of MMT/PPy nanocomposites distinctly differs from that of the untreated MMT as shown by SEM. X-ray photoelectron spectroscopy showed that the MMT/PPy nanocomposite has an MMT-rich surface, whereas the oMMT/PPy nanocomposite surface has a rather organic nature. Due to the organic modification of MMT by the alkylammonium chloride, polymerization of pyrrole at the surface of oMMT is much more efficient in producing a conductive adlayer resulting in an enhancement of conductivity of the oMMT/PPy nanocomposites (1.1 S cm À 1 ) compared to MMT/PPy (3.1 Â10 À 2 S cm À 1 ). The difference in the behaviour of oMMT/PPy and MMT/PPy is interpreted in terms of surface energy minimization by the alkylammonium ions present at the surface of organo-modified MMT. Indeed, the dispersive contribution to the surface energy (c s d ), as determined by inverse gas chromatography at 150 -C, was estimated to be 34.0 mJ/m 2 for oMMT, much lower than the value of 216 mJ/m 2 determined for MMT. D