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Water Contact Angle (water + contact_angle)
Terms modified by Water Contact Angle Selected AbstractsPreparation of Water-Absorbing Polyacrylonitrile Nanofibrous MembraneMACROMOLECULAR RAPID COMMUNICATIONS, Issue 2 2006Haiqing Liu Abstract Summary: Hydrophilic acrylic nanofibers were prepared from alkaline hydrolysis of hydrophobic polyacrylonitrile (PAN) nanofibers. Water contact angle, pore volume, and liquid retention capacity of PAN nanofibrous membranes were measured to determine their dependence on hydrolysis parameters such as base concentration, temperature, and time. Vertical water retention capacity of hydrolyzed PAN nanofibrous membrane could reach as large as 200 times of that of original membrane. Fiber twinning in post-hydrolyzed PAN nanofibrous membrane. [source] H2/NH3 Plasma-Grafting of PEEK-WC-PU Membrane to Improve their cyto-Compatibility with HepatocytesPLASMA PROCESSES AND POLYMERS, Issue S1 2009Stefania Laera Abstract Plasma treatments in H2 and NH3 RF (13.56 MHz) glow discharges have been used for modifying the surface of PEEK-WC-PU membranes. Water contact angle (WCA) and X-Ray photoelectron spectroscopy (XPS) analyses were performed to study the compositional changes of PEEK-WC-PU membranes after grafting. Cell culture experiments with human hepatocytes clearly show that grafting N-containing groups improves the cyto-compatibility of the membranes. [source] Protein adsorption and platelet adhesion of polysulfone membrane immobilized with chitosan and heparin conjugatePOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 2 2003M.-C. Yang Abstract Polysulfone (PSF) membranes were treated with ozone to introduce peroxides, and then grafted with either acrylic acid or chitosan, followed by the immobilization of heparin. The effect of spacer arm on blood compatibility was investigated using three chitosans of different molecular weight [1170 (water soluble), 160,000, and 400,000] and similar degrees of deacetylation (75%). The hydrophilicity was evaluated by measuring the contact angle of water. Blood compatibility was evaluated using the activated partial thromboplastin time (APTT) as well as the adhesion of platelets. The protein affinity was determined by the absorption of human serum albumin (HSA) and human plasma fibrinogen (HPF). The results show that by the coupling of chitosan, the amount of heparin immobilized can be increased by four times. Water contact angle (from 78,° to 41,°) decreased with the increase of the amount of heparin immobilized, showing increased wettability. The heparinized PSF membrane showed longer APTT and decreasing platelet adhesion, compared to that of unmodified PSF membrane. The adsorption of HSA and HPF were reduced to 17 and 6%, respectively. This suggests that longer spacer binding to heparin can increase the opportunity of anti-coagulation on contacting blood. These results demonstrated that the hydrophilicity and blood compatibility of PSF membrane could be improved by chitosan and heparin conjugate. Copyright © 2003 John Wiley & Sons, Ltd. [source] Hydrophilic and Antimicrobial Zeolite Coatings for Gravity-Independent Water Separation,ADVANCED FUNCTIONAL MATERIALS, Issue 2 2005Abstract Condensing heat exchangers onboard manned spacecraft require hydrophilic fin surfaces to facilitate wetting and wicking of condensate to achieve gravity-independent water separation in the zero- or micro-gravity environment of space. In order to prevent the proliferation of microbes, the coating must also be biocidal. Here we show for the first time that zeolite,A and ZSM-5 coatings deposited via in-situ crystallization on stainless steel and aluminum alloys have excellent hydrophilicity, biocidal properties, and adhesion. Water contact angles below 5° were obtained on most substrates tested. When silver-ion exchange is carried out on the zeolite,A coating, it becomes highly antibacterial. This biocidal capability of zeolite,A is regenerative by repeated ion exchange. All coatings exhibit the highest rating of 5B as determined by adhesion test ASTM D-3359-02 (American Society for Testing and Materials). These properties, in addition to zeolite coating's low-temperature crystallization process and demonstrated corrosion resistance, make zeolite coatings advantageous over the current sol,gel coatings and well suited for use in condensing heat exchangers onboard manned spacecraft. [source] Plasma-induced grafting of hydroxyethyl methacrylate (HEMA) onto chitosan membranes by a swelling methodPOLYMER INTERNATIONAL, Issue 2 2003Yeping Li Abstract Hydroxyethyl methacrylate (HEMA) was grafted onto chitosan membranes by plasma-graft polymerization. Effects of monomer concentration, plasma power and plasma time on the amount of grafting were investigated. The results showed that there were two processes: grafting polymerization and etching of the membrane. The surface of the grafted membrane was evaluated by FTIR. Scanning electron microscopy indicated that the surface morphology of the grafted membrane could be adjusted through plasma power. Water contact angles of the chitosan surface decreased from 78.2° to 45.4° while the amount of grafting increased from 0 to 12.2%, indicating improved hydrophilicity of the membrane surface. Permeation coefficients through the original membrane, the membrane treated at 55,W for 15,min, and the membrane treated at 55,W for 30,min for creatinine were 9.12,×,10,7, 10.6,×,10,7 and 8.57,×,10,7,cm2,s,1, respectively. Thermogravimetry and mechanical testing showed that there were no significant changes on the bulk property of chitosan membrane after modification. © 2003 Society of Chemical Industry [source] Surface Structures and Osteoblast Activity on Biomedical Polytetrafluoroethylene Treated by Long-Pulse, High-Frequency Oxygen Plasma Immersion Ion ImplantationADVANCED ENGINEERING MATERIALS, Issue 5 2010Liping Tong Abstract Polytetrafluoroethylene (PTFE) is a biologically safe polymer used widely in clinical medicine including oral and orthopedic surgery. However, the high bio-inertness of PTFE has hampered wider applications in the biomedical fields. In this work, we extend the treatment time in long-pulse, high-frequency oxygen plasma immersion ion implantation of PTFE and a more superhydrophobic surface with a water contact angle of 160° is created. X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) reveal that the optimized long-pulse, high-frequency oxygen plasma immersion ion implantation process induces a rougher surface and to a lesser extent alters the surface oxygen concentration on the PTFE. Our data, especially long-term contact angles, suggest that the superhydrophobility stems from surface roughness alteration. Furthermore, the activity of MC3T3-E1 osteoblasts cultured on the treated surfaces is promoted in terms of quantities and morphology. [source] Organic Electronics: High Tg Cyclic Olefin Copolymer Gate Dielectrics for N,N,-Ditridecyl Perylene Diimide Based Field-Effect Transistors: Improving Performance and Stability with Thermal Treatment (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 16 2010Mater. Abstract A novel application of ethylene-norbornene cyclic olefin copolymers (COC) as gate dielectric layers in organic field-effect transistors (OFETs) that require thermal annealing as a strategy for improving the OFET performance and stability is reported. The thermally-treated N,N, -ditridecyl perylene diimide (PTCDI-C13)-based n-type FETs using a COC/SiO2 gate dielectric show remarkably enhanced atmospheric performance and stability. The COC gate dielectric layer displays a hydrophobic surface (water contact angle = 95° ± 1°) and high thermal stability (glass transition temperature = 181 °C) without producing crosslinking. After thermal annealing, the crystallinity improves and the grain size of PTCDI-C13 domains grown on the COC/SiO2 gate dielectric increases significantly. The resulting n-type FETs exhibit high atmospheric field-effect mobilities, up to 0.90 cm2 V,1 s,1 in the 20 V saturation regime and long-term stability with respect to H2O/O2 degradation, hysteresis, or sweep-stress over 110 days. By integrating the n-type FETs with p-type pentacene-based FETs in a single device, high performance organic complementary inverters that exhibit high gain (exceeding 45 in ambient air) are realized. [source] High Tg Cyclic Olefin Copolymer Gate Dielectrics for N,N,-Ditridecyl Perylene Diimide Based Field-Effect Transistors: Improving Performance and Stability with Thermal TreatmentADVANCED FUNCTIONAL MATERIALS, Issue 16 2010Jaeyoung Jang Abstract A novel application of ethylene-norbornene cyclic olefin copolymers (COC) as gate dielectric layers in organic field-effect transistors (OFETs) that require thermal annealing as a strategy for improving the OFET performance and stability is reported. The thermally-treated N,N, -ditridecyl perylene diimide (PTCDI-C13)-based n-type FETs using a COC/SiO2 gate dielectric show remarkably enhanced atmospheric performance and stability. The COC gate dielectric layer displays a hydrophobic surface (water contact angle = 95° ± 1°) and high thermal stability (glass transition temperature = 181 °C) without producing crosslinking. After thermal annealing, the crystallinity improves and the grain size of PTCDI-C13 domains grown on the COC/SiO2 gate dielectric increases significantly. The resulting n-type FETs exhibit high atmospheric field-effect mobilities, up to 0.90 cm2 V,1 s,1 in the 20 V saturation regime and long-term stability with respect to H2O/O2 degradation, hysteresis, or sweep-stress over 110 days. By integrating the n-type FETs with p-type pentacene-based FETs in a single device, high performance organic complementary inverters that exhibit high gain (exceeding 45 in ambient air) are realized. [source] Fabrication of a Superhydrophobic Surface from a Smectic Liquid-Crystal Defect ArrayADVANCED FUNCTIONAL MATERIALS, Issue 18 2009Yun Ho Kim Abstract A novel fabrication method is developed for the preparation of superhydrophobic surfaces. The procedure uses focal conic structures of semi-fluorinated smectic liquid crystals (LCs) whose periodic toric focal conic domains (TFCDs) are prepared on a surface modified substrate. Reactive ion etching (RIE) on the periodic TFCD surface leads to a superhydrophobic surface with a water contact angle of ,160° and a sliding angle of ,2° for a 10,µL water droplet. The results show that this phenomenon is due to the development of a dual-scale surface roughness arising from the nanoscale protuberance caused by applying the RIE process to the top of the microscale TFCD arrays. The unique surface behavior is further verified by demonstrating that RIE on a flat lamellar liquid crystal film, in which the director is aligned parallel with surface, results in a relatively low hydrophobicity as compared to when periodic TFCDs are subjected to REI. The observations made in this publication suggest that a new approach exists for selecting potential candidates of superhydrophic surface formation based on spontaneous self-assembly in smectic liquid-crystalline materials. [source] Addressable Protein Patterning via Switchable Superhydrophobic Microarrays,ADVANCED FUNCTIONAL MATERIALS, Issue 15 2007J.-Y. Shiu Abstract We report on a simple process to create a switchable superhydrophobic surface where the water contact angle can be switched from a superhydrophobic state (ca.,167°) to a completely wetted state (<,10°). In the superhydrophobic state, the switchable superhydrophobic surface was resistant to the adsorption of proteins. However, once converted to a wetted state, the same surface promoted protein adsorption. We have developed a novel multicomponent protein-patterning technique based on this unique property of the switchable superhydrophobic surface. It is demonstrated that up to 100,×,100 protein spots can be created within one second. Each element on the switchable superhydrophobic microarray can be addressed individually and different types of biomolecules can be selectively deposited on the microarray without losing their activity. When integrated with microfluidic channels, the switchable superhydrophobic surface allows the parallel patterning of protein molecules to be carried out without cross contamination. [source] PI3D processing of DLC coatings for different applicationsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2008S. A. Nikiforov Abstract DLC (a -C:H) and Si-DLC coatings have been deposited on various materials (steel, aluminium, silicon, glass, polymers) using a 1-m3 interior-antenna ICP PI3D facility with HMDSO and toluene as precursors. For conformal treatment of 3-D workpiececs, a low-voltage (0.5 - 1) kV, high repetition rate (up to 70 kHz) pulsing was applied. However, DLC formation on dielectric substrates was performed at higher (2 - 10) kV voltage using short (1 - 1.5) ,s pulses to minimize surface charging. Coating adhesion was achieved by formation of multi layer structure comprising Si-containing buffer layer, transient layer, DLC layer with gradually increasing hardness, and top hard DLC. Film hardness was (5 - 20) GPa, and the deposition rate (4 - 0.5) ,m/h. DLC surface roughness was (0.7 - 60) nm and water contact angle 70° - 110° depending on process parameters which implies various applications. Batch processing of sliding parts, cutting tools, glass moulds was performed. Double-side DLC coating on polymer web eliminated its rolling up due to the coating stress. With novel ICP antenna the DLC processing is promising for large-scale nano pattern transfer technology. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Remote Plasma Device for Surface Modification at Atmospheric PressurePLASMA PROCESSES AND POLYMERS, Issue S1 2009Patrick Reichen Abstract Here, a novel atmospheric plasma device is presented, which applies the (remote) afterglow of micro-barrier discharges. The study evaluates its applicability to surface modification of temperature-sensitive particulates. As such, cylindrical samples have been placed in the remote treatment zone of the device, and the effects of treatment time and variable gas mixtures on the surface wettability are investigated. Furthermore, the influence of the excess voltage in He discharge with admixtures of O2, CO2 and N2 and the effect thereof on the water contact angle is described. [source] Cover Picture: Plasma Process.PLASMA PROCESSES AND POLYMERS, Issue 2 2004Polym. Cover: The picture shows nm thick ,m long crystalline ribbons of teflon-like on a-teflon-like film which are produced in a modulated C2F4 RF discharge (duty cycle < 5%, F/C XPS,=,1.7, water contact angle > 165°). This picture is based on the research results by the group of Prof. R. d'Agostino (Bari, Italy), who is one of the four Editors-in-Chief of Plasma Processes and Polymers. [source] Cover Picture: Plasma Process.PLASMA PROCESSES AND POLYMERS, Issue 1 2004Polym. Cover: The picture shows nm thick ,m long crystalline ribbons of teflon-like on a-teflon-like film which are produced in a modulated C2F4 RF discharge (duty cycle < 5%, F/C XPS = 1.7, water contact angle >165°). This picture is based on the research results by the group of Prof. R. d'Agostino (Bari, Italy), who is one of the four Editors-in-Chief of Plasma Processes and Polymers. [source] Impact of ultraviolet radiation on HDPE and HDPE/STC blendsPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 3 2009Min Qiao Abstract The structure and properties of high-density polyethylene (HDPE) ultraviolet irradiated in ozone atmosphere were studied by FTIR, XPS, GPC, XRD, DSC, TG, gel, and contact angle test. The oxygen-containing groups such as CO, CO, and C(O)O were quickly introduced onto HDPE chains through ultraviolet irradiation in ozone atmosphere; their content increased with increase in the time of ultraviolet irradiation. Compared with those of HDPE, the molecular weight of the irradiated HDPE decreased and its distribution became wider. There was no gel in the HDPE irradiated in ozone atmosphere. After ultraviolet irradiation for short times in ozone atmosphere, the water contact angle of the irradiated HDPE decreased and its hydrophilicity was improved. The crystal shape of the irradiated HDPE was still an orthorhombic structure; its cell parameter and the face space did not alter, but its melting temperature decreased slightly. Compared with that of HDPE, the temperature of initial weight loss for irradiated HDPE decreased. The irradiated HDPE/sericite-tridymite-cristobalite (STC) blends were prepared. The dispersion and compatibility of the irradiated HDPE/STC blends were improved compared with those of HDPE/STC blends; thus its mechanical properties increased. Copyright © 2008 John Wiley & Sons, Ltd. [source] Surface modification of silicone intraocular lens by 2-methacryloyloxyethyl phosphoryl-choline binding to reduce Staphylococcus epidermidis adherenceCLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 5 2007Xiao-Dan Huang MD Abstract Purpose:, To analyse the in vitro adherence of Staphylococcus epidermidis to the 2-methacryloyl oxyethyl phosphorylcholine (MPC)-modified silicone intraocular lens (IOL). Methods:, The test IOLs were modified by using an air plasma treatment to bind MPC to the surface. The control IOLs were not modified. Chemical changes on the IOL surface were analysed by X-ray photoelectron spectroscopy (XPS) to confirm the covalent binding of MPC. IOL hydrophilicity was determined by measuring the water contact angle. Two different techniques, direct counting of viable adherent bacteria released by sonication, and scanning electron microscopy (SEM), were used to observe and compare the adherence of S. epidermidis to the IOLs after 1- and 18-h incubation. Results:, XPS analysis confirmed that the test IOLs were surface-modified with MPC. The hydrophilicity of the IOLs was improved by surface modification, and the MPC-modified IOLs exhibited significantly reduced adhesion of S. epidermidis (P = 0.002) after an incubation period of 1 h. The SEM results showed that the MPC modification also suppressed the accumulation of bacteria and biofilm production after 18 h incubation. Conclusions:, MPC-modified hydrophilic silicone IOLs reduce bacterial adherence and colonization, and thus may help reduce the incidence of postoperative endophthalmitis. [source] A novel characteristic of porous titanium oxide implantsCLINICAL ORAL IMPLANTS RESEARCH, Issue 6 2007Takashi Sawase Abstract Objective: The anatase form of titanium dioxide (TiO2) is one of the most common crystalline forms of TiO2 and is normally produced by oxidation of titanium via thermal oxidation or anodizing. This crystalline form exhibits photocatalytic activity when it is irradiated with ultraviolet A (UVA) light. The aim of the current study was to analyze the crystal structure of anodic-oxidized TiUnite® implants and to confirm the photocatalytic properties in vitro and in vivo. Material and methods: Cross-sectional observations by transmission electron microscopy were used to determine the surface crystal structure on the TiUnite implant. Subsequently, photocatalytic activity was confirmed by degradation of methylene blue, and hydrophilicity was measured based on the water contact angle. Furthermore, the in vivo effects of the photocatalytic activity of this compound were investigated. Results: An amorphous layer that was about 10 ,m thick was observed on the TiUnite implant surface. In the amorphous layer, the anatase form of the crystalline TiO2 was identified. Photocatalytic activity was clearly demonstrated by the bleaching effect of methylene blue under UVA illumination. The contact angle decreased from 44° to 11° after UVA illumination. Although these data suggest increased hydrophilicity for the TiUnite implant, the bone-to-metal contact at 4 weeks was not influenced. Conclusion: The anodic-oxidized TiUnite implant has inherent photocatalytic activity. UVA illumination increases the surface hydrophilicity of the implant. However, this increase in hydrophilicity does not improve bone apposition to the implant surface at 4 weeks. [source] Functionalized Poly(D,L -lactide) for Pulmonary Epithelial Cell CultureADVANCED ENGINEERING MATERIALS, Issue 4 2010Yuan-Min Lin Functional groups on a material surface affect the response of many cell types. As part of our strategy aimed at engineering lung tissue, we introduced functional groups into the surface of Poly(D,L -lactide) (PDLLA) films to improve its suitability for the culture of mature pulmonary epithelial cells (A549 line) using two different methods. The first method, aminolysis, can introduce primary amines into PDLLA films by transesterification using 1,15% of ethylenediamine in isopropanol. The second method, a branching modification, can generate amine-terminated or carboxylic acid-terminated tree-like branched architectures. All modified PDLLA surfaces exhibited lower water contact angles, i.e. are more hydrophilic than unmodified PDLLA. PDLLA treated with 15% ethylenediamine exhibited a rougher surface than the control, and PDLLA with branching modification had a droplet-like surface topography as visualized by atomic force microscopy (AFM). PDLLA treated with 15% ethylenediamine and branching modification with two and three generations enhanced the attachment of pulmonary epithelial cells measured using Hoechst dye. Immunostaining demonsatrated that amine-terminated branched architectures allowed for better focal adhesion point formation than the control 24,h after cell seeding. Furthermore, they also induced higher A549 cell populations and levels of activity after 4 days in culture measured using Hoechst dye and WST1 cell proliferation reagents, respectively. In contrast, carboxylic acid-terminated branching architectures were found to reduce the cell population size after 4 days. It was concluded that the concentration, type and distribution of surface functional groups can affect significantly the behavior of pulmonary epithelial cells growing on a PDLLA surface, and PDLLA film modified with two or three generations of amine-terminated branched architectures is a suitable 2D scaffold for the culture of of pulmonary epithelial cells. [source] Interaction of Zoospores of the Green Alga Ulva with Bioinspired Micro- and Nanostructured Surfaces Prepared by Polyelectrolyte Layer-by-Layer Self-AssemblyADVANCED FUNCTIONAL MATERIALS, Issue 12 2010Xinyu Cao Abstract The interaction of spores of Ulva with bioinspired structured surfaces in the nanometer,micrometer size range is investigated using a series of coatings with systematically varying morphology and chemistry, which allows separation of the contributions of morphology and surface chemistry to settlement (attachment) and adhesion strength. Structured surfaces are prepared by layer-by-layer spray-coating deposition of polyelectrolytes. By changing the pH during application of oppositely charged poly(acrylic acid) and polyethylenimine polyelectrolytes, the surface structures are systematically varied, which allows the influence of morphology on the biological response to be determined. In order to discriminate morphological from chemical effects, surfaces are chemically modified with poly(ethylene glycol) and tridecafluoroctyltriethoxysilane. This chemical modification changes the water contact angles while the influence of the morphology is retained. The lowest level of settlement is observed for structures of the order 2,µm. All surfaces are characterized with respect to their wettability, chemical composition, and morphological properties by contact angle measurement, X-ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy. [source] Plasma-induced graft polymerization of poly(ethylene glycol) on poly(methyl methacrylate) surfaces for improving antistatic propertyJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2010Yanlin Wei Abstract Ar plasma-induced graft polymerization of poly(ethylene glycol) (PEG) on Ar plasma pretreated poly(methyl methacrylate) (PMMA) surfaces was carried out to improve the antistatic properties. The surface composition and microstructure of the PEG-grafted PMMA surfaces from plasma induction were characterized by attenuated total reflectance Fourier transfer infrared (ATR-FTIR) spectroscopy, water contact angles (CA), and atomic force microscopy (AFM) measurements. The measurements revealed that the antistatic properties can be remarkably improved with the surface resistivity of PEG-grafted PMMA surface decreasing significantly by 3,6 orders of magnitude, with the optimum condition for polymerization grafted onto the Ar plasma pretreated PMMA surface being 40 W for RF power and 3 min for glow discharge time. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Organic and aqueous compatible polystyrene,maleic anhydride copolymer ultra-fine fibrous membranesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2009Corine Cécile Abstract Polystyrene,maleic anhydride copolymer (PSMA, Mv= 700 kDa) was synthesized and efficiently processed into 400 to 600 nm diameter fibers via electrospinning from either 20 wt % dimethylformamide or 25 wt % dimethylsulfoxide solution. Crosslinking of PSMA was effective by adding glycerol and poly(vinyl alcohol) (PVA) (Mw = 31,50 kDa) in the dimethylformamide and dimethylsulfoxide solutions, respectively. The PSMA fibers containing glycerol at 29.4 mol% were auto-crosslinked whereas those with 12.9 mol% (2 wt %) glycerol and 15.4 mol% (0.75 wt %) PVA required heating to induce intermolecular esterification. Heat-induced crosslinking with glycerol was more effective in rendering the PSMA fibrous membranes insoluble in all solvents whereas that with PVA remained soluble in most solvents except for acetone and tetrahydrofuran. The crosslinked fibrous membranes had improved thermally stability and retained physical integrity upon exposure (2 hr at 40°C) to carbon disulfide, the solvent for Friedel-Craft reactions of the styrene moiety. Hydrolysis (0.01N NaOH) of the auto-crosslinked fibrous membrane significantly improved its hydrophilicity by reducing the water contact angles from 90.6° to 62.5° in a matter of seconds. These ultra-high specific surface PSMA fibrous membranes have shown superior organic and aqueous solvent compatibility to be used as highly reactive and easily retrievable supports for solid-phase synthesis. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Collagen nanofilm immobilized on at surfaces by electrodeposition methodJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2009Xiudong Yang Abstract A simple electrodeposition method is presented for the preparing of collagen nanofilms (EAT) on anodic oxidized titanium surfaces (AT). The nanofilms were observed by scanning electron microscopy and atomic force microscopy. Functional TiOx layers with anionic groups of PO4, SO4 and OH were investigated on the AT surface by X-ray photoelectron spectroscopy; X-ray diffraction results indicated that the AT surface was composed mainly of anatase and rutile. The bioactive electrodeposited TiOx layers on the AT surface showed lower water contact angles and higher surface energy than pure titanium surfaces (CT) and displayed higher collagen molecule immobilization. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009 [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] Poly(N -isopropylacrylamide) Brush Fabricated by Surface-Initiated Photopolymerization and its Response to TemperatureMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 21 2009Xinyan Jia Abstract A well-defined, high-density poly(N -isopropylacrylamide) (PNIPAM) brush was fabricated through a novel and reliable strategy by the combination of the self-assembly of a monolayer of dendritic photoinitiator and surface-initiated photopolymerization. The whole fabrication process of the PNIPAM brush was followed by water contact angles, X-ray photoelectron spectroscopy, and atomic force microscopy. Characterization of the PNIPAM brush, such as molecular weight and thickness determination, were measured by gel permeation chromatography, and ellipsometry, and the graft density was estimated. The temperature response of the PNIPAM brush was further investigated and the result verified the coil-to-globule transition of the PNIPAM chains in water from low to high temperature. [source] Control of polyaniline conductivity and contact angles by partial protonationPOLYMER INTERNATIONAL, Issue 1 2008Natalia V Blinova Abstract Many studies require a specific value of conductivity when investigating conducting polymers. The conductivity of polyaniline can efficiently be controlled by partial protonation of the polyaniline base. Although this is a simple task in principle, practical guidelines are missing. In the present study, the changes in the conductivity of polyaniline base after immersion in aqueous solutions of various acids are reported. Polyaniline base has been reprotonated in aqueous solutions of picric, camphorsulfonic and phosphoric acids. The conductivity of partially reprotonated polyaniline varied between 10,9 and 100 S cm,1. The relation between the pH of a phosphoric acid solution, which was in equilibrium with polyaniline, and the conductivity , is pH = 0.77 , 0.64 log(, [S cm,1]). The wettability, i.e. water contact angles, can similarly be set by partial protonation to between 78° for polyaniline base and 44° for polyaniline reprotonated in 1 mol L,1 phosphoric acid. In solutions of picric acid, the transition from the non-conducting to the conducting state occurs over a narrow range of acid concentrations, and the tuning of conductivity is consequently difficult. Phosphoric acid is well suited for the control of conductivity of polyaniline because of the moderate dependence of the conductivity on the acid concentration or pH. Copyright © 2007 Society of Chemical Industry [source] | |||||||||||||||||||||||||