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Fluorinated polyhedral oligomeric silsesquioxane (F-POSS) nanoparticles have been widely used to enhance the hydrophobicity or oleophobicity of polymer films via constructing the specific micro/nanoscale roughness. In this work, we study the oleophobicity of pure and F-POSS-decorated poly(vinylidene fluoride) (PVDF) and poly(methyl methacrylate) (PMMA) films using a dynamic density functional theory approach. The role of nanoparticle size and coverage and the chemical features of F-POSS and the polymer film in the wetting behavior of diiodomethane droplets has been integrated to the remaining ratio of surface potential to quantitatively characterize the corner effect. It is shown that, on the basis of universal force field parameters, the theoretically predicted contact angles are in general agreement with the available experimental data.

In this study, microwave plasma was used to treat the surface of Pinus yunnanensis wood under the conditions of 220 V of input voltage, 20 μA of filament current, 8.8 mW of output power, 11 mW of reflected power, 2450 MHz of frequency, and 700 Pa of vacuum. The microwave plasma presented very significant treatment effects on the treated surface, even under weak treatment conditions, for example long treatment distance of 120 mm and short treatment time of 60 s. The treated surface showed better surface wettability, and the contact angles on the treated surface measured from deionized water, glycerin, and diiodomethane decreased sharply, even decreased to 0°. The treated surface also presented higher surface free energy, for example, 61.4–62.8 mJ m−2, being greatly improved by microwave plasma compared to that of untreated surface of 46.5 mJ m−2. The bond strength of the treated surface was 7.34 MPa, about 16 % higher than 6.31 MPa for untreated surface. The best treatment effect was obtained for the treatment distance of 120 mm and treatment time of 60–300 s. This technique might be widely used in wood modification and wood processing.

The measurements of the contact angle of the aqueous solutions of n -octyl-β- d -glucopyranoside (OGP) and monorhamnolipid (RL) on polytetrafluoroethylene surface (PTFE) as well as the water, diiodomethane and formamide on the PTFE covered by the OGP and RL layer were made at 293 K. On the basis of the obtained contact angle the values of the critical surface tension of the PTFE wetting, adhesion work of the solutions to the PTFE and the adsorption of the OGP and RL at the PTFE–water interface were calculated. The tendency of OGP and RL to adsorb at the PTFE–water interface was considered by determination of the standard Gibbs free energy of adsorption of these surfactants. To determine this energy, a new equation was proposed which was based on the critical micelle concentration of surfactants (CMC), surface tension and contact angle of solution at the CMC. The values of the standard Gibbs free energy of OGP and RL adsorption were compared to those determined by using the Langmuir and Gu and Zhu equations. It was stated that there is the good agreement between these values calculated in different ways. These values are close to those determined for the OGP and RL at the water–air interface.

The fluorinated polyesters with different fluoroalkyl groups were synthesized from phthalic anhydride, epichlorohydrin, and fluorinated glycidyl ether. The structures of the modified polyesters were well characterized by proton and fluorine nuclear magnetic resonance (1H NMR and 19F NMR). Contact angle measurement was used to investigate the surface wettability. The results showed that the introduction of an extremely low concentration of fluorine content into the coatings resulted in a significant increase in contact angle of water or diiodomethane, and decrease in the surface energy. X-ray photoelectron spectroscopy (XPS) showed that the F/C molar ratio on the surface was much higher than that in the bulk, indicating the surface enrichment of fluoroalkyl groups. It was also found that fluorinated polyester with longer fluoroalkyl groups had a higher tendency to enrich on the coating surface. In addition, the chemical composition of the inner layer in near-surface area was also investigated by XPS equipped with argon bombarding. The enrichment of fluoroalkyl groups was supposed to occur in near-surface area.

The effect of phospholipid DPPC monolayer on surface properties of powdered quartz (SiO 2 /DPPC ML ) and silicon wafer (Si/DPPC ML ) before and after phospholipase A 2 (PLA 2 ) action was determined. DPPC on quartz particles was deposited from chloroform solution and the monolayer on silicon surface by using the Langmuir–Blodgett technique. The surface free energy and its components of powdered quartz before and after contact with PLA 2 in NaCl solution were determined by imbibition–drainage method (I–DM), which is based on the capillary rise method. The probe liquids (water, formamide and diiodomethane) wick the powder bed. The DPPC monolayer supported on silicon after the contact with NaCl or Tris solution (without and with enzyme PLA 2 ) was monitored by contact angle measurements of the probe liquids. In order to visualize the changes in the DPPC monolayer structure, its topography images were obtained from AFM. The obtained results show that most evident changes in wettability, i.e. the apparent surface free energy of DPPC monolayer supported on silicon (Si/DPPC ML ) and treated with PLA 2 occur within the first 15 min after initiation of the hydrolysis. The analysis of the topography images of the phospholipid monolayer clearly reveals that degradation of monolayer occurs. The modification of quartz powder with DPPC resulted in decreased apparent surface free energy, which however increased after the PLA 2 action, up to the value obtained for bare quartz surface. This again revealed the hydrolysis reaction. The influence of PLA 2 on the surface free energy changes of DPPC monolayer deposited on silicon correlated with those observed for quartz powder. These results pointed out a complete hydrolysis of DPPC by PLA 2 enzyme. The AFM images shed more light on the relation between DPPC monolayer topography and the apparent surface free energy changes taking place during the hydrolysis catalyzed by PLA 2 .

The objective of this work was to determine surface properties of biopolymer film as a function of temperature and/or after plasma treatment with the aim of further wettability tests and biocompatibility. The examined biopolymers were native starch and starch modified by solution of PC (phosphatidylcholine). Contact angles for polar water (and formamide) and nonpolar diiodomethane on the glass plates covered with starch film before and after gelatinization (25 °C, 37 °C and 60 °C) were measured for the base and plasma modified film. The surface free energy of solid (gel) was determined from the advancing and receding contact angles of these probe liquids, using the contact angle hysteresis model (CAH). The plasma treatment was immediately followed by a sharp decrease of contact angle and in the course of ageing the contact angle also decreased due to the reorientation of polar groups into the polymer surface layer. To depict better changes in hydrophilic/hydrophobic character of the starch surface before and after modification the work of water spreading, W S was calculated. A sharp decrease in negative values of W S takes place which indicates more hydrophilic character of starch surface after modification. Surface morphology and roughness were studied by optical profilometer and FTIR measurements which confirm the contact angle results. It was also proved that a combination of input treatment parameters led to improvement of biopolymer wettability and provided possibilities of starch application where uniform thin films are required.

The effect of O2 addition in the gas feed of an open-to-air N2–O2 dielectric barrier discharge (DBD) on the surface modification of sugar maple hardwood samples is reported. After treatment by N2–O2 plasma, an increase of the contact angle with water and a decrease of the contact angle with diiodomethane was observed. X-ray photoelectron spectroscopy and Fourier-transform infra-red analyses further reveal a decrease of the O/C as well as increase of the C=O peak and surface aromaticity. When O2 is added to the nominally pure N2 DBD, the discharge transits from a homogeneous regime to a filamentary regime with increased dissipated power and neutral gas temperature. As a result, surface modification by N2–O2 plasmas becomes similar to those occurring under a low-temperature heat treatment of wood surfaces. In such conditions, a mechanism involving the thermally-activated deacetylation and depolymerisation of hemicelluloses and cross-linking between lignin and furfural and hydroxylmethylfurfural, leading to the increase of wood hydrophobicity is proposed.

In this work the effect of short chain iodoalkane solvent additives such as iodobutane, iodoethane, diiodomethane and iodomethane on the photovoltaic parameters of poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) (1:1) based bulk heterojunction (BHJ) solar cells was studied in an ambient air conditions. Devices processed in 2% (v/v) of diiodomethane, iodobutane and iodoethane showed improved power conversion efficiency (PCE) of 2.40, 2.29 and 2.04%, respectively as compared to the efficiency of pristine (without additive) devices (1.93%), while devices made using iodomethane exhibit PCE of 1.66%. The UV–vis absorption spectra of devices showed that the presence of these additives results the growth of enhanced local structure with improved crystalline and order of P3HT domain. Furthermore, UV–vis absorption response of the solar cells before and after soaked in the aforementioned solvents indicates that each additive has selective solubility for PCBM except iodomethane in which both P3HT and PCBM showed solubility.

Measurements of the surface tension of canola oil from different manufacturers, diesel oil and water–oil interface tension as well as the contact angle on different parts of the diesel engine were made. The contact angle for canola and diesel oils on polytetrafluoroethylene (PTFE) and polymethyl methacrylate (PMMA) surfaces as well as for water, diiodomethane and formamide on different parts of the diesel engine was also measured. On the basis of the obtained results as well as the van Oss et al. approach to the interfacial tension and the Young equation the Lifshitz–van der Waals component of the surface tension and electron-donor and electron-acceptor parameters of the acid–base components of this tension of canola and diesel oils and parts of diesel engine were determined. Taking into account the determined values of the parameters and components of the surface tension of diesel and canola oils, their adhesion to the particular parts of a diesel engine was determined by using the van Oss et al. equation and compared to the adhesion work determined from the Young–Dupre equation. It appeared that the adhesion work determined from the van Oss et al. equation which decreased the precursor film pressure is comparable to that determined from the Young–Dupre equation. Adhesion work of the diesel oil to different parts of the diesel engine is somewhat lower than that of canola oils. In addition the water–diesel oil interface tension is lower than that for water–canola oil.

Hierarchical Al surfaces were fabricated using three different kinds of alkaline-based chemical etching processes. The surface morphology changes to a needle-like microstructure or to nanoscale flakes on a microscale porous structure depending on the chemical solution used. These surfaces were characterized by field-emission scanning electron microscopy, X-ray diffraction analysis, X-ray photoelectron spectroscopy, and contact angle measurements. After the hydrophobic treatment, the etched Al surface shows non-wetting properties, exhibiting a static contact angle over 150° and a dynamic contact angle less than 5° for deionized water. Oleophobic properties for diiodomethane and N,N-dimethylformamide are exhibited by all etched Al surfaces.

The main goal of this paper was to determine wettability properties of native starch and starch modified by antibacterial solution of chitosan or lysozyme as a function of temperature and/or after plasma treatment. Contact angles for polar water (and formamide) and nonpolar diiodomethane on glass plates covered with starch film before and after gelatinization (25 °C, 37 °C and 60 °C) were measured. The surface free energy of solid (gel) was determined from the advancing and receding contact angles of these probe liquids, using the contact angle hysteresis model (CAH). The plasma treatment was immediately followed by a sharp decrease of contact angle. In the course of ageing the contact angle also decreased due to the reorientation of polar groups into the surface layer of polymer. Also a sharp decrease in negative values of WS takes place which indicates more hydrophilic character of starch after plasma treatment. The same was after lysozyme modification but to a smaller extent. The opposite trend of changes was visible after chitosan solution treatment. The surface characterization was observed by FTIR measurements and surface topography from the profilometer images and such measurements well support the contact angle results. The arrangement of temperature, plasma treatment or biological modification can lead to improvement of starch surface wettability and stability. The obtained results open up possibilities of starch application in food, paper and packaging industries as well as in pharmacy.

Irradiation of a para-hydrogen (p-H2) matrix containing diiodomethane (CH2I2) and O2 at 3.2 K with light at 280 ± 20 nm, followed by annealing of the matrix at 4.0 K, yielded infrared (IR) absorption lines at 2982.4, 1408.9, 1231.8, 1226.5/1225.6, 1085.6, 917.7, 841.6/841.1, 550.5, and 490.2 cm−1 that are assigned to the syn-iodomethylperoxy (syn-ICH2OO) radical. Further irradiation of the matrix at 365 nm diminished these features. Experiments with CH2I2 and 18O2 yielded lines of syn-ICH218O18O at 1407.3, 1228.1/1227.7, 1217.7/1217.0, 1031.5, 899.9/899.4, 836.7/836.0, and 473.6 cm−1. The assignments are based on the photolytic behaviour and comparisons of observed vibrational wavenumbers, IR intensities, and 18O-isotopic shifts with those predicted with the B3LYP/aug-cc-pVTZ-pp method. The observation is consistent with a mechanism that, upon photolysis of CH2I2 at 280 nm, CH2I was formed and subsequently reacted with O2 to yield syn-ICH2OO. Compared with the gaseous reaction CH2I + O2 → CH2OO + I at low...

A series of apparent advancing and receding contact angles of water and diiodomethane was measured on the phospholipid/cholesterol monolayers physisorbed on the mica surfaces. It was found that the contact angles and their hystereses vary significantly depending on the lipid film composition and mutual miscibility of both components. These changes were much greater for water than diiodomethane. When the phase separation occurred, the hysteresis of water contact angle significantly decreased whereas the diiodomethane contact angle hysteresis increased considerably. Different behavior of both liquids may result from different mechanisms of the liquid droplets penetration/retention and points to structural changes that occur within the monolayers, including molecules rearrangement when exposed to water. The structure of the studied monolayer surfaces was confirmed by means of the microscopic techniques. The images are a visual evidence of cholesterol precipitation out the binary films at their specific stoichiometry. The results provide a new insight into the advancing/receding contact angles origin (and contact angle hysteresis) of polar and apolar liquids depending on the phospholipid/cholesterol monolayer composition, as well explanation of the origin of the contact angle hysteresis on the model biological surfaces, which are molecularly smooth.

An aluminum carbenoid is the efficient cyclopropanation reagent for the transformation of 2-alkenyl amines into cyclopropyl amines. The addition of iodine facilitates the cyclopropanation of poorly reactive 2-alkenyl amines.

The present study evaluates two different methods for selection of probe liquids to determine the surface free energy (SFE) of asphalt binders: (i) Condition Number (CN) of probe liquids, and (ii) plot between cosine of total SFE ( ϒ L Cosθ) and total SFE of probe liquids ( ϒ L ) . Five different probe liquids, i.e. Water (W), Formamide (F), Ethylene Glycol (E), Diiodomethane (D), and Glycerol (G) were selected. Overall, ten different combinations of probe liquid triplets (W-G-F, W-G-E, W-G-D, W-F-E, W-F-D, W-D-E, G-F-E, G-F-D, F-E-D, and D-E-G) were formed to examine CN and plot of ϒ L Cosθ versus ϒ L . Three asphalt binders, namely unmodified (VG30), SBS polymer modified binder (PMB40) and crumb rubber modified (CRMB60) binders were selected for the present study. The contact angle of asphalt binders was measured using sessile drop method, and SFE of each of the selected asphalt binders was determined for all ten combinations of probe liquids. Thereafter, CN of probe liquid triplets was determined using Singular Value Decomposition (SVD) method. In addition, ϒ L Cosθ versus ϒ L plot was made for triplets using the measured contact angles of probe liquids. The CN approach and ϒ L Cosθ versus ϒ L plot were compared based on binder’s total SFE to identify a better approach for selecting appropriate probe liquid triplets. CN approach was observed to be superior compared to the plot of ϒ L Cosθ versus ϒ L . In fact, it was observed that the plot approach may not be valid for asphalt binders.

Diamond-like carbon (DLC) and titanium-doped DLC thin films were prepared by unique hybrid system consisting of pulsed laser deposition, ion source (bombardment) and magnetron sputtering. The influence of deposition parameters (ion energies, deposition pressures and magnetron power) on composition and physical properties was studied. Composition and sp3/sp2 ratio were determined by XPS. sp3/sp2 ratio was in the range from 1.4 to 2.2 for undoped DLC and from 3.4 to 4.8 for Ti-DLC. AFM showed that the layers were smooth, but with small amounts of random droplets. The measurements of the contact angle and determination of surface free energy were made for water, diiodomethane and ethylene glycol. Hardness and reduced Young’s modulus varied from 20 to 31 GPa and from 182 to 276 GPa, respectively. Film adhesion was determined by scratch test; LC3 reached 23 N for DLC and 27 N for TiDLC. Optimization of sp3/sp2 ratio, hardness and adhesion to biomedical alloys will advance the DLC coatings usability in the field of implantology.

Diamond like carbon (DLC) and Ag-doped DLC (Ag-DLC) films were prepared by dual pulsed laser deposition using graphite and silver targets and two KrF excimer lasers. The silver concentration in the films was varied from 1.1 to 9.3 at. %. The surface topography was analysed by atomic force microscopy. The pure DLC was very smooth, but the roughness increased with rising silver content. Ethylene glycol, diiodomethane and deionized water were used to measure contact angles (CA). The measurements for water showed that the CA of Ag-DLC films (78–98°) was higher than that of the DLC film (77°). In order to understand the influence of incorporated Ag on the wettability, the surface energy and the protein adsorption as an indirect measure of the hemocompatibility were calculated. The surface energy of DLC and Ag-DLC films was same. The hemocompatibility was examined by the adsorption ratio of albumin/fibrinogen as an indirect method and improved with the increase of the Ag concentration. The antibacterial activity of the films were evaluated by bacterial eradication tests with Staphylococcus aureus and Pseudomonas aeruginosa at different incubation times. DLC and Ag-DLC films demonstrated good results against Staphylococcus aureus and Pseudomonas aeruginosa, meaning that DLC and Ag-DLC can be useful to produce coatings with antibacterial properties for biomedical devices such as sensors.

Diamond-like carbon (DLC) thin films are frequently used for coating of implants. The problem of DLC layers lies in bad layer adhesion to metal implants. Chromium is used as a dopant for improvement of adhesion of DLC films. DLC and Cr-DLC layers were deposited on silicon, Ti6Al4V and CoCrMo substrates by a hybrid technology using combination of pulsed laser deposition (PLD) and magnetron sputtering. The topology of layers was studied using SEM, AFM and mechanical profilometer. Carbon and chromium content and concentration of trivalent and toxic hexavalent chromium bonds were determined by XPS and WDS. It follows from the scratch tests that Cr doping improved adhesion of DLC layers. Ethylene glycol, diiodomethane and deionized water were used to measure the contact angles. The surface free energy (SFE) was calculated. The antibacterial properties were studied using Pseudomonas aeruginosa and Staphylococcus aureus bacteria. The influence of SFE, hydrophobicity and surface roughness on antibacterial ability of doped layers is discussed.

International audience; To control the wettability of polymer interfaces with water without using perfluorinated chains, the 3,4-ethylenedioxythiophene (EDOT) monomer and its derivatives have been good candidates for surfaces formed by electrodeposition. In this work, a series of original EDOT-based monomers were studied. A carbamate linker was used to introduce alkyl and aromatic substituents onto the EDOT-monomer, and the side groups were found to significantly influence the resulting surface structuration and wettability. As the chain length of alkyl substituent increases, rougher more hydrophobic surfaces form. With significantly long alkyl side groups (>C6), superhydrophobic properties including water contact angles (θwater) up to 158° were observed despite intrinsic hydrophilicity of the polymers. In general the monomers with aromatic substituents formed smoother surfaces. Oleophobicity was tested using diiodomethane, and it was found the wetting state varied with side group: longer alkyl (>C8) and aromatic substituents were completely penetrated by diiodomethane (Wenzel state of wetting), while shorter alkyl substituents followed the Cassie Baxter state. With a relatively facile synthetic route to develop the monomers, these polymers are very attractive for anti-bioadhesion, anti-icing, and anti-fog applications.

Made available in DSpace on 2018-12-11T17:18:47Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-06-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Objective: This study evaluated the capacity of sodium hexametaphosphate (HMP) at different concentrations to alter the surface properties of dental enamel in order to increase calcium and phosphate adsorption. Design: Bovine enamel blocks (4 mm × 4 mm, n = 144, 12/group) were divided: 0%; 0.25%; 0.5%; and 1% HMP, followed or not by application of solutions containing Ca or Ca-PO4, totaling 12 groups. The treatments were performed for 2 min, and the surface free energy (mN/m) was calculated by measuring the contact angles of three probing liquids (deionized water, diiodomethane and ethylene glycol), which was used to determine the polar and nonpolar components of the enamel surface. Calcium (Ca), phosphate (PO4) and HMP in the solutions treatment solutions were analyzed before and after treatment. The data presented normal and homogeneous distribution and then were subjected to ANOVA, followed by Student-Newman Keuls’ test (p < 0.05). Results: The higher the% of HMP in the solutions, the greater HMP adsorption and more electron-donor sites on enamel surface were achieved (p < 0.05). Also, Ca adsorption was higher with increasing% HMP in the solutions (p < 0.05), which in turn reduced electron-donor sites on enamel surface. Increased Ca and PO4 adsorption occurred at 0.5% and 1% HMP after treatment with Ca-PO4 solution, resulting in a less electron-donor sites on surface when compared to the other treatments (P < 0.05). Conclusions: HMP leads to a more electron-donor sites on enamel surface, what promotes greater adsorption of Ca and PO4 ions. São Paulo State University (Unesp) School of Dentistry Araçatuba Department of Pediatric Dentistry and Public Health, Rua José Bonifácio 1193 Araçatuba Federal University of São Carlos (UFSCar) LIEC-Department of Chemistry, Rodovia Washington Luís, s/n São Carlos São Paulo State University (Unesp) School of Dentistry Araçatuba Department of Pediatric Dentistry and Public Health, Rua José Bonifácio 1193 Araçatuba CNPq: 308981/2014-6

Iodination of dissolved organic matter (DOM) initiated by manganese oxide may represent an important source of organoiodine compounds (OICs) for iodide-containing waters. Here, Suwannee River natural organic matter was selected as model DOM, the OICs formation in simulated freshwater samples from iodinated DOM induced by manganese oxide (δ-MnO2) was investigated at different pHs and concentrations of iodide and δ-MnO2 by using negative ion electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR MS). While no OIC was observed in DOM control samples without δ-MnO2, hundreds of OICs were detected in the presence of δ-MnO2, suggesting the enhanced role of δ-MnO2 played in DOM iodination. The relative abundance was defined as the value of dividing the peak intensity of OICs by the highest m/z peak intensity constantly occurred in each mass spectrum, and selected as a parameter for partly reflecting the real level of OICs. The relative abundance of most OICs were around or greater than 1%, and several OICs with higher relative abundance were identified as diiodo-5-hydroxy-4-cyclopentene-1,3-dione, diiodomethane and diiodoacetic acid. The numbers of the formed OICs increased with the increase concentrations of iodide/δ-MnO2 and the decrease of pH, and nearly all OICs formed at lower levels of iodide/δ-MnO2 and/or higher pH were overlapped by that at higher levels of iodide/δ-MnO2 and/or lower pH, indicating the reliability of FT-ICR MS analysis techniques and data processing method. The OICs were formed mainly from the iodination of typical lignin-like and tannin-like compounds, as well as the precursor compounds with higher relative abundance through substitution reactions. Our findings demonstrate that the OICs formation by δ-MnO2-initiated DOM iodination should receive more attention and the concentration, exact structure and toxicity of the OICs need to be further investigated.

We present a novel route for the quick and easy synthesis of a broad range of β-lactams. The synthesis involves a [3+1] cyclization of amide dianions with diiodomethane. In contrast to the seminal work of Hirai et al. from 1979, the reaction proved to be a general and efficient approach towards azetidinones. The ease of the process was confirmed by DFT calculations and its power demonstrated by a diversity-oriented synthesis of β-lactams with four points of diversity determined by the choice of Ugi adducts as starting materials.

A metal-free synthesis of aryl bromides and iodides from anilines via halogen abstraction from bromotrichloromethane and diiodomethane is described. This one-pot reaction affords aryl halides from the corresponding anilines in moderate to excellent yields without isolation of diazonium salts. The transformation has short reaction times, a simple workup, and insensitivity to moisture and air and avoids excess halogenation. DFT calculations support a SRN1 mechanism. This method represents a convenient alternative to the classic Sandmeyer reaction.

Surface modification of cellulose-based paper, which displays roll-off properties for water and oils (surface tension ≥23.8 mN·m–1) and good repellency toward n-heptane (20.1 mN·m–1), is reported. Droplets of water, diiodomethane, motor oil, hexadecane, and decane all “bead up”, i.e., exhibit high contact angles, and roll off the treated surface under the influence of gravity. Unlike widely used approaches that rely on the deposition of nanoparticles or electrospun nanofibers to create superamphiphobic surfaces, our method generates a hierarchical structure as an inherent property of the substrate and displays good adhesion between the film and substrate. The two-step combination of plasma etching and vapor deposition used in this study enables fine-tuning of the nanoscale roughness and thereby facilitates enhanced fundamental understanding of the effect of micro- and nanoscale roughness on the paper wetting properties. The surfaces maintain their “roll-off” properties after dynamic impact tests, demonstr...

The paper deals with the properties of a beech wood surface treated by CO2 laser engraving. The studied concerns were the discoloration, changes to morphology assessed through roughness and waviness parameters, and surface wetting with standard liquids (water and diiodomethane), with the aim of determining the wood surface free energy. The results have confirmed that the studied properties of the beech wood surface varied significantly, which were affected by the laser beam power P and raster density n. With increasing P and n, the lightness L* (expressed in CIE L*a*b* color space) decreased significantly. We also observed significant variation in the color coordinates a* and b*. At 8% laser power, the roughness and waviness parameters measured parallel as well as perpendicular to the grain increased proportionally with the increasing raster density. However, 4% laser power was not associated with distinct changes. Increasing the raster density reduced beech wood surface wetting equally with water and with diiodomethane. This was reflected in the higher contact angle values. The wood surface exhibited higher hydrophobicity at 4% laser power. At this power, the increasing raster density was reflected in the decreasing surface free energy, due to its polar component decrease. At 8% laser power, the changes in surface free energy were very minor from the practical viewpoint. The results suggest a potential good adhesion between film-forming materials and wood. However, the gluing performance may be negatively affected by the high roughness attained at 8% laser power and at higher raster densities.

This study represents the first airborne, in-situ measurements of HC(O)OH in the European Arctic, across the winter and summer seasons. HC(O)OH concentrations are under predicted at present, particularly in the mid to high northern latitudes. Data presented here probe unconfirmed sources of HC(O)OH in the Arctic, and would suggest an ocean source of HC(O)OH is more significant than proposed land sources in both winter and summer environments. A maximum concentration of 420 ppt was recorded over the ocean during the July 2012 campaign. This was more than 1.7 times greater than the maximum land concentration reported. Calculated estimates on HC(O)OH production would suggest diiodomethane photolysis could represent a significant source of HC(O)OH in marine environments in the European Arctic. Enhanced HC(O)OH concentrations observed at altitudes greater than 2 km particularly during the March campaign highlight the significance of long range transport on the European Arctic budget. In addition, two HC(O)OH vertical profiles between the altitudes 0.3–6.6 km are presented to provide a more representative vertical profile for this latitude which may be used to improve forthcoming regional and global modelling of the HC(O)OH budget.

Bis(iodozincio)methane, prepared from diiodomethane and zinc metal in the presence of a lead catalyst, is capable of performing several unique molecular transformations. It can operate not only as a dianion, but also as a bidentate Lewis acid. In this ­account, the methylenation of carbonyl compounds, nucleophilic cyclopropanation reactions, 1,4-addition reactions of bis(iodozincio)methane, and reduction reactions of π-allylpalladium are discussed, along with the associated density functional theory calculations. 1 Introduction 2 Methylenation of Carbonyl Compounds 3 Nucleophilic Cyclopropanation 3.1 Cyclopropanation of 1,2-Diketones 3.2 Asymmetric Construction of Quaternary Carbon Atoms by Stereospecific Cyclopropanation 4 1,4-Addition Reactions of Bis(iodozincio)methane 4.1 Three-Atom Ring-Contraction Reaction 4.2 Enolate–Homoenolate Intermediates and Their Reactions 5 Reduction of π-Allylpalladium Derivatives 6 Conclusions and Outlook

Diiodomethane is used to generate C1 fragments at surfaces, en route to higher hydrocarbons. Here scanning tunneling microscopy was employed to examine the interaction of diiodomethane, CH2I2, with a Cu(110) surface, from 4.6 to 8.8 K. In this temperature range unexpectedly rapid thermal reaction resulted in the rupture of two C–I bonds, yielding pairs of I atoms recoiling in opposite directions. Approximately 65% of the carbene, CH2, product from this highly exothermic (4.1 eV) thermal reaction remained chemisorbed. Two stable physisorbed configurations of diiodomethane were found, “vertical” (75%) and “horizontal” (25%). Electron-induced reaction of these intact adsorbates led to single-electron dissociation of both the C–I bonds, with a minor path leading to single bond breaking to form CH2I. Directed recoil of chemisorbed carbene was observed in approximately half the electron-induced reactive events. Simulation of the electron-induced reaction by the impulsive two-state (I2S) model consistently predi...

Objective This study investigated the impact of sulfuric acid etching duration of PEEK on work of adhesion (WA) with resin composite cements, and compared additionally measured surface parameters to shear bond strength (SBS) results. Methods PEEK specimens were fabricated and divided according to different etching times using 98% sulfuric acid (N=448/n=54): 0, 5, 15, 30, 60, 90, 120 or 300 s, respectively. The resin composite cements RelyX ARC, Variolink II and Clearfil SA Cement (N=54/n=18) were smoothed on a glass plate. The sessile drop method was applied in all contact-angle measurements; distilled water and diiodomethane served as testing liquids. Overall 1350 single contact angle measurements were performed. Thereafter, surface free energy (SFE), WA, interfacial tension (IFT) and spreading coefficient (SC) of all combinations between etched PEEK and resin composite cements were calculated. Data were statistically analysed using Kolmogorov–Smirnov, Shapiro–Wilk tests, descriptive statistics and two-/one-way ANOVA with post-hoc Scheffe test (p Results Variolink II showed the lowest WA, followed by RelyX ARC and Clearfil SA Cement, respectively. Etching specimens for 60 s showed the lowest WA values while etching times between 0 s and 30 s, and 300 s showed higher results. WA values for groups etched for 90 s and 120 s showed no differences when compared to the 60 s groups. SFE and disperse percentage showed a positive correlation with SBS. A negative correlation was observed between SBS and polar percentage for etched PEEK, WA, IFT and SC. Conclusions The WA values do not allow statements about the bond between two materials to be made; other parameters must be taken into account. A waiver of conventional bond test methods is not possible.

Using sol-gel method, the films containing appropriate nanoparticles have a wide range of application as protective, dielectric and superhydrophobic layers. The system “stabilized aqueous SiO2 sol–acetic acid–isopropyl alcohol” was used to study the possibilities of preparation of nanocomposite SiO2 films and their properties. The properties of surface of prepared films, such as morphology, topography and adhesion forces, were studied using atomic force microscopy (AFM). The contact angle of water and diiodomethane was measured to specify the polar and disperse components of surface tension. The changes in observed properties, mainly the difference of samples X4, X5 and X6, are explained on the basis of changes in stabilization process of sols used for films preparation. For the given observed properties, the determining process is the change from electrostatic to steric stabilization of studied sols.

The sol–gel method was used for preparation of TiO 2 sols without and with the addition of “small molecules” — acetylacetone and acetic acid. The TiO 2 films were made by dip-coating method in different time intervals after preparation of sols. Properties of film surface, such as morphology, rms-roughness and adhesion force were studied using atomic force microscopy (AFM). The contact angle of water and diiodomethane was measured for identification of polar and dispersion component of the surface free energy (SFE). From the obtained results, it can be seen that “small molecules” influence the morphology of films. During the first days after the sol preparation, there is the increase of roughness of films prepared from sols with “small molecules” but with the increasing time, the roughness decreases. There is no crystallization of films with acetylacetone. For films prepared from sols with acetylacetone, the polar component of SFE is lower than in the case of films prepared from sols without “small molecules” and with acetic acid. The “small molecules” decrease the stiffness and adhesion force mainly for films prepared several days after sol preparation. This influence is the result of complex effect of “small molecules” on processes occurring during preparation of films, from hydrolysis reaction over process of particle growth to thermal treatment.

In this paper, a low-cost, high-efficiency and high-flexibility surface modification technology for polymer materials was achieved at high laser scanning speeds (600–1000 mm s−1) and using an all-solid state, Q-switched, high-average power, and nanosecond pulse ultraviolet (355 nm wavelength) laser. During the surface modification of a very important engineering plastic, i.e., black bisphenol A polycarbonate (BAPC) board, it was found that different laser parameters (e.g., laser fluence and pulse frequency) were able to result in different surface microstructures (e.g., many tiny protuberances or a porous microstructure with periodical V-type grooves). After the modification, although the total relative content of the oxygen-containing groups (e.g., C O and COO−) on the BAPC surface increased, however, the special microstructures played a deciding role in the surface properties (e.g., contact angle and surface energy) of the BAPC. The change trend of the water contact angle on the BAPC surface was with an obvious increase, that of the diiodomethane contact angle was with a most decrease, and that of the ethylene glycol contact angle was between the above two. It showed that the wetting properties of the three liquids on the modified BAPC surface were different. Basing on the measurements of the contact angles of the three liquids, and according to the Young equation and the Lifshitz van der Waals and Lewis acid–base theory, the BAPC surface energy after the modification was calculated. The results were that, in a broad range of laser fluences, pulse frequencies and scanning speeds, the surface energy had a significant increase (e.g., from the original of about 44 mJ m−2 to the maximum of about 70 mJ m−2), and the higher the laser pulse frequency, the more significant the increase. This would be very advantageous to fabricate the high-quality micro-devices and micro-systems on the modified surface.

The enthalpies of molecular and dissociative adsorption of CH2I2 on Pt(111) at 100–210 K were studied using single-crystal adsorption calorimetry and density functional theory (DFT). Gaseous CH2I2 was found to adsorb on the Pt(111) surface at 100 K to form CH2,ad + 2Iad, with a calorimetric heat of adsorption that decreases with coverage as 222–480θ kJ/mol for θ < 1/8, where θ is the coverage in monolayers (ML), defined as the number of dissociatively adsorbed CH2I2 molecules per Pt(111) surface atom. These coadsorbed iodine atoms greatly destabilize the methylene species even at the lowest coverage, which we attribute to their inability to diffuse away from the near-neighbor sites where they are initially produced on the short time scale of the heat measurement. A mixture of dissociative adsorption fragments of methylene and methylidyne were detected at elevated temperatures between 125 and 190 K. At 210 K, CH2I2 adsorption produced CHad, Had, and 2Iad, with the Iad now able to diffuse away to minimize r...

Background/purpose The purpose of these studies was to determine the surface free energy of the human skin and its critical surface tension of wetting in the skin – surfactant aqueous solution – air system in relation to different types of surfactants. Methods The surface free energy of the skin and its components was calculated using the equilibrium advancing contact angle values of water, formamide, and diiodomethane on the forearm skin surface. Next, taking into account the measured values of the contact angle of aqueous solutions of SDDS, CTAB, TX-100 and TX-114 on the skin surface and data of their surface tension, the critical surface tension of the skin wetting was determined. Results We can classify the skin surface as low-energetic one. The critical surface tension of the skin wetting depends on the type of surfactant. Conclusion It is possible to determine the critical surface tension of the human skin wetting on the basis of the values of the contact angle of aqueous solutions of surfactants and their surface tension. In this respect, nonionic surfactants seem to be the most appropriate.

Self-assembly of ZnX2 (X = Cl, Br, and I) with 2,7-bis(nicotinoyloxy)naphthalene (L) as a hemicircular bidentate ligand containing a chromophore moiety yields a systematic metallacyclodimeric unit, [ZnX2(L)]2. These basic skeletons constitute, via interdigitated π···π interactions, a unique columnar ensemble forming a suprachannel. This can then be employed as an unusual “diiodomethane within the suprachannel” host–guest system, CH2I2@[ZnX2(L)]2. Specifically, the suprachannel significantly stabilizes the CH2I2 molecules in the order [ZnI2(L)]2 > [ZnBr2(L)]2 > [ZnCl2(L)]2. This suprachannel has significant halogen effects on the photoluminescence (PL), thermal properties, and host–guest inclusion.

This Letter presents a low-cost, high-throughput strategy for fabricating size-tunable hierarchical CrN nanohole arrays for a nanomould using a magnetron sputtering approach with nanosphere lithography (NIL)-based technology. The size of the polystyrene nanospheres has a direct influence on the diameter and period of the CrN nanohole structure. The reactive ion etching and magnetron sputtering process can easily control the nanohole size and depth. The hole depth generally depends on the film thickness. The contact angles were measured by the sessile drop method using distilled water, ethylene glycol and diiodomethane. The surface-free energy of the CrN nanomould was calculated using the Owens–Wendt geometric mean approach. This Letter reports the successful fabrication of a series of nanoholes with diameters decreased from 347 ± 9.6 to approximately 166 ± 11.8 nm with a depth of 100 ± 5.6 nm. The corresponding surface-free energy decreased from 40.83 to approximately 24.58 mN/m. The diameter of nanoholes has an obvious effect on the surface-free energy and there is tendency for the surface-free energy to decrease with the decrease in the diameter of the nanoholes. This new approach of ordered CrN nanohole array structures can be used to create a two-dimensional nanomould for NIL.

Copper and silicon substrates were coated by chemical vapor deposition using hexamethyldisiloxane (HMDSO) as the precursor gas. Substrates were placed both at the anode and cathode of a glow discharge reactor, and films were deposited using different self-bias voltages. This study focuses on comparing the differences between the hydrophilicity, polymeric character, chemical structure and nanomechanical properties of HMDSO films produced at the cathode and anode of the reactor at different self-bias voltages. Fourier transform infrared spectroscopy and Raman confocal spectroscopy indicated a significant increase in the content of organic groups when films were deposited at the anode. Analyzing the nanomechanical properties of the cathode and anode films indicated that the penetration depth was higher for samples prepared at the cathode (lower hardness) compared with the samples produced at the anode. The measured contact angles indicated that all samples became hydrophobic with water contact angles close to 100°; however, a different lyophobic character was observed when diiodomethane was used. Films produced at the anode with diiodomethane exhibited higher contact angles than did films produced at the cathode.

Because of the atomic thinness of graphene, its integration into a device will always involve its interaction with at least one supporting substrate, making the surface energy of graphene critical to its real-life applications. In the current paper, the contact angle of graphene synthesized by chemical vapor deposition (CVD) was monitored temporally after synthesis using water, diiodomethane, ethylene glycol, and glycerol. The surface energy was then calculated based on the contact angle data by the Fowkes, Owens-Wendt (extended Fowkes), and Neumann models. The surface energy of fresh CVD graphene grown on a copper substrate (G/Cu) immediately after synthesis was determined to be 62.2 ± 3.1 mJ/m(2) (Fowkes), 53.0 ± 4.3 mJ/m(2) (Owens-Wendt) and 63.8 ± 2.0 mJ/m(2) (Neumann), which decreased to 45.6 ± 3.9, 37.5 ± 2.3, and 57.4 ± 2.1 mJ/m(2), respectively, after 24 h of air exposure. The ellipsometry characterization indicates that the surface energy of G/Cu is affected by airborne hydrocarbon contamination. G/Cu exhibits the highest surface energy immediately after synthesis, and the surface energy decreases after airborne contamination occurs. The root cause of intrinsically mild polarity of G/Cu surface is discussed.

The effect of the modification of poly(lactic acid) (PLA) surface layer using corona treatment in air or nitrogen was evaluated by determination of oxidation degree, contact angle measurements and surface free energy calculations. It was found that as a result of corona discharge the degree of PLA sur- face layer oxidation increases independently of the applied unit activation energy E j as well as the type of atmosphere used. However, the degree of nitriding of the samples modified under nitrogen increases with an increase of E j value and is higher than for the samples modified in air. It was also found that coro- na discharges in both air and nitrogen atmospheres result in the changes in contact angle values of water and diiodomethane on PLA surface layer as well as an increase of surface free energy.

Colloidal solutions of SiO2-TiO2 mixed oxides having different SiO2 contents were synthesized by sol-gel technique and thin films were deposited over glass slides by using dip coating technique. The samples were characterized by XRD, SEM, AFM and methylene blue adsorption methods. The surface free energy of thin films was measured by sessile drop method by using diiodomethane, glycerol and water as probe liquids. The photocatalytic antibacterial activity of the samples was determined for Escherichia coli XL1-blue by using artificial solar irradiation. The surface characterization studies revealed the presence of small crystallites of anatase phase, enhanced dispersion of TiO2 particles and increasing surface free energy at elevated SiO2 content. Highest photocatalytic antibacterial activity was obtained over 92 wt% SiO2 containing sample and strong correlation was found between the bacterial adhesion and antibacterial activity. Surface-adhered E. coli cells having direct contact with TiO2 particles were inactivated at a higher rate than suspended cells. (C) 2014 Elsevier B.V. All rights reserved.

The wetting behavior of diiodomethane on crystalline poly(tetrafluoroethylene) (PTFE), noncrystalline PTFE, and poly(vinylidene cyanide-alt-1H,1H,2H,2H-perfluorodecyl vinyl ether) surfaces are anal...

Fluorine-silicone acrylate copolymers were synthesized with vinyltriethoxysilane (VTES), methyl hexafluorobutyl acrylate (HFMA), and other acrylate monomers by free radical polymerization. Further studies were directed at the water absorption ratio, contact angle and anti-adhesive performance of the films. The results indicated that the copolymers had narrow molecular weight distribution and high temperature stability. The films coated by copolymers showed excellent water/oil repellency with the contact angles of water and diiodomethane of 108.2° and 78.0°, respectively. Anti-adhesive performance testing demonstrated that the films had low peel strength, high residual adhesion rate and excellent water and solvent resistance.

Diamond-like carbon (DLC) and Cr-doped DLC (chromium content 0–18 at.%) layers were deposited by dual pulsed laser ablation. The composition was analyzed using electron probe X-ray microanalysis with wavelength-dispersive spectrometers. Carbon and chromium bonds were determined by X-ray photoelectron spectroscopy. Ethylene glycol, diiodomethane and deionized water were used to measure contact angles and for the calculation of the surface free energy (SFE). Antibacterial properties were studied using gram positive and negative bacteria. The influence of the SFE, hydrophobicity, surface roughness and the zeta potential on antibacterial properties of doped layers was discussed. The relationships between physical and bio-properties are discussed.

The present study utilized a micro-milling facility to fabricate micro dimple textures with extruded center on Ti6Al4V. Geometrical parameters have been varied in order to study the surface properties. The area surface roughness and cross-sectional form of textures were measured by a 3D profilometer. Further, the equilibrium contact angle was measured with ultra-pure water, diiodomethane, and formamide. The surface free energy (SFE) was obtained by three different methods (Owen & Wendt, Wu, and LWAB). The SFE components calculated from LWAB approach sheds more light on the wetting behavior of textured surfaces. Results indicate that the formed textures are defect-free, in good shape and with sharp corners. The area surface roughness, hydrophilicity, and SFE of textured surfaces increases in all geometrical configuration. Further, the surface properties change with the size of the texture. The SFE calculated from all three approaches are in good agreement for each textures configuration. The present study may be helpful to facilitate protein adsorption, cell growth, adhesion, proliferation, and osseointegration rate and to provide insightful information about textured surface properties.

Omniphobic membranes have been brought to great attention recently regarding the ability to resist both water and low surface tension liquids, thus can be utilized for desalination of saline wastewater containing low surface tension contaminants in membrane distillation (MD). In this study, a facile, environment-friendly, and one-step strategy is developed for fabricating an omniphobic membrane with re-entrant structure and low surface energy by spraying a waterborne coating solution comprising of fluorocarbon surfactant (FS, Zonyl@8867L), fluorinated alkyl silane (FAS), and silicon dioxide nano-particles (SiO2 NPs) onto amino functionalized polyvinylidene difluoride (PVDF) membrane via electrostatic adsorption. As a result, the prepared omniphobic FS/FAS/Si membrane possesses high liquid repellency to water, diiodomethane, mineral oil-in-water emulsion (0.10 % v/v), mineral oil, and SDS solution (0.40 mM) with the contact angle of 164.40 ± 0.95°, 159.12 ± 3.12°, 154.31 ± 3.71°, 153.31 ± 2.09°, and 157.14 ± 3.29°, respectively. Compared to the original PVDF membrane, the omniphobic FS/FAS/Si membrane displays higher rejection (about 99.99%) and superior anti-wetting and anti-fouling characteristics even to the saline feed solution with surfactants, oil pollutants, or hydrophilic organic pollutants in MD process. The results mentioned above verify that the obtained omniphobic FS/FAS/Si membrane has potential application for the desalination of the high saline wastewater containing low surface tension contaminants.

This work deals with the determination of several wetting properties (contact angle, surface tension, polarity fraction and spreading parameter) of six novel fatty acid anion-based ionic liquids (FAILs): methyltrioctylammonium hexanoate [N8881][C6:0], methyltrioctylammonium octanoate [N8881][C8:0], methyltrioctylammonium laurate [N8881][C12:0], methyltrioctylammonium palmitate [N8881][C16:0], methyltrioctylammonium stearate [N8881][C18:0] and methyltrioctylammonium oleate [N8881][C18:1]. Surface tension was determined at temperatures from 293 to 333 K, exhibiting a linear decrease within the temperature range. Contact angle measurements were performed on five different surfaces (steel, aluminum, tungsten carbide, cast iron and bronze) using 3 test liquids (water, diiodomethane and ethylenglycol) and each of the synthesized FAILs. Polarity fraction (PF) and the spreading parameter (SP) were calculated in order to gain a deeper understanding of wetting characteristics of these FAILs. Despite the similarity of the obtained results with all FAILs and surfaces, [N8881][C6:0] and [N8881][C8:0] with both cast iron and bronze surfaces were the best surface-FAIL combinations regarding wettability.

Diiodomethane, CH2I2, in a polar solvent undergoes a unique photoinduced reaction whereby I2− and I3− are produced from its photodissociation, unlike for other iodine-containing haloalkanes. While previous studies proposed that homolysis, heterolysis, or solvolysis of iso-CH2I–I, which is a major intermediate of the photodissociation, can account for the formation of I2− and I3−, there has been no consensus on its mechanism and no clue for the reason why those negative ionic species are not observed in the photodissociation of other iodine-containing chemicals in the same polar solvent, for example, CHI3, C2H4I2, C2F4I2, I3−, and I2. Here, using time-resolved X-ray liquidography, we revisit the photodissociation mechanism of CH2I2 in methanol and determine the structures of all transient species and photoproducts involved in its photodissociation and reveal that I2− and I3− are formed via heterolysis of iso-CH2I–I in the photodissociation of CH2I2 in methanol. In addition, we demonstrate that the high polarity of iso-CH2I–I is responsible for the unique photochemistry of CH2I2.

We compare the excited state dynamics of diiodomethane (CH2I2) and bromoiodomethane (CH2BrI) using time resolved photoelectron spectroscopy. A 4.65 eV UV pump pulse launches a dissociative wave packet on excited states of both molecules and the ensuing dynamics are probed via photoionization using a 7.75 eV probe pulse. The resulting photoelectrons are measured with the velocity map imaging technique for each pump-probe delay. Our measurements highlight differences in the dynamics for the two molecules, which are interpreted with high-level ab initio molecular dynamics (trajectory surface hopping) calculations. Our analysis allows us to associate features in the photoelectron spectrum with different portions of the excited state wave packet represented by different trajectories. The excited state dynamics in bromoiodomethane are simple and can be described in terms of direct dissociation along the C–I coordinate, whereas the dynamics in diiodomethane involve internal conversion and motion along multiple dimensions.