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Water Contact Angle Measurements (water + contact_angle_measurement)
Selected AbstractsComparison of two approaches to grafting hydrophilic polymer chains onto polysulfone filmsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2007Meng Tian Abstract To reduce the surface protein adsorption of polysulfone (PSf) film, we improved the hydrophilicity of this film by photochemical grafting of methoxypoly (ethylene glycol) (MPEG) derivatives on its surface. Grafting was achieved with both the simultaneous method and the sequential method. Surface analysis of the grafted film by X-ray photoelectron spectroscopy (XPS) revealed that the PEG chains had successfully grafted onto the surface of the film. The grafting efficiencies by simultaneous and sequential methods were 20.8% and 10.2%, respectively. With an atomic force microscope (AFM), the surface topography of PEG-grafted films by these two methods was compared. Static water contact angle measurement indicated that the surface hydrophilicity of the film had been improved. Protein adsorption measurement showed that the surface protein adsorption of the modified film was significantly reduced compared with that of the unmodified PSf film. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3818,3826, 2007 [source] Synthesis and characterization of novel thermoplastic poly(oligophosphazene-urethane)sPOLYMER INTERNATIONAL, Issue 6 2009Yubo Zhou Abstract BACKGROUND: Polyurethanes are some of the most popular polymers used in a variety of products, such as coatings, adhesives, flexible and rigid foams, elastomers, etc. Despite the possibility of tailoring their properties, polyurethanes suffer a serious disadvantage of poor thermal stability. Many attempts have been made in order to improve the thermal stability of polyurethanes. RESULTS: A new hydroxyl-terminated oligomer containing sulfone groups, 2,2-bis(4-hydroxy-4,4-sulfonyldiphoneloxy)tetraphenoxyoligocyclotriphosphazene (HSPPZ), was synthesized. HSPPZ was characterized using Fourier transform infrared (FTIR), NMR and gel permeation chromatography analyses. A series of novel thermoplastic poly(oligophosphazene-urethane)s were then synthesized via the reaction of NCO-terminated polyurethane prepolymer with HSPPZ containing chain-extender diols. Their structure and properties were investigated using FTIR spectroscopy, thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction, water contact angle measurement and tensile measurements. CONCLUSION: Compared to conventional thermoplastic polyurethanes, poly(oligophosphazene-urethane)s exhibit better thermal stability, low-temperature resistance and hydrophobicity, but their mechanical properties are slightly poorer. Copyright © 2009 Society of Chemical Industry [source] Enhanced Chondrogenic Responses of Human Articular Chondrocytes Onto Silk Fibroin/Wool Keratose Scaffolds Treated With Microwave-Induced Argon PlasmaARTIFICIAL ORGANS, Issue 5 2010Young Woo Cheon Abstract Silk fibroin (SF) is a natural, degradable, fibrous protein that is biocompatible, is easily processed, and possesses unique mechanical properties. Another natural material, wool keratose (WK), is a soluble derivative of wool keratin, containing amino acid sequences that induce cell adhesion. Here, we blended SF and WK to improve the poor electrospinability of WK and increase the adhesiveness of SF. We hypothesized that microwave-induced argon plasma treatment would improve chondrogenic cell growth and cartilage-specific extracellular matrix formation on a three-dimensional SF/WK scaffold. After argon plasma treatment, static water contact angle measurement revealed increased hydrophilicity of the SF/WK scaffold, and scanning electron microscopy showed that treated SF/WK scaffolds had deeper and more cylindrical pores than nontreated scaffolds. Attachment and proliferation of neonatal human knee articular chondrocytes on treated SF/WK scaffolds increased significantly, followed by increased glycosaminoglycan synthesis. Our results suggest that microwave-induced, plasma-treated SF/WK scaffolds have potential in cartilage tissue engineering. [source] The investigation of protein adsorption behaviors on different functionalized polymers filmsBIOTECHNOLOGY JOURNAL, Issue 6 2007Zhi-Hong Zhang Dr. Abstract The adsorption of BSA and fibrinogen onto plasma-polymerized di-(ethylene glycol) vinyl ether, allylamine, and maleic anhydride films were investigated in detail by surface plasmon resonance spectroscopy (SPR). The chemical properties of the plasma polymers were initially determined by the plasma deposition conditions during the generation procedure. The analysis of the chemical structure of the films and the refractive index of plasma polymers in aqueous solution was carried out using Fourier transform infrared spectroscopy and waveguide mode spectroscopy, respectively. Using water contact angle measurement, the surface wettability of plasma polymers was also characterized. These properties have a critical influence on the behavior of protein adsorption on the surface of the plasma polymers. Protein adsorption was found to depend not only on the types of functionalized groups, but also on the plasma polymer thickness since the protein molecules penetrate into the plasma polymer network bulk. According to the size of protein molecules in aqueous solution and the amount of adsorbed proteins observed by SPR, the conformational changes of proteins could be deduced. [source] Contact Angle Analysis During the Electro-oxidation of Self-Assembled Monolayers Formed by n -OctadecyltrichlorosilaneADVANCED FUNCTIONAL MATERIALS, Issue 19 2010Nicole Herzer Abstract The electrochemical oxidation process of self-assembled monolayers formed by n -octadecyltrichlorosilane (OTS) molecules on silicon wafers has been studied in a droplet of water by means of in situ water contact angle measurements. The application of different bias voltages between the substrate and a counter electrode placed into the droplet resulted in changes of the chemical nature of the monolayer, which yielded a significant alteration of the surfaces properties. Due to the changes of the wetting properties of the monolayer during the electro-oxidation process a change in the contact angles of the water droplet is concomitantly observed. This allows the in situ monitoring of the electro-oxidation process for large modified areas of several millimeters in diameter. The chosen approach represents an easy way to screen the major parameters that influence the oxidation process. Afterwards, the oxidized regions are characterized by Fourier-transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) measurements, and atomic force microscopy (AFM) investigations to obtain more information about the electro-oxidation process. The observations are correlated to experimental results obtained for oxidations performed on a smaller dimension range in the water meniscus of a conductive, biased AFM tip. A good correlation of the results in the different dimension ranges could be found. [source] Surfactive and antibacterial activity of cetylpyridinium chloride formulations in vitro and in vivoJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 6 2008Henk J. Busscher Abstract Aim: To compare effects of three cetylpyridinium chloride (CPC) formulations with and without alcohol and Tween80 on physico-chemical properties of salivary pellicles, bacterial detachment in vitro and bacterial killing in vivo. Material and Methods: Adsorption of CPC to salivary pellicles in vitro was studied using X-ray photoelectron spectroscopy and water contact angle measurements. Adhesion and detachment of a co-adhering bacterial pair was determined in vitro using a flow chamber. Killing was evaluated after live/dead staining after acute single use in vivo on 24- and 72-h-old plaques after 2-week continuous use. Results: The most pronounced effects on pellicle surface chemistry and hydrophobicity were observed after treatment with the alcohol-free formulation, while the pellicle thickness was not affected by any of the formulations. All CPC formulations detached up to 33% of the co-adhering pair from pellicle surfaces. Bacterial aggregate sizes during de novo deposition were enhanced after treatment with the alcohol-free formulation. Immediate and sustained killing in 24 and 72 h plaques after in vivo, acute single use as well as after 2-week continuous use were highest for the alcohol-free formulation. Conclusions: CPC bioavailability in a formulation without alcohol and Tween80 could be demonstrated through measures of pellicle surface properties and bacterial interactions in vitro as well as bacteriocidal actions on oral biofilms in vivo. [source] Electrochemical synthesis of PEDOT derivatives bearing imidazolium-ionic liquid moietiesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 12 2009Markus Döbbelin Abstract Novel poly(3,4-ethylenedioxythiophene) (PEDOT) polymers bearing imidazolium-ionic liquid moieties were synthesized by electrochemical polymerizations. For this purpose, new functional monomers were synthesized having an 3,4-ethylenedioxythiophene (EDOT) unit and an imidazolium-ionic liquid with different anions such as tetrafluoroborate (BF), bis(trifluoromethane)sulfonimide ((CF3SO2)2N,), and hexafluorophosphate (PF). Next, polymer films were obtained by electrochemical synthesis in dicholoromethane solutions. Obtained polymers were characterized, revealing the characteristics of PEDOT in terms of electrochemical and spectroelectrochemical properties, FTIR, 1H NMR, and AFM microscopy. Interestingly, the hydrophobic character of electropolymerized films could be modified depending on the anion type. The hydrophobicity followed the trend PF > (CF3SO2)2N, > BF > pure PEDOT as determined by water contact angle measurements. Furthermore, the polymers could be dissolved in a range of polar organic solvents such as dimethylformamide, propylene carbonate, and dimethyl sulfoxide making these polymers interesting candidates for wet processing methods. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3010,3021, 2009 [source] Photochemical attachment of polymers on planar surfaces with a covalently anchored monolayer of a novel naphthyl ketone photochemical radical generatorJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2004K. Dayananda Abstract A monolayer of covalently anchored, novel, binaphthyl ketone is used as a surface-confined photochemical radical generator (PRG) for anchoring a variety of polymers to silicon surfaces. The precursor PRG is synthesized by the application of a facile and novel method for the oxidation of sterically hindered benzylic hydrocarbons to carbonyl compounds. Oxidation was carried out with a stoichiometric amount of potassium peroxydisulfate, in the presence of a catalytic amount of copper sulfate in an acetonitrile/water mixture. The PRG synthesized is characterized by 1H NMR, UV, and Fourier transform infrared (FTIR). The covalently attached monolayers are characterized by X-ray photoelectron spectroscopy, ellipsometry, and water contact angle measurements. The method developed is applicable to the preparation of a monolayer of a variety of polymers on a wide range of substrates carrying surface hydroxyl groups. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5413,5423, 2004 [source] Investigation of a New Approach to Measuring Contact Angles for Hydrophilic Impression MaterialsJOURNAL OF PROSTHODONTICS, Issue 2 2007Gerard Kugel DMD Purpose: The purpose of this investigation was to examine the initial water contact angles of seven unset impression materials using commercially available equipment, in an effort to determine whether polyether impression materials (Impregum) have lower contact angles and are, therefore, more hydrophilic than VPS impression materials. Materials and Methods: The hydrophilic properties of unset polyether and VPS impression materials were analyzed with respect to their water contact angle measurements using the commercially available Drop Shape Analysis System DSA 10. Twenty-five data points per second were collected via video analysis. There was no delay from start of measurement and data collection. Data was collected for approximately 12 s. Droplet size was determined on the thickness of canula. If the droplets became too small in volume, the water that evaporated during the measurement was large in comparison to the volume of the droplet. Therefore, 5 ,l was chosen as the lowest volume. Five trials were conducted per series for each featured material. Contact angles were calculated using the circle fitting method. Three tests using this technique were designed to control the variables of contact angle measurement with regard to time, the varying amount of fluid in contact with impression material during clinical use, and material thickness. Sample thickness of impression material was controlled by stripping the paste flat on a glass plate using a marking template to ensure a constant film thickness. Tests were conducted in a climatized room at 24°C ± 1°C. Deionized water was used as the fluid. The device was calibrated according to manufacturer's instruction for Young,Laplace fitting prior to the measurements. Results were analyzed using One-Way ANOVA, Tukey test, and t -test, as appropriate. Results: Comparing the fast setting impression materials by One-Way ANOVA and Tukey tests (p < .05) revealed the initial contact angles to range from 66.2 ± 1.5° to 127.5 ± 4.4°, of which the polyether material was the lowest after 45 s (66.2 ± 1.5°), 120 s (70.3 ± 2.8°), and 24 h (80.3 ± 1.0°) after start of the mix. The selected times represent the different stages of unset material, ranging from 45 s as the earliest practical data collection time to 24 h, at which a stone model would be poured. The polyether materials tested exhibited lower contact angles and, thus, significantly higher initial hydrophilicity than all measured VPS materials. Additionally, Impregum impression materials are more hydrophilic in the unset stage than in the set stage. VPS may show a stepwise development of hydrophilicity in the set stage that was not observed in the unset stage. Conclusions: The polyether impression materials tested were significantly more hydrophilic before, during, and after setting than that of VPS impression materials. Regardless of the amount of water in contact with the impression material, the polyether impression materials showed a significantly higher hydrophilicity in the unset stage than the VPS materials. The initial contact angle was not dependent on the thickness of the material. All parameters, including variation of time, volume of water droplet, and thickness of material, resulted in different absolute contact angles, but did not lead to a dramatic change in the ranking of the materials with regard to their hydrophilic behavior. [source] Hydrophilization of polypropylene films by using migratory additivesJOURNAL OF VINYL & ADDITIVE TECHNOLOGY, Issue 2 2007Siqiang Zhu Linear and branched hydrophilic additives of various molecular weights (MWs) were extruded with polypropylene (PP) to make blend films. The surface-modifying additives included polyethylene glycol (PEG), hydroxyl-terminated four-arm polyethylene oxide (PEO), and a commercial hydrophilic additive, Irgasurf HL560. Films were extruded by using a twin-screw microcompounder at 200°C, and the resulting film thickness was 100 ,m. Attenuated total reflectance (ATR)-FTIR spectrometry and water contact angle measurements were performed on the film surfaces over time to investigate the additive migration behavior. Although ATR-FTIR detected concentration increases for all additives in the subsurface region, there was no significant improvement in surface hydrophilicity for the PEGs and four-arm PEOs in the same period of time as water contact angles were measured on the surfaces. Among the linear additives, low MW PEG (1 kDa) was found to migrate faster than the high MW varieties. The linear PEG and four-arm PEO with MW higher than 2 kDa did not exhibit significant migration to the surface within a month. Irgasurf was found to change the surface wettability effectively in a relatively short time. J. VINYL ADDIT. TECHNOL., 13:57,64, 2007. © 2007 Society of Plastics Engineers. [source] Fibrinolytic Poly(dimethyl siloxane) SurfacesMACROMOLECULAR BIOSCIENCE, Issue 9 2008Hong Chen Abstract PDMS surfaces have been modified to confer both resistance to non-specific protein adsorption and clot lyzing properties. The properties and chemical compositions of the surfaces have been investigated using water contact angle measurements, ATR FT-IR spectroscopy, and XPS. The ability of the PEG component to suppress non-specific protein adsorption was assessed by measurement of radiolabeled fibrinogen uptake from buffer. The adsorption of plasminogen from human plasma to the various surfaces was studied. In vitro experiments demonstrated that lysine-immobilized surfaces with free , -amino groups were able to dissolve fibrin clots, following exposure to plasma and tissue plasminogen activator. [source] A Novel ABC Triblock Copolymer with Very Low Surface Energy: Poly(dimethylsiloxane)- block -Poly(methyl methacrylate)- block -Poly(2,2,3,3,4,4,4-heptafluorobutyl methacrylate)MACROMOLECULAR REACTION ENGINEERING, Issue 5 2008Zhenghong Luo Abstract Poly(dimethylsiloxane)- block -poly(methyl methacrylate)- block -poly(2,2,3,3,4,4,4-heptafluorobutyl methacrylate) was successfully synthesized via ATRP. The chemical composition and structure of the copolymer was characterized by NMR and FT-IR spectroscopy and molecular weight measurement. Gel permeation chromatography was used to study the molecular weight distribution of the triblock copolymer. The surface properties of the resulting copolymer were investigated. The effects of fluorine content and bulk structure on surface energy were investigated by static water contact angle measurements. Surface composition was studied by XPS. [source] Interaction of Stearic Acid Deposited on Silicon Samples With Ar/N2 and Ar/O2 Atmospheric Pressure Microwave Post-dischargesPLASMA PROCESSES AND POLYMERS, Issue S1 2009Cédric Noël Abstract In this work, the interactions of a stearic acid film deposited on silicon by spin coating with the post-discharge of an Ar/N2 or Ar/O2 atmospheric pressure microwave plasma are studied. Sample surface before and after plasma treatment is analysed by means of different surface analysis methods (water contact angle measurements, XPS, ToF-SIMS and FTMS). Both plasma treatments modify the surface but with a higher etching rate for Ar/O2 post-discharges. The creation of double carbon bonds CC is observed during the treatments, with a higher quantity after Ar/N2 treatments. The mechanisms leading to modifications of stearic acid are discussed. [source] Synthesis and properties of room temperature curable trimethoxysilane-terminated polyurethane and their dispersionsPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 8 2007Sankaraiah Subramani Abstract The purpose of this research is to study the synthesis and characterization of stable aqueous dispersions of externally chain extended polyurethane/urea compositions terminated by hydrolyzable or hydrolyzed trialkoxysilane groups incorporated through secondary amino groups. These dispersions with excellent storage stability are substantially free from organic solvents which cure to water and solvent resistant, tough, scratch resistant, preferably light stable (non-yellowing) silylated polyurethane (SPU) films. The films were characterized by FT-IR, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), tensile strength and water contact angle measurements, nanoindentation, gel content, water and xylene swellability tests. The properties of the films were discussed and correlated in detail by changing length of soft segment, diisocyanates, NCO/OH ratio and chain extender, ethylenediamine (EDA). From the results, it was found that the particle size and viscosity are lower whereas the gel content and thermal stability are higher for SPUs. Modulus, hardness and tensile properties of SPU films are superior compared to EDA-PU film. Higher water contact angle and residual weight percentage of SPU films confirm silylation of PU by [3-(phenylamino)propyl]trimethoxysilane (PAPTMS). Increase in NCO/OH ratios consumes more quantity of PAPTMS which makes PU with superior mechanical properties. Higher PAPTMS content in SPU results in effective crosslinking of the functional silanol groups formed by hydrolysis reaction of trimethoxysilane groups. Overall, SPUs synthesized at 1.4 NCO/OH ratio using Poly-(oxytetramethylene)glycol (PTMG)-2000 and isophorone diisocyanate (or) toluene-2,4-diisocyanate have excellent properties compared to SPUs prepared using PTMG-1000 and at 1.2 and 1.6 NCO/OH ratios. SPUs prepared at 1.6 NCO/OH ratio are brittle due to higher crosslinking density. In addition, the crosslinking density of the films can be modified through silane end-group modification to produce SPUs with a wide range of physical properties. Copyright © 2007 John Wiley & Sons, Ltd. [source] | |||||||||||||||||||||||||