Sessile Drop Contact Angle Research Articles

Preserving the reactivity of coatings plasma deposited from oxazoline precursors − An in depth study

Plasma coatings deposited from oxazoline precursors have recently emerged as a valuable utility in many biotechnology application, however, their wider utilization by researchers and industry rely on their long term performance, and more specifically on the retention of their reactivity. Yet, plasma polymers are known to be susceptible to post‐fabrication oxidation processes and intrinsic restructuration. Here, the aging of coatings deposited from oxazoline precursors was studied over 12 months via XPS, ToF‐SIMS, and sessile drop contact angle analysis for samples stored under various conditions. The extent of the damages caused by light and oxygen are identified and explained. Storage away from ambient light and under vacuum proved to retain high reactivity toward COOH‐bearing ligand and biomolecules even 12 months post deposition.

The hydrophobic surface state of talc as influenced by aluminum substitution in the tetrahedral layer

Talc is both an important industrial mineral product recovered by flotation, and also in other cases, a gangue mineral of concern in the flotation of certain sulfide ores, such as the PGM ores from South Africa and from the United States. The talc face surface is naturally hydrophobic with a water sessile drop contact angle of nearly 80°, which accounts for its flotation recovery in one case, and its contamination of sulfide mineral concentrates in other instances. Due to the presence of impurities in the talc structure the surface properties change. One such effect is the presence of aluminum, which can replace silicon in the silica tetrahedral layer of the talc structure. This results in a charge imbalance on the face surface because Si+4 is replaced by Al+3. Sessile drop contact angle and bubble attachment time measurements were made, and these results were compared to the results from molecular dynamics simulations (MDS). The extent of aluminum substitution in the silica tetrahedral layer was considered, and the sessile drop contact angle was found to decrease with increased aluminum content, decreasing from about 80° for no substitution (talc) to 0° for extensive substitution (phlogopite). The water film was found to be stable at the surface of highly aluminum substituted crystals due to the interaction between water molecules and the increased polarity of the surface state. This stable water film restricts the air bubble from attaching to such face surfaces. However, in the absence of aluminum substitution, no interactions between the water molecules and the face surface were observed and the air bubble readily attached to the face surface. This study provides additional understanding of how aluminum substitution in the tetrahedral layer affects the fundamental surface properties of talc, paving the way for the design of improved reagents for talc flotation as an industrial mineral product, and for talc depression in the recovery of sulfide mineral concentrates.

A new approach to determine the relative importance of DLVO and non-DLVO colloid retention mechanisms in porous media

The DLVO (Derjaguin-Landau-Verwey-Overbeek) approach to predict colloid mobility in porous media is centered on solution ionic strength and physicochemical surface properties of colloids and solid matrix. However, several colloid retention mechanisms are not related to such interfacial properties, but instead to hydraulic features like flow regime and pore structure. We aimed to determine the relative importance of DLVO-related and non-DLVO-related retention mechanisms, which remains poorly understood. For that, we developed a conceptual approach based on previous research on organic matter-coated goethite (OMCG) colloid mobility in quartz sand. OMCG colloid retention by DLVO mechanisms was negligible at 0.0 mM ionic strength. Therefore, any retention at 0.0 mM can be assigned to non-DLVO retention. At increasing ionic strength, the amount of DLVO retention is rising, while the amount of non-DLVO retention is independent from ionic strength and thus remains constant. This allows for a differentiation between the two types of retention mechanisms. To test this conceptual approach, we conducted OMCG colloid breakthrough experiments at varying interfacial conditions (ionic strength: 0.0–5.53 mM) and hydraulic conditions (flow rate: 0.11 – 5.02 cm min−1). From sessile drop contact angles and zeta potentials, DLVO and extended DLVO (XDLVO) interactions including Lewis acid-base interactions were approximated. The results show that colloid retention was almost exclusively related to DLVO retention mechanisms, while retention by hydraulic factors was practically irrelevant. We conclude that our conceptual approach can be applied to determine the relative importance of colloid retention caused by DLVO and non-DLVO mechanisms for further colloid-solid matrix systems.

Natural colloid mobilization and leaching in wettable and water repellent soil under saturated condition

AbstractThe coupled transport of pollutants that are adsorbed to colloidal particles has always been a major topic for environmental sciences due to many unfavorable effects on soils and groundwater. This laboratory column study was conducted under saturated moisture conditions to compare the hydrophobic character of the suspended and mobilized colloids in the percolates released from a wettable subsoil and a water repellent topsoil. Both soils with different organic matter content were analyzed for wettability changes before and after leaching using sessile drop contact angles as well as water and ethanol sorptivity curves, summarized as repellency index. Hydrophobicity of the effluent suspensions was assessed using the C18 adsorption method. Water repellency level of the repellent soil decreased after leaching but remained on a lower level of water repellency, while, the wettable soil remained wettable. The leached colloids from the repellent soil were predominantly hydrophilic and the percentage of the hydrophobic colloid fraction in the effluent did not systematically changed with time. Total colloid release depended on soil carbon stock but not on soil wettability. Our results suggest that due to the respective character of transported colloids a similar co-transport mechanism for pollutants may occur which does not depend explicitly on soil wettability of the releasing horizon, but could be more affected by total SOM content. Further studies with a wider range of soils are necessary to determine if the dominant hydrophilic character of leached colloids is typical. Due to the mostly hydrophilic colloid character we conclude also that changes in wettability status, i.e. of wettable subsoil horizons due to the leachate, may not necessarily occur very fast, even when the overlaying topsoil is a repellent soil horizon with a high organic matter content.

Wettability control of PET surface by plasma-induced polymer film deposition and plasma/UV oxidation in ambient air

The surface modification of poly (ethylene terephthalate) (PET) film was achieved by two sequential atmospheric pressure plasma jet (APPJ) treatments: plasma-induced polymer coating with hexamethyldisiloxane (HMDSO) and plasma oxidation with nitrogen gas. For comparison with APPJ-oxidation, oxidation by excimer ultra violet (UV) light irradiation was performed. The sessile drop and Wilhelmy contact angle measurements revealed that the PET film subjected to APPJ-coating showed superior water repellency and subsequent APPJ- or UV-oxidation made the PET film super-hydrophilic. UV-oxidation was also performed on the PET film treated by APPJ-coating, covered by a metal mesh. The difference in the contact angles between the surface areas covered with and without the metal strip mask was evident based on the Wilhelmy contact angle measurement. Both hydrophobic and hydrophilic surfaces did not exhibit contact angle hysteresis and had excellent stability of wettability. Furthermore, the hydrophilic surface treated only by APPJ- or UV-oxidation exhibited contact angle hysteresis and hydrophobic recovery with prolonged storage. Field emission scanning electron microscopy (FE-SEM) and SEM observation revealed that the morphology of the PET surface became granular after APPJ-coating. From the analyses of X-ray photoelectron spectroscopy (XPS) and grazing-angle attenuated total reflectance Fourier transform infrared (GATR-FTIR) spectroscopy, the APPJ-coated film composed mainly of inorganic SiO2 with traces of carbon derived from CH3 group, which makes the coating surface more hydrophobic. The subsequent oxidation process of APPJ or UV light leads to the decomposition of the methyl group at the surface. The antifouling properties of the PET surface against soil particulates deposited from air and their removal in aqueous detergent solution, were improved by APPJ-coating and subsequent APPJ-oxidation, respectively.

Assessment of physical properties of self-bonded composites made of cellulose nanofibrils and poly(lactic acid) microfibrils

Cellulose nanofibrils and poly(lactic acid) microfibrils, two bio-based polymers were used to elaborate composite films, and their properties were evaluated. Cellulose nanofibrils were obtained from organic pulping with total chlorine-free bleaching and were manufactured using high-pressure homogenization; while poly(lactic acid) microfibrils were obtained from a commercial partner. Morphological aspects of cellulose nanofibrils were assessed by atomic force microscopy showing traditional morphology for the elaborated nanofibrils, as well as the effects of sonication on the poly(lactic acid) microfibrils. Self-bonded composite films with different compositions were fabricated by hot pressing following methodologies previously reported. Uniaxial tensile stress was measured with a universal testing machine showing a decrease in most mechanical properties because of the low interactions between cellulose nanofibrils and polylactide microfibrils. Water vapor permeability was evaluated with a thermohygrometer and surface energy with the sessile-drop contact angle method these results showed good values for printing and gluing, with surface free energies ranging between 27 and 60 m Nm−1. Furthermore, industrial standards for paper-like materials and thermal properties of the composites were also analyzed of which it is to highlight the good bending strength as well as the concurrence of the results of Parker Print Surface tests with those of water contact angle.

On the equilibrium contact angle of sessile liquid drops from molecular dynamics simulations.

We present a new methodology to estimate the contact angles of sessile drops from molecular simulations by using the Gaussian convolution method of Willard and Chandler [J. Phys. Chem. B 114, 1954-1958 (2010)] to calculate the coarse-grained density from atomic coordinates. The iso-density contour with average coarse-grained density value equal to half of the bulk liquid density is identified as the average liquid-vapor (LV) interface. Angles between the unit normal vectors to the average LV interface and unit normal vector to the solid surface, as a function of the distance normal to the solid surface, are calculated. The cosines of these angles are extrapolated to the three-phase contact line to estimate the sessile drop contact angle. The proposed methodology, which is relatively easy to implement, is systematically applied to three systems: (i) a Lennard-Jones (LJ) drop on a featureless LJ 9-3 surface; (ii) an SPC/E water drop on a featureless LJ 9-3 surface; and (iii) an SPC/E water drop on a graphite surface. The sessile drop contact angles estimated with our methodology for the first two systems are shown to be in good agreement with the angles predicted from Young's equation. The interfacial tensions required for this equation are computed by employing the test-area perturbation method for the corresponding planar interfaces. Our findings suggest that the widely adopted spherical-cap approximation should be used with caution, as it could take a long time for a sessile drop to relax to a spherical shape, of the order of 100 ns, especially for water molecules initiated in a lattice configuration on a solid surface. But even though a water drop can take a long time to reach the spherical shape, we find that the contact angle is well established much faster and the drop evolves toward the spherical shape following a constant-contact-angle relaxation dynamics. Making use of this observation, our methodology allows a good estimation of the sessile drop contact angle values even for moderate system sizes (with, e.g., 4000 molecules), without the need for long simulation times to reach the spherical shape.

Correction to "Contact Angle of Sessile Drops in Lennard-Jones Systems".

ADVERTISEMENT RETURN TO ISSUEPREVAddition/CorrectionNEXTORIGINAL ARTICLEThis notice is a correctionCorrection to “Contact Angle of Sessile Drops in Lennard-Jones Systems”Michaela HeierMichaela HeierMore by Michaela Heier, Stefan BeckerStefan BeckerMore by Stefan Beckerhttp://orcid.org/0000-0002-4460-9497, Herbert M. UrbassekHerbert M. UrbassekMore by Herbert M. Urbassekhttp://orcid.org/0000-0002-7739-4453, Martin HorschMartin HorschMore by Martin Horsch, and Hans Hasse*Hans HasseMore by Hans HasseCite this: Langmuir 2018, 34, 10, 3374Publication Date (Web):March 1, 2018Publication History Published online1 March 2018Published inissue 13 March 2018https://doi.org/10.1021/acs.langmuir.8b00609Copyright © 2018 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views608Altmetric-Citations2LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (201 KB) Get e-Alerts Get e-Alerts

Variability in Microplate Surface Properties and Its Impact on ELISA.

Microplate-based immunoassays are widely used in clinical and research settings to measure a broad range of biomarkers present in complex matrices. Assay variability within and between microplates can give rise to false-negative and false-positive results leading to incorrect conclusions. To date, the contribution of microplates to this variability remains poorly characterized and described. This study provides new insights into variability in immunoassays attributable to surface characteristics of commercial microplates. Well-to-well assay variation in γ-treated and nontreated 96-well opaque microplates suitable for chemiluminescence assays was determined by use of a validated sandwich ELISA. Microplate surface characteristics were assessed by sessile drop contact angle measurements, scanning electron microscopy, energy dispersive x-ray spectroscopy, and atomic force microscopy. All microplate types tested exhibited vendor-specific assay response profiles; and "rogue" plates with very high intraassay variation and deviant mean assay responses were found. Within-plate, location-dependent bias in assay responses and variability in well contact angle were also observed. We demonstrate substantial differences in well-surface properties with putative effects on protein-coating reproducibility and hence consistency in immunoassay responses. A surface "cleaning" effect on manufacturing residues was attributed to γ-irradiation, and treated microplates manifest increased polar functionalities, surface roughness, and assay responses. Our data suggest that tighter control of variability in surface roughness, wettability, chemistry, and level of residual contaminants during microplate preparation is warranted to improve consistency of ELISA assay read out.

Contact angle control of sessile drops on a tensioned web

In this study, the influence of the change of tension applied to flexible and thin web substrate on the contact angle of sessile drop in roll-to-roll system was investigated. Graphene oxide and deionized water solutions were used in the experiments. Tension was changed to 29, 49, and 69 N, and the casting distance of the micropipette and the material was set to 10, 20, and 40 mm, and the droplet volume was set to 10, 20, and 30 μL, respectively. Statistical analysis of three variables and analysis of the variance methodology showed that the casting distance was most significant for the contact angle change, and the most interesting tension variable was also affected. The change in tension caused the maximum contact angle to change by 5.5°. The tension was not uniform in the width direction. When the droplet was applied in the same direction in the width direction, it was confirmed that the tension unevenness had great influence on the contact angle up to 11°. Finally, the casting distance, which has a large effect on the contact angle, was calibrated in the width direction to reduce the width direction contact angle deviation to 1%. This study can be applied to fine patterning research using continuous inkjet printing and aerosol jet printing, which are roll-to-roll processes based on droplet handling.

Effects of organic matter coatings on the mobility of goethite colloids in model sand and undisturbed soil

SummaryThe mobility of goethite (OMCG) colloids coated with organic matter was studied in goethite‐coated quartz sand and in undisturbed subsoil rich in natural coatings of iron oxide. Classic Derjaguin–Landau–Verwey–Overbeek (DLVO) interactions and DLVO extended by Lewis acid–base parameters (XDLVO) were estimated between colloids and goethite‐coated sand from zeta potentials and sessile drop contact angles. The OMCG colloids were retained completely in goethite‐coated sand, whereas preconditioning of the solid matrix with dissolved organic matter (DOM) enabled subsequent colloid transport. Zeta potential values showed that goethite‐coated sand was modified strongly by DOM preconditioning. The DLVO and XDLVO interactions were estimated for the pairs of OMCG colloids and for (i) quartz, (ii) goethite and (iii) organic matter‐coated goethite. Both DLVO approaches were able to predict general trends of colloid breakthrough. An exception was the XDLVO interaction for combination (iii), which showed short‐distance (<1.3 nm) repulsive interactions that were inconsistent with breakthrough behaviour. Analogous to OMCG colloid transport in the sand, DOM preconditioning was also the prerequisite for OMCG colloid transport in undisturbed subsoil. Total colloid breakthrough in the soil was less than in the sand, probably because of straining in pore throats and retention at air–water interfaces. We concluded that the DLVO and XDLVO approaches were in general capable of predicting trends of OMCG colloid mobility in goethite‐coated sand. We concluded further that the basic principles of OMCG colloid transport were transferrable from the simplified model system to the more complex natural system despite considerable differences in surface properties, pore structure and water content.Highlights How will organic matter (OM) coatings on the solid matrix affect mobility of iron oxide colloids? Effect of OM on mobility was assessed in simple model soil systems and in undisturbed soil. OM coatings modify properties of the solid matrix surface and are a prerequisite for colloid transport. Balances between OM transport, coating formation and decomposition control colloid mobility.

An improved sessile drop method for assessing the wettability of heterogeneous coal surface

ABSTRACTTo assess the wettability of heterogeneous coal surface, a new modified sessile drop technique named volume–length method is proposed to calculate the contact angle according to the spreading ability of droplet on the coal surface. The tested contact angles were compared with the predicted contact angles using Cassie–Baxter model. Low ash coal and kaoline powders are mixed with different mass ratios and mixing degrees. The mixtures were pressed to plates for sessile drop contact angle tests. The surface chemical component and nonuniform degree determine the droplet spreading on the coal surface, thereby affecting the contact angle.

Biofilm formation and multidrug-resistant Aeromonas spp. from wild animals.

The 'One Health' concept recognises that the health of humans, animals and the environment are interconnected. Therefore, knowledge on the behaviour of micro-organisms from the most diverse environmental niches is important to prevent the emergence and dissemination of antimicrobial resistance. Wild animals are known to carry antimicrobial-resistant micro-organisms with potential public health impact. However, no data are available on the behaviour of sessile bacteria from wild animals, although antimicrobial resistance is amplified in biofilms. This study characterised the ciprofloxacin susceptibility and the adhesion and biofilm formation abilities of 14 distinct Aeromonas spp. (8 Aeromonas salmonicida, 3 Aeromonas eucrenophila, 2 Aeromonas bestiarum and 1 Aeromonas veronii) isolated from wild animals and already characterised as resistant to β-lactam antibiotics. The ciprofloxacin MIC was determined according to CLSI guidelines. A biofilm formation assay was performed by a modified microtitre plate method. Bacterial surface hydrophobicity was assessed by sessile drop contact angle measurement. All Aeromonas spp. strains were resistant to ciprofloxacin (MICs of 6-60μg/mL) and had hydrophilic surfaces (range 2-37mJ/m2). These strains were able to adhere and form biofilms with distinct magnitudes. Biofilm exposure to 10×MIC of ciprofloxacin only caused low to moderate biofilm removal. This study shows that the strains tested are of potential public health concern and emphasises that wild animals are potential reservoirs of multidrug-resistant strains. In fact, Aeromonas spp. are consistently considered opportunistic pathogens. Moreover, bacterial ability to form biofilms increases antimicrobial resistance and the propensity to cause persistent infections.

Organosilane Chemical Gradients: Progress, Properties, and Promise.

Chemical gradients play an important role in nature, driving many different phenomena critical to life, including the transport of chemical species across membranes and the transport, attachment, and assembly of cells. Taking a cue from these natural processes, scientists and engineers are now working to develop synthetic chemical gradients for use in a broad range of applications, such as in high-throughput investigations of surface properties, as means to guide the motions and/or assembly of liquid droplets, vesicles, nanoparticles, and cells and as new media for stationary-phase-gradient chemical separations. Our groups have been working to develop new methods for preparing chemical gradients from organoalkoxysilane and organochlorosilane precursors and to obtain a better understanding of their properties on macroscopic to microscopic length scales. This review highlights our recent work on the development of controlled-rate infusion and infusion-withdrawal dip-coating methods for the preparation of gradients on planar glass and silicon substrates, on thin-layer chromatography plates, and in capillaries and monoliths for liquid chromatography. We also cover the new knowledge gained from the characterization of our gradients using sessile drop and Wilhelmy plate dynamic water contact angle measurements, X-ray photoelectron spectroscopy mapping, and single-molecule tracking and spectroscopy. Our studies reveal important evidence of phase separation and cooperative interactions occurring along multicomponent gradients. Emerging concepts and new directions in the preparation and characterization of organosilane-based chemical gradients are also discussed.

Wettability and bonding quality of exterior coatings on jabon and sengon wood surfaces

Wettability and bonding quality of exterior coatings on fast-growing wood surfaces were studied. Samples of air-dried flat-grained (tangential surface) and edge-grained (radial surface) pattern of jabon (Anthocephalus cadamba) and sengon (Paraserianthes falcataria) woods were used. Before application of exterior coatings, the surfaces of the lumber samples were sanded. To provide wood surfaces with various degrees of roughness, abrasive papers of 120, 240, and 360 grits were used for the surface preparation. The wettability of two exterior coatings (water-based acrylic and oil-based alkyd varnishes) on the sanded wood surfaces was measured using a sessile drop contact angle method. The Shi and Gardner (S/G) model was used to evaluate and compare the wettability of the surface coatings on the wood. The sanded wood samples were coated with the two coatings (two layers each). Bonding quality of the coating layers was measured using a crosscut tape test method. Experimental results show that constant contact angle change rate (K value) of the S/G model decreased as the grit number of abrasive paper increased. This indicates that the wettability decreased as the roughness of the surface decreased (surface becomes smoother). There was no evidence of differences in wettability between tangential and radial wood surfaces. The oil-based alkyd coating generated better wettability compared to the water-based acrylic. The crosscut tests showed that the bonding quality of the coating films on both jabon and sengon wood decreased as the surface became smoother. The sengon wood compared to jabon wood provided better coating wettability and bonding quality. Wettability in terms of the K values was a good indication for determining the bonding quality of the two varnish layers.

Enhanced Osseointegration of Porous Titanium Modified with Zeolitic Imidazolate Framework-8.

Nanoscale zeolitic imidazolate framework-8 (ZIF-8)-modified titanium (ZIF-8@AHT) can enhance osteogenesis in vitro. In this study, we systematically and quantitatively examined the effects of ZIF-8@AHT on osteogenesis, and investigated its ability to form bone in vivo. First, we coated various quantities of nanoscale ZIF-8 crystals on alkali- and heat-treated titanium (AHT) by controlling the concentration of the synthesis solution. We then characterized the ZIF-8@AHT materials using scanning electron microscopy (SEM), powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and determination of the sessile drop contact angle. To illustrate the combined effects of micro/nanotopography and ZIF-8@AHT composition on bone regeneration, we cultured MC3T3-E1 preosteoblast cells on various titanium substrates in vitro by setting pure titanium (Ti) and AHT as control groups. The ZIF-8@AHTs enhanced cell bioactivity compared with AHT and Ti, as evidenced by increased extracellular matrix (ECM) mineralization, collagen secretion and the upregulated expression of osteogenic genes (Alp, Col1, Opg, and Runx2) and osteogenesis-related proteins (ALP and OPG). ZIF-8@AHT-1/8 exhibited better osteogenic activity compared with the other ZIF-8@AHT groups investigated. We subsequently inserted Ti, AHT, and ZIF-8@AHT-1/8 implants into the healed first molars (M1s) of mice, and found that ZIF-8@AHT-1/8 also promoted osseointegration at the bone-implant interface. These results suggest that ZIF-8@AHT-1/8 has great potential for practical application in implant modification.

Design and Characterization of Biocomposites from Poly(lactic acid) (PLA) and Buriti Petiole (Mauritia flexuosa)

Buriti or miriti (Mauritia flexuosa) is a palm tree found in the Brazilian cerrado. Herein buriti petiole, part of the trunk that supports the leaves, was ground and used without any treatment as low density load to prepare poly(lactic acid) biocomposites. X-ray microtomography of buriti petiole showed its porous structure, with a wide pore size distribution determined with the aid of SEM. The obtained biocomposites with 1, 5 and 10 wt% of buriti petiole particles were investigated by their sessile drop contact angle, FTIR, TGA and tensile test. The tensile properties indicated poor adhesion between phases, which is crucial to optimize the biocomposite’s performance. Further studies with fiber treatment are being planned.

Effect of dimethyl sulfoxide on dentin collagen

ObjectivesInfiltration of adhesive on dentin matrix depends on interaction of surface and adhesive. Interaction depends on dentin wettability, which can be enhanced either by increasing dentin surface energy or lowering the surface energy of adhesive. The objective was to examine the effect of dimethyl sulfoxide (DMSO) on demineralized dentin wettability and dentin organic matrix expansion. MethodsAcid-etched human dentin was used for sessile drop contact angle measurement to test surface wetting on 1–5% DMSO-treated demineralized dentin surface, and linear variable differential transformer (LVDT) to measure expansion/shrinkage of dentinal matrix. DMSO-water binary liquids were examined for surface tension changes through concentrations from 0 to 100% DMSO. Kruskal–Wallis and Mann–Whitney tests were used to test the differences in dentin wettability, expansion and shrinkage, and Spearman test to test the correlation between DMSO concentration and water surface tension. The level of significance was p<0.05. ResultsPretreatment with 1–5% DMSO caused statistically significant concentration-dependent increase in wetting: the immediate contact angles decreased by 11.8% and 46.6% and 60s contact angles by 9.5% and 47.4% with 1% and 5% DMSO, respectively. DMSO-water mixtures concentration-dependently expanded demineralized dentin samples less than pure water, except with high (≥80%) DMSO concentrations which expanded demineralized dentin more than water. Drying times of LVDT samples increased significantly with the use of DMSO. SignificanceIncreased dentin wettability may explain the previously demonstrated increase in adhesive penetration with DMSO-treated dentin, and together with the expansion of collagen matrix after drying may also explain previously observed increase in dentin adhesive bonding.

Coaxially electrospun super-amphiphobic silica-based membrane for anti-surfactant-wetting membrane distillation

Membrane distillation (MD) is a promising desalination technology that is capable of utilizing low-grade thermal energy to treat highly saline feed water. Conventional hydrophobic MD membranes limit the application of MD to desalination of relatively clean water without amphiphilic contaminants, as those amphiphilic constituents promote wetting of MD membrane and failure of the MD process. Here, we report a facile approach to fabricate superamphiphobic MD membranes with anti-surfactant-wetting property based on coaxial electrospinning. Silica nanoparticles were used as the sheath solution to create electrospun fibers with nanoscale roughness on individual fibers. After surface fluorination, the fabricated membrane exhibited superamphiphobicity as reflected by very high sessile drop contact angles with both water and oil. Robust MD performance in the presence of surfactants was observed with the superamphiphobic membrane, but not with commercial hydrophobic membranes or amphiphobic membrane without local nanoscale roughness.

Bonding of densified beech wood using adhesives based on thermally modified soy proteins

The bondability/glueability of aged and sanded thermo-hydro-mechanically (THM) densified beech wood (Fagus sylvatica L.) was tested and compared with undensified sanded beech wood as a control. THM and control specimens were bonded with five different soy protein isolate (SPI) based adhesives. Commercial SPI powder was thermally modified in the vacuum chamber at 50 or 100 °C and pH adjusted (to pH 10.0) dispersions in water prepared at 24, 50 or 90 °C. Wettability was determined with measuring the sessile drop contact angles of water. Effective penetrations (EPs) and tensile shear strengths of THM and control specimens were determined. THM and control wood had similar wettability. Although THM wood had lower moisture content than control wood, it absorbed the water more slowly than control wood. THM specimens showed lower EPs than control specimens when comparing individual adhesives due to increased density of THM wood. Adhesives prepared with SPI thermally modified at 50 °C showed statistically significantly lower tensile shear strength of bonded THM specimens than that of bonded control specimens. THM densification had no significant effect on the bonding strengths of adhesives prepared with non-modified SPI and SPI thermally modified at 100 °C.