scholarly journals Effect of Surface Properties on the Photo-Induced Crawling Motion of Azobenzene Crystals on Glass Surfaces

2021 ◽  
Vol 9 ◽  
Author(s):  
Yasuo Norikane ◽  
Masaru Hayashino ◽  
Mio Ohnuma ◽  
Koji Abe ◽  
Yoshihiro Kikkawa ◽  
...  
Keyword(s):  
Surface Properties ◽  
Shape Change ◽  
Contact Angles ◽  
Light Sources ◽  
Water Contact ◽  
Penetration Length ◽  
Glass Substrates ◽  
Directional Motion ◽  
Surface Modified ◽  
Glass Surfaces

Photo-induced crawling motion of a crystal of 3,3′-dimethylazobenzene (DMAB) on a glass substrate having different surface properties was studied. When exposed to UV and visible lights simultaneously from different directions, crystals crawl continuously on a glass surface. On a hydrophilic surface, the crystals crawled faster than those on other surfaces but crystals showed spreading while they moved. On hydrophobic surfaces, on the other hand, the crystals showed little shape change and slower crawling motion. The contact angles of the liquid phase of DMAB on surface-modified glass substrates showed positive correlation with the water contact angles. The interaction of melted azobenzene with glass surfaces plays an important role for the crawling motion. We proposed models to explain the asymmetric condition that leads to the directional motion. Specifically by considering the penetration length of UV and visible light sources, it was successfully shown that the depth of light penetration is different at the position of a crystal. This creates a nonequilibrium condition where melting and crystallization are predominant in the same crystal.

Surface Modification of PEOT/PBT Membrane with Silk Fibroin Anchoring and its Potential Application in Artificial Salivary Gland Construct

2012 ◽  
Vol 538-541 ◽  
pp. 52-59
Author(s):  
Jie Zhu ◽  
Ming Shi Li ◽  
Li Qun Wang ◽  
Xiao Lin Zhu
Keyword(s):  
Salivary Gland ◽  
Silk Fibroin ◽  
Potential Application ◽  
Contact Angles ◽  
Water Contact ◽  
Polar Groups ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Surface Modified

We reported the preparation of surface modified poly (ethylene oxide terephthalate) - poly (butylene terephthalate) membrane by the method of silk fibroin anchoring, namely SF/(PEOT/PBT). Its surface properties were characterized by contact angles and XPS and the biocompatibility of the composite membrane was further evaluated by human salivary epithelial cells (HSG cells) growth in vitro. Results revealed that SF/(PEOT/PBT) possessed the low water contact angle (48.0±3.0°) and immobilized a great amount of fibroin (fibroin surface coverage: 26.39 wt%), which attributed to the formation of polar groups such as hydrosulfide group, sulfonic group, carboxyl and carbonyl ones in the process of SO2 plasma treatment. HSG cells growth in vitro indicated that the silk fibroin anchoring could significantly enhance the biocompatibility of PEOT/PBT membrane, which suggested the potential application of fibroin anchoring PEOT/PBT for clinical HSG cells transplantation in the artificial salivary gland construct.

scholarly journals Surface Properties of Pine Scrimber Panels with Varying Density

Coatings ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 397 ◽  
Author(s):  
Jinguang Wei ◽  
Qiuqin Lin ◽  
Yahui Zhang ◽  
Wenji Yu ◽  
Chung-Yun Hse ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Surface Properties ◽  
Photoelectron Spectroscopy ◽  
Lower Surface ◽  
Contact Angles ◽  
High Density ◽  
Water Contact ◽  
Change Rate ◽  
Hydrophilic Material ◽  
Wood Grain

Coating quality for scrimber products against exterior conditions is largely dependent on the surface properties. The wettability, morphology, and chemical composition of pine scrimber surfaces were investigated to better understand the surface properties. The scrimber was found to be a hydrophilic material because the water contact angles were less than 90°. The panels with a density of 1.20 g/cm3 had the largest angle change rate (k = 0.212). As the panel density increased, the instantaneous contact angle of each test liquid (i.e., water, formamide, and diiodomethane) on the panels decreased, and so did surface free energy. Panels with higher density showed lower surface roughness. Surface roughness across the wood grain was greater than that along the grain. SEM observations showed the high-density panels had a smoother surface with fewer irregular grooves in comparison with the low-density panels. X-ray photoelectron spectroscopy (XPS) analysis indicated that more unoxygenated groups appeared on the surface of high-density panels.

Diamond-Like Carbon Films for Silicon Passivation in Microelectromechanical Devices

1995 ◽  
Vol 383 ◽  
Author(s):  
M. R. Houston ◽  
R. T. Howe ◽  
K Komvopoulos ◽  
R. Maboudian
Keyword(s):  
Contact Angle ◽  
Surface Properties ◽  
Photoelectron Spectroscopy ◽  
Microelectromechanical Systems ◽  
Adhesion Force ◽  
Contact Angles ◽  
Vacuum Arc ◽  
Diamond Like Carbon ◽  
Adhesion Forces ◽  
Water Contact

ABSTRACTThe surface properties of diamond-like carbon (DLC) films deposited by a vacuum arc technique on smooth silicon wafers are presented with specific emphasis given to stiction reduction in microelectromechanical systems (MEMS). The low deposition temperatures afforded by the vacuum arc technique should allow for easy integration of the DLC films into the current fabrication process of typical surface micromachines by means of a standard lift-off processing technique. Using X-ray photoelectron spectroscopy (XPS), contact angle analysis, and atomic force microscopy (AFM), the surface chemistry, microroughness, hydrophobicity, and adhesion forces of DLC-coated Si(100) surfaces were measured and correlated to the measured water contact angles. DLC films were found to be extremely smooth and possess a water contact angle of 87°, which roughly corresponds to a surface energy of 22 mJ/m2. It is shown that the pull-off forces measured by AFM correlate well with the predicted capillary forces. Pull-off forces are reduced on DLC surfaces by about a factor of five compared to 10 nN pull-off forces measured on the RCA-cleaned silicon surfaces. In the absence of meniscus forces, the overall adhesion force is expected to decrease by over an order of magnitude to the van der Waals attractive force present between two DLC-coated surfaces- To further improve the surface properties of DLC, films were exposed to a fluorine plasma which increased the contact angle to 99° and lowered the pull-off force by approximately 20% over that obtained with as-deposited DLC. The significance of these results is discussed with respect to stiction reduction in micromachines.

scholarly journals Adhesion to Bile Drain Materials and Physicochemical Surface Properties of Enterococcus faecalis Strains Grown in the Presence of Bile

2002 ◽  
Vol 68 (8) ◽  
pp. 3855-3858 ◽  
Author(s):  
Karola Waar ◽  
Henny C. van der Mei ◽  
Hermie J. M. Harmsen ◽  
John E. Degener ◽  
Henk J. Busscher
Keyword(s):  
Surface Properties ◽  
Enterococcus Faecalis ◽  
Photoelectron Spectroscopy ◽  
Surface Protein ◽  
Lower Surface ◽  
Contact Angles ◽  
Surface Proteins ◽  
Water Contact ◽  
Zeta Potentials ◽  
Aggregation Substance

ABSTRACT The aim of this study is to determine whether growth in the presence of bile influences the surface properties and adhesion to hydrophobic bile drain materials of Enterococcus faecalis strains expressing aggregation substance (Agg) or enterococcal surface protein (Esp), two surface proteins that are associated with infections. After growth in the presence of bile, the strains were generally more hydrophobic by water contact angles and the zeta potentials were more negative than when the strains were grown in the absence of bile. Nitrogen was found in lower surface concentrations upon growth in the presence of bile, whereas higher surface concentrations of oxygen were measured by X-ray photoelectron spectroscopy. Moreover, an up to twofold-higher number of bacteria adhered after growth in bile for E. faecalis not expressing Agg or Esp and E. faecalis with Esp on its surface. E. faecalis expressing Agg did not adhere in higher numbers after growth in bile, possibly because they mainly adhere through positive cooperativity and less through direct interactions with a substratum surface. Since adhesion of bacteria is the first step in biomaterial-centered infection, it can be concluded that growth in bile increases the virulence of E. faecalis.

Supramolecular functionalized polybenzoxazines from azobenzene carboxylic acid/azobenzene pyridine complexes: synthesis, surface properties, and specific interactions

RSC Advances ◽  
2015 ◽  
Vol 5 (17) ◽  
pp. 12763-12772 ◽  
Author(s):  
Mohamed Gamal Mohamed ◽  
Chi-Hui Hsiao ◽  
Kuo-Chih Hsu ◽  
Fang-Hsien Lu ◽  
His-Kang Shih ◽  
...  
Keyword(s):  
Carboxylic Acid ◽  
Surface Properties ◽  
High Water ◽  
Contact Angles ◽  
Supramolecular Complex ◽  
Specific Interactions ◽  
Water Contact ◽  
Pyridine Complexes

Supramolecular complex of azobenzene carboxylic acid/pyridine functionalized benzoxazine system featured significantly lower curing temperatures and maintain high water contact angles.

scholarly journals The Direct Cause of Amplified Wettability: Roughness or Surface Chemistry?

2021 ◽  
Vol 5 (8) ◽  
pp. 213
Author(s):  
Emmanuel E. Ubuo ◽  
Inimfon A. Udoetok ◽  
Andrew T. Tyowua ◽  
Ifiok O. Ekwere ◽  
Hamza S. Al-Shehri
Keyword(s):  
Surface Chemistry ◽  
Solid Material ◽  
Contact Angles ◽  
Gradual Change ◽  
Water Contact ◽  
Drop Shape ◽  
Angle Measurements ◽  
Contact Angle Measurements ◽  
Analysis System ◽  
Glass Surfaces

Higher contact angles or amplified wettability observed on surfaces of rough solid materials are typically expressed as a function of a physical dimension (roughness factor). Herein, we present a simple experimental approach that demonstrates that roughness may only magnify the inherent surface chemistry that seems to have direct influence on surface wettability. We investigate gradual change in surface chemistry (hydrophobisation) of rough and smooth glass surfaces, from a very low concentration (10−7 M) of dichlorodimethylsilane, DCDMS through various intermediate hydrophilic/hydrophobic states to when the surfaces are maximally hydrophobised with DCDMS at 0.1 M. The wettability of the modified glasses was studied by water contact angle measurements using drop shape analysis system (DSA). The data obtained indicate a deviation from Wenzel model, with the functionalized rough glass surfaces showing higher reactivity towards DCDMS when compared to the smooth glass surfaces, indicating that the two surfaces are not chemically identical. Our study reveals that just like transforming a solid material to powder, a well-divided glass (rough) surface may not only exhibit a greater surface area than the smooth counterpart as rightly predicted by the Wenzel model, but seems to be bloated with functional groups (–OH or –CH3) that can amplify surface interaction when such functional species dominate the solid surface.

The Wetting of Insect Cuticles by Water

1955 ◽  
Vol 32 (3) ◽  
pp. 591-617 ◽  
Author(s):  
M. W. HOLDGATE
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Surface Properties ◽  
Surface Composition ◽  
Contact Angles ◽  
Aquatic Species ◽  
Water Contact ◽  
Calliphora Erythrocephala ◽  
Wetting Properties ◽  
Wide Range

1. The water contact angles of insects show a wide range of variation, which is broadly correlated with surface roughness and with habitat. 2. The contact angles of species inhabiting stored products or carrion are greatly modified by contamination. This produces large variations between apparently similar individuals. 3. In terrestrial insects surface roughness increases the contact angles to very large apparent values. Detailed analyses of its effect have been made in the pupa of Tenebrio molitor and the adult Calliphora erythrocephala. In some aquatic insects surface roughness leads to a reduction in the contact angles; this has been studied in the nymph of Anax imperator. 4. Prolonged immersion in water causes a lowering of the contact angles of all the insects examined, and the low angles of many aquatic species may therefore be the direct effect of their environment. In some aquatic species there is evidence of the active maintenance of a large contact angle during life. 5. Changes in contact angle accompany processes of cuticle secretion and will occur at any moult if changes in roughness or habitat take place. 6. The observed variations of surface properties can be explained without assuming any variation in the chemical composition of the cuticle surface. Wetting properties are of little value as indicators of cuticle surface composition. 7. The biological aspects of insect surface properties are briefly discussed.

Influence of atmospheric pressure plasma treatments on the surface properties of ligno-cellulosic substrates

Holzforschung ◽  
2016 ◽  
Vol 70 (1) ◽  
pp. 55-61 ◽  
Author(s):  
William P. Lekobou ◽  
Karl R. Englund ◽  
Marie-Pierre Laborie ◽  
Patrick D. Pedrow
Keyword(s):  
Surface Properties ◽  
Atmospheric Pressure ◽  
Wood Flour ◽  
Capillary Rise ◽  
Treated Wood ◽  
Atmospheric Pressure Plasma ◽  
Contact Angles ◽  
Water Contact ◽  
Weakly Ionized ◽  
Metallic Mesh

AbstractThe paper aims at the investigation of atmospheric pressure weakly ionized plasmas with argon and acetylene to deposit plasma-polymerized coatings on wood veneers (birch, maple), cellulose paper, and pine wood flour to modify their surface properties, in particular their topography and wettability. The treatment was performed in a reactor containing an array of high-voltage needles and a grounded metallic mesh as electrodes. The deposition occurred in the discharge downstream of the plasma region. The plasma-polymerized acetylene deposits form spherical nodules on the surface of the substrates and change their wettability from hydrophilic to hydrophobic. The water contact angles of the veneer were determined with a goniometer. The capillary rise was combined with the Washburn equation to assess the change in hydrophilicity of the plasma-treated wood flour.

scholarly journals Non-fluorine surface modification of acetylated birch for improved water repellence

Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Haiyan Yin ◽  
Maziar Sedighi Moghaddam ◽  
Mikko Tuominen ◽  
Andra Dėdinaitė ◽  
Magnus Wålinder ◽  
...  
Keyword(s):  
Surface Modification ◽  
Color Change ◽  
Contact Angles ◽  
Water Repellent ◽  
Water Contact ◽  
Aesthetic Appearance ◽  
The Aesthetic ◽  
Surface Modified ◽  
Wilhelmy Plate Method ◽  
Fluorinated Surface

Abstract In this work, a non-fluorinated surface treatment, i.e., hydrophobized silicone nanofilaments, was applied on both birch and acetylated birch wood samples via a gas-phase based reaction. A superhydrophobic behavior was observed on both the surface-modified samples as revealed by the static water contact angles (CAs) greater than 160°, also valid for samples prepared with the shortest reaction time of 1 h. The dynamic wettability behavior of the samples was studied by a multicycle Wilhelmy plate method. The surface-modified acetylated birch exhibited a pronounced enhanced water resistance, resulting in very low water uptake of 3 ± 1 wt% after 100 cycles, which was not only about 29 and 5 times lower than that of the non-surface-modified birch and acetylated birch, respectively, but also three times lower than that of the surface-modified birch. Moreover, the aesthetic appearance of the acetylated wood was maintained as the surface modification only resulted in a small color change. This work shows the potential of preparing super water-repellent wood by non-fluorinated surface modification.

scholarly journals Surface Response of Fluorine Polymer-Incorporated Resin Composites to Cariogenic Biofilm Adherence

2008 ◽  
Vol 74 (5) ◽  
pp. 1428-1435 ◽  
Author(s):  
Mariko Gyo ◽  
Toru Nikaido ◽  
Koichi Okada ◽  
Junichi Yamauchi ◽  
Junji Tagami ◽  
...  
Keyword(s):  
Surface Properties ◽  
Biofilm Formation ◽  
Driving Forces ◽  
Resin Composite ◽  
Contact Angles ◽  
Biofilm Reactor ◽  
Resin Composites ◽  
Oral Biofilm ◽  
Water Contact ◽  
Pure Resin

ABSTRACT Experimental resin composites with incorporated polytetrafluoroethylene (PTFE) particles were developed, which theoretically could improve the surface properties of the materials, including the inhibition of bacterial adherence. To assess the surface properties in relation to biofilm formation and detachment, 23.1% (wt/wt) linear PTFE particles (FL-30) and cross-linked PTFE particles (FC-30) were incorporated into pure resin composites. Pure PTFE plates and pure resin composites without PTFE (F-0) were used as control specimens. Sucrose-dependent Streptococcus mutans biofilms were formed on the specimen blocks inside an oral biofilm reactor for various time periods and analyzed with or without application of driving forces. In addition, water contact angles and surface roughness were measured. The water contact angles of FL-30 (61.2°) and FC-30 (65.8°) were larger than that of F-0 (48.5°). The largest contact angle (107°) was detected on pure PTFE plates. However, the surfaces of FL-30, FC-30, and pure PTFE plates were rougher than that of F-0. Although the surface properties of the materials differed in terms of contact angles and roughness, these factors seemed not to affect biofilm formation on the surfaces within 5 h. Pure PTFE plates harbored almost the same amounts of biofilm as F-0. However, when a very strong driving force was applied, it was clear that there were significantly smaller amounts of biofilms retained on pure PTFE plates, which showed contact angles much higher than those of the other materials. Hydrophobicity of the resin composite was improved by incorporation of PTFE fillers. However, surface resistance against biofilm formation was not improved.

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