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Guido Grundmeier - One of the best experts on this subject based on the ideXlab platform.

  • inhibition of interfacial oxidative degradation during siox Plasma Polymer barrier film deposition on model organic substrates
    Plasma Processes and Polymers, 2015
    Co-Authors: Berkem Ozkaya, Felix Mitschker, Ozlem Ozcan, Peter Awakowicz, Guido Grundmeier
    Abstract:

    Interfacial processes during the initial stages of SiOx-like Plasma-Polymer barrier coating deposition were investigated by means of polarization modulation infrared reflection-absorption spectroscopy, and the resulting effect on defect densities were studied by cyclic voltammetry. Octadecanethiol self-assembled monolayers on Au-film coated wafers served as sensor layers to investigate interface chemistry during the Plasma deposition. Both the spectroscopic and electrochemical data revealed that a thin SiOCH interlayer could reduce oxidative degradation of the SAM during subsequent deposition of the SiOx barrier film from an oxygen-rich Plasma phase. The present electrochemical investigation confirmed effective inhibition of interfacial oxidative degradation processes of an aliphatic Polymer in the presence of a SiOCH interfacial layer.

  • correlation of interfacial electrode potential and corrosion resistance of Plasma Polymer coated galvanized steel part 1 ultra thin Plasma Polymer films of varying thickness
    Corrosion Science, 2010
    Co-Authors: T Titz, Guido Grundmeier, F Horzenberger, K Van Den Bergh
    Abstract:

    Abstract Ultra-thin SiO2-like Plasma Polymer films were deposited on zinc coated steel. Such films led to a strong inhibition of cathodic and anodic electrochemical reactions and a negative shift in the electrode potential. When the SiO2-like films are additionally coated with a few micron thick organic film, the resulting interface electrode potential is further shifted cathodically down to −0.8 VSHE as measured by means of a scanning Kelvin probe. This interface potential is about the same as the free corrosion potential of zinc in a chloride containing electrolyte. Accordingly, the interface proved to be extremely resistant to cathodic de-adhesion processes.

  • correlation of interfacial electrode potential and corrosion resistance of Plasma Polymer coated galvanized steel part 1 ultra thin Plasma Polymer films of varying thickness
    Corrosion Science, 2010
    Co-Authors: T Titz, Guido Grundmeier, F Horzenberger, K Van Den Bergh
    Abstract:

    Abstract Ultra-thin SiO2-like Plasma Polymer films were deposited on zinc coated steel. Such films led to a strong inhibition of cathodic and anodic electrochemical reactions and a negative shift in the electrode potential. When the SiO2-like films are additionally coated with a few micron thick organic film, the resulting interface electrode potential is further shifted cathodically down to −0.8 VSHE as measured by means of a scanning Kelvin probe. This interface potential is about the same as the free corrosion potential of zinc in a chloride containing electrolyte. Accordingly, the interface proved to be extremely resistant to cathodic de-adhesion processes.

  • correlation of interfacial electrode potential and corrosion resistance of Plasma Polymer coated galvansied steel part 2 influence of forming induced defects
    Corrosion Science, 2010
    Co-Authors: T Titz, K Van Den Bergh, F Hoerzenberger, Guido Grundmeier
    Abstract:

    Abstract Stretch forming of galvanized steel coated with ultra-thin SiO2-like Plasma Polymer films with a thickness of 10–50 nm was performed to study the formation of defects in the films and their relevance for the corrosion protection properties of the coated substrate. It is shown that the interfacial oxygen reduction is already strongly inhibited by SiO2-like films with a thickness of 10 nm. However, uniaxial stretching of these thin films leads to the formation of nanoscopic defects. The influence of nanoscopic defects in the interfacial ultra-thin films on the corrosive de-adhesion mechanisms and kinetics are studied in detail.

  • tailoring of the morphology and chemical composition of thin organosilane microwave Plasma Polymer layers on metal substrates
    Thin Solid Films, 2004
    Co-Authors: Guido Grundmeier, P Thiemann, J Carpentier, Neil J Shirtcliffe, Martin Stratmann
    Abstract:

    Abstract The growth of thin microwave organosilicon Plasma Polymers on model zinc surfaces was investigated as a function of the film thickness and the oxygen partial pressure during film deposition. The evolution of the topology of the film was studied by atomic force microscopy (AFM). The nano- and micro-roughness was investigated at the inner and the outer surfaces of the Plasma Polymers. A special etching procedure was developed to reveal the underside of the Plasma Polymer and thereby its inner surface. Rough films contained voids at the interface, which reduced the Polymer/metal contact area. The increase in oxygen partial pressure led to a smoother film growth with a perfect imitation of the substrate topography at the interface. The chemical structure of the films was determined by infrared reflection absorption spectroscopy (IRRAS), X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectroscopy (ToF-SIMS). ToF-SIMS at the outer and the inner surface of the Plasma Polymers showed that the density of methylsilyl groups increases in the outer surface layer of the Plasma Polymer and depends on the oxygen partial pressure. The chemical composition of the films could be altered to pure SiO 2 without changing the morphology by using oxygen-Plasma post-treatment. This was proved by means of IRRAS and AFM. Chemistry and topology of the films were correlated with the apparent water contact angle. It was found that a linear relationship exists between the nanoscopic roughness of the Plasma Polymer and the static contact angle of water. Superposition of a nanoscopic roughness of the metal surface and the nanoscopic roughness of methylsilyl-rich films led to ultra-hydrophobic films with water contact angles up to 160°.

Sangjin Lee - One of the best experts on this subject based on the ideXlab platform.

  • Plasma Polymer fluorocarbon thin film coated nanostructured polyethylene terephthalate surface with highly durable superhydrophobic and antireflective properties
    Polymers, 2020
    Co-Authors: Eunmi Cho, Mac Kim, Jinseong Park, Sangjin Lee
    Abstract:

    Herein, an antireflection and superhydrophobic film was obtained by uniformly forming nanostructures on the surface of polyethylene terephthalate (PET) substrate using oxygen Plasma without a pattern mask and coating Plasma-Polymer-fluorocarbon (PPFC) on the nanostructured surface by mid-range frequency sputtering. PPFC/nanostructured-PET showed a reflectance of 4.2%, which is 56% lower than that of the PET film. Haze was also improved. Nanostructured-PET exhibited a superhydrophilic surface due to Plasma deformation and a superhydrophobic surface could be realized by coating PPFC on the nanostructured surface. The PPFC coating prevented the aging of Polymer film nanostructures and showed excellent durability in a high-temperature and high-humidity environment. It exhibited excellent flexibility to maintain the superhydrophobic surface, even at a mechanical bending radius of 1 mm, and could retain its properties even after repeated bending for 10,000 times.

  • effects of carbon concentration on high hardness Plasma Polymer fluorocarbon film deposited by mid range frequency sputtering
    Scientific Reports, 2019
    Co-Authors: Sung Hyun Kim, Mac Kim, Woo Jin Choi, Jae Heung Lee, Yong Suk Yang, Sangjin Lee
    Abstract:

    We propose a method for fabricating high-hardness Plasma-Polymer-fluorocarbon (PPFC) thin films with controllable optical and surface properties via manipulation of the target composition design and sputtering power density. The carbon/polytetrafluoroethylene (PTFE) composite Polymeric material targets with the low electrical resistance were prepared by press-molding using a mechanically mixed powder of PTFE, carbon nanotubes, and graphite. The composite targets showed electrical sheet resistances of 0.1–100 Ω/sq. PPFC thin films were deposited by mid-range frequency (MF) sputtering at power densities within 0.62~4.92 W/cm2. The maximum surface hardness of the PPFC thin film was 4.75 GPa, which was 21.6 times higher than that of fluorocarbon thin film sputtered from PTFE under the same conditions. With the increase of the carbon concentration in the target, the carbon cross-linking density of the PPFC thin film increased but the fluorine concentration decreased. The concentration of fluorine in the PPFC thin films grew with increasing sputtering power density. The MF sputtered carbon-rich PPFC thin films are controllable with physical properties of optical transmittance, surface hardness and surface water repellency which could be applied as protective layers for transparent flexible devices.

  • optical electrical and surface properties of cu Plasma Polymer fluorocarbon nanocomposite thin film fabricated using metal Polymer composite target
    Applied Sciences, 2019
    Co-Authors: Sung Hyun Kim, Mac Kim, Jae Seong Park, Sangjin Lee
    Abstract:

    We propose a new method of fabricating metal–Polymer composite targets for sputtering, which makes it easier to control the composition and enables the homogeneous and reproducible fabrication of metal–Polymer nanocomposites over large areas. Using Cu/polytetrafluoroethylene composite targets containing 20, 50, and 80 wt.% Cu, Cu/Plasma Polymer fluorocarbon (PPFC) nanocomposite thin films were prepared by radio-frequency (RF) sputtering. Targets with 80 wt.% Cu were conductive; moreover, sputtering was possible not only with RF but also with mid-range frequency (MF) and direct current (DC) power sources. The nanocomposite thin film deposited by MF and DC power using an 80 wt.% Cu target showed near-metallic characteristics, exhibited absorption peaks at 618 and 678 nm, and had a surface resistance of 2 × 104 and 34.55 Ω/sq, respectively. We also analyzed the structure and composition of the Cu/PPFC nanocomposite films by X-ray diffraction and X-ray photoelectron spectroscopy. The described metal–Polymer targets can advance the applications and commercialization of nanocomposite thin films.

  • self cleaning transparent heat mirror with a Plasma Polymer fluorocarbon thin film fabricated by a continuous roll to roll sputtering process
    ACS Applied Materials & Interfaces, 2018
    Co-Authors: Sung Hyun Kim, Mac Kim, Jae Heung Lee, Sangjin Lee
    Abstract:

    This paper proposes a novel self-cleaning transparent heat mirror (SC-THM) produced by depositing a Plasma Polymer fluorocarbon thin film on a silver-and-SiNx multilayer structure fabricated by continuous roll-to-roll sputtering. The optimal structure and the thickness of each thin film of three-layer and five-layer SC-THMs were derived from optical simulation. In the five-layer SC-THM, the visible light transmittance was 60.67% at a wavelength of 406 nm and the infrared (IR) transmittance was 6.86% at a 1000 nm wavelength and 2.50% at a 1500 nm wavelength. The value of the performance parameter Tvis/Tsol was 1.70. The SC-THM exhibited self-cleaning with a very good water repellency of more than 111°, achieved by applying a low-surface-energy fluorocarbon thin film to the top layer. This study successfully demonstrated the IR blocking properties of an SC-THM through IR reflection and IR irradiation experiments.

T Titz - One of the best experts on this subject based on the ideXlab platform.

Krasimir Vasilev - One of the best experts on this subject based on the ideXlab platform.

  • Bioactive Plasma Coatings on Orthodontic Brackets: In Vitro Metal Ion Release and Cytotoxicity
    'MDPI AG', 2021
    Co-Authors: Lasni Samalka Kumarasinghe, Krasimir Vasilev, Alex Cavallaro, Neethu Ninan, Panthihage Ruvini Lakshika Dabare, Esma J. Doğramacı, Giampiero Rossi-fedele, Craig Dreyer, Peter Zilm
    Abstract:

    The metal ion release characteristics and biocompatibility of meta-based materials are key factors that influence their use in orthodontics. Although stainless steel-based alloys have gained much interest and use due to their mechanical properties and cost, they are prone to localised attack after prolonged exposure to the hostile oral environment. Metal ions may induce cellular toxicity at high dosages. To circumvent these issues, orthodontic brackets were coated with a functional nano-thin layer of Plasma Polymer and further immobilised with enantiomers of tryptophan. Analysis of the physicochemical properties confirmed the presence of functional coatings on the surface of the brackets. The quantification of metal ion release using mass spectrometry proved that Plasma functionalisation could minimise metal ion release from orthodontic brackets. Furthermore, the biocompatibility of the brackets has been improved after functionalisation. These findings demonstrate that Plasma Polymer facilitated surface functionalisation of orthodontic brackets is a promising approach to reducing metal toxicity without impacting their bulk properties

  • binding of nanoparticles to aminated Plasma Polymer surfaces is controlled by primary amine density and solution ph
    Journal of Physical Chemistry C, 2018
    Co-Authors: Shima Taheri, Peter Majewski, Andrew Michelmore, Juancarlos Ruiz, Melanie Macgregor, Renate Forch, Krasimir Vasilev
    Abstract:

    Surface nanoengineering is a valuable tool to create materials with sophisticated properties required to address unmet needs in fields such as medicine, biology or energy. This study examines the dependence of nanoparticle immobilization as a function of surface amine group density. The concentration of surface amine groups was tuned using gradients deposited from the Plasma phase of allylamine and octadiene (pp-AA/OD) precursors mixtures. Silver nanoparticles capped with carboxylic acid groups (COOH-AgNPs) were used to interrogate the effect of primary amine (−NH2) surface density on nanoparticle’s electrostatic immobilization onto freshly made and aged Plasma Polymer films. An increase in amine group density could be correlated with greater number of functionalized silver nanoparticles bound to the surface. In addition, the pp-AA/OD surface charge and nanoparticle binding density could be controlled via pH of the AgNPs colloidal solution. The results suggest that pp-AA/OD Plasma Polymer films are suitab...

  • materials displaying neural growth factor gradients and applications in neural differentiation of embryoid body cells
    Advanced Functional Materials, 2015
    Co-Authors: Bahman Delalat, Krasimir Vasilev, Agnieszka Mierczynska, Soraya Rasi Ghaemi, Alex Cavallaro, Frances J Harding, Nicolas H Voelcker
    Abstract:

    The critical growth factor density required to support neural lineage generation from mouse embryonic stem cells is assessed by constructing a surface density gradient of immobilized nerve growth factor (NGF) from a Plasma Polymer film base. A chemical surface gradient varying from high hydroxyl group density to high aldehyde group density is prepared through diffusion-controlled Plasma Polymerization of two monomers (ethanol and propionaldehyde) under a moving mask. NGF density gradients are then produced by reductive amination with the aldehyde groups on the Plasma Polymer surface. Mouse embryoid body derived (mEB) cell differentiation on the gradient surface is evaluated by immunofluorescence staining against Nestin. mEB cell density and the percentage of Nestin-positive cells increase with increasing NGF density up to a critical value corresponding to 52.9 ng cm−2, above which cell attachment and differentiation do not increase further. This gradient-based screening approach allows the growth factor surface densities to be optimized for biomaterials intended for cell differentiation or expansion, which is highly relevant to creating efficient manufacture processes for cell therapies.

  • subtle changes in surface chemistry affect embryoid body cell differentiation lessons learnt from surface bound amine density gradients
    Tissue Engineering Part A, 2014
    Co-Authors: Bahman Delalat, Krasimir Vasilev, Frances J Harding, Renee V Goreham, Nicolas H Voelcker
    Abstract:

    Advanced approaches to direct the differentiation of embryonic stem cells are highly sought after. The surface-bound chemical gradient format is a powerful screening approach that can be deployed to study changes in stem cell behavior as a function of subtle changes in surface chemistry. Here, we investigate the spontaneous differentiation of cells derived from differentiating mouse embryoid body (mEB) cells into endoderm, mesoderm, and ectoderm following culture on surface-bound gradients of chemical functional groups in the absence of differentiation-biasing bioactive factors. Gradients were created using a diffusion-controlled Plasma Polymerization technique. The generated coating ranged from hydrophobic 1,7-octadiene (OD) Plasma Polymer at one end of the gradient to a more hydrophilic allylamine (AA) Plasma Polymer on the opposite end. The gradient surface was divided into seven equal regions of progressively increasing AA Plasma Polymer content and mEB cell response within these regions was compared....

  • surface morphology in the early stages of Plasma Polymer film growth from amine containing monomers
    Plasma Processes and Polymers, 2011
    Co-Authors: Andrew Michelmore, Robert D Short, Petr Martinek, Vasu Sah, Krasimir Vasilev
    Abstract:

    The manner by which Plasma Polymers grow in the very first stages of deposition is a topic which has been almost overlooked. We show using atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) that in the early stages of Plasma deposition there are significant differences in the way Plasma Polymers grow from two amine-containing compounds onto silicon wafers. By AFM it is shown that films grown from n-heptylamine (HA) initially show 'island-like' growth before a continuous smooth film is formed. In contrast, films from allylamine grow smoothly from the very earliest stages. XPS data show substantial differences of Plasma Polymer chemistry in close proximity to the silicon surface manifested in the formation of NH + 3 and NO x species which are more abundant in films of HA. We present a possible explanation for these results based upon post-Plasma surface phenomena in the case of HA.

Mac Kim - One of the best experts on this subject based on the ideXlab platform.

  • Plasma Polymer fluorocarbon thin film coated nanostructured polyethylene terephthalate surface with highly durable superhydrophobic and antireflective properties
    Polymers, 2020
    Co-Authors: Eunmi Cho, Mac Kim, Jinseong Park, Sangjin Lee
    Abstract:

    Herein, an antireflection and superhydrophobic film was obtained by uniformly forming nanostructures on the surface of polyethylene terephthalate (PET) substrate using oxygen Plasma without a pattern mask and coating Plasma-Polymer-fluorocarbon (PPFC) on the nanostructured surface by mid-range frequency sputtering. PPFC/nanostructured-PET showed a reflectance of 4.2%, which is 56% lower than that of the PET film. Haze was also improved. Nanostructured-PET exhibited a superhydrophilic surface due to Plasma deformation and a superhydrophobic surface could be realized by coating PPFC on the nanostructured surface. The PPFC coating prevented the aging of Polymer film nanostructures and showed excellent durability in a high-temperature and high-humidity environment. It exhibited excellent flexibility to maintain the superhydrophobic surface, even at a mechanical bending radius of 1 mm, and could retain its properties even after repeated bending for 10,000 times.

  • effects of carbon concentration on high hardness Plasma Polymer fluorocarbon film deposited by mid range frequency sputtering
    Scientific Reports, 2019
    Co-Authors: Sung Hyun Kim, Mac Kim, Woo Jin Choi, Jae Heung Lee, Yong Suk Yang, Sangjin Lee
    Abstract:

    We propose a method for fabricating high-hardness Plasma-Polymer-fluorocarbon (PPFC) thin films with controllable optical and surface properties via manipulation of the target composition design and sputtering power density. The carbon/polytetrafluoroethylene (PTFE) composite Polymeric material targets with the low electrical resistance were prepared by press-molding using a mechanically mixed powder of PTFE, carbon nanotubes, and graphite. The composite targets showed electrical sheet resistances of 0.1–100 Ω/sq. PPFC thin films were deposited by mid-range frequency (MF) sputtering at power densities within 0.62~4.92 W/cm2. The maximum surface hardness of the PPFC thin film was 4.75 GPa, which was 21.6 times higher than that of fluorocarbon thin film sputtered from PTFE under the same conditions. With the increase of the carbon concentration in the target, the carbon cross-linking density of the PPFC thin film increased but the fluorine concentration decreased. The concentration of fluorine in the PPFC thin films grew with increasing sputtering power density. The MF sputtered carbon-rich PPFC thin films are controllable with physical properties of optical transmittance, surface hardness and surface water repellency which could be applied as protective layers for transparent flexible devices.

  • optical electrical and surface properties of cu Plasma Polymer fluorocarbon nanocomposite thin film fabricated using metal Polymer composite target
    Applied Sciences, 2019
    Co-Authors: Sung Hyun Kim, Mac Kim, Jae Seong Park, Sangjin Lee
    Abstract:

    We propose a new method of fabricating metal–Polymer composite targets for sputtering, which makes it easier to control the composition and enables the homogeneous and reproducible fabrication of metal–Polymer nanocomposites over large areas. Using Cu/polytetrafluoroethylene composite targets containing 20, 50, and 80 wt.% Cu, Cu/Plasma Polymer fluorocarbon (PPFC) nanocomposite thin films were prepared by radio-frequency (RF) sputtering. Targets with 80 wt.% Cu were conductive; moreover, sputtering was possible not only with RF but also with mid-range frequency (MF) and direct current (DC) power sources. The nanocomposite thin film deposited by MF and DC power using an 80 wt.% Cu target showed near-metallic characteristics, exhibited absorption peaks at 618 and 678 nm, and had a surface resistance of 2 × 104 and 34.55 Ω/sq, respectively. We also analyzed the structure and composition of the Cu/PPFC nanocomposite films by X-ray diffraction and X-ray photoelectron spectroscopy. The described metal–Polymer targets can advance the applications and commercialization of nanocomposite thin films.

  • Optical, Electrical, and Surface Properties of Cu/Plasma Polymer Fluorocarbon Nanocomposite Thin Film Fabricated Using Metal/Polymer Composite Target
    MDPI AG, 2019
    Co-Authors: Sung Hyu Kim, Mac Kim, Jae Seong Park, Sang-ji Lee
    Abstract:

    We propose a new method of fabricating metal–Polymer composite targets for sputtering, which makes it easier to control the composition and enables the homogeneous and reproducible fabrication of metal–Polymer nanocomposites over large areas. Using Cu/polytetrafluoroethylene composite targets containing 20, 50, and 80 wt.% Cu, Cu/Plasma Polymer fluorocarbon (PPFC) nanocomposite thin films were prepared by radio-frequency (RF) sputtering. Targets with 80 wt.% Cu were conductive; moreover, sputtering was possible not only with RF but also with mid-range frequency (MF) and direct current (DC) power sources. The nanocomposite thin film deposited by MF and DC power using an 80 wt.% Cu target showed near-metallic characteristics, exhibited absorption peaks at 618 and 678 nm, and had a surface resistance of 2 × 104 and 34.55 Ω/sq, respectively. We also analyzed the structure and composition of the Cu/PPFC nanocomposite films by X-ray diffraction and X-ray photoelectron spectroscopy. The described metal–Polymer targets can advance the applications and commercialization of nanocomposite thin films

  • self cleaning transparent heat mirror with a Plasma Polymer fluorocarbon thin film fabricated by a continuous roll to roll sputtering process
    ACS Applied Materials & Interfaces, 2018
    Co-Authors: Sung Hyun Kim, Mac Kim, Jae Heung Lee, Sangjin Lee
    Abstract:

    This paper proposes a novel self-cleaning transparent heat mirror (SC-THM) produced by depositing a Plasma Polymer fluorocarbon thin film on a silver-and-SiNx multilayer structure fabricated by continuous roll-to-roll sputtering. The optimal structure and the thickness of each thin film of three-layer and five-layer SC-THMs were derived from optical simulation. In the five-layer SC-THM, the visible light transmittance was 60.67% at a wavelength of 406 nm and the infrared (IR) transmittance was 6.86% at a 1000 nm wavelength and 2.50% at a 1500 nm wavelength. The value of the performance parameter Tvis/Tsol was 1.70. The SC-THM exhibited self-cleaning with a very good water repellency of more than 111°, achieved by applying a low-surface-energy fluorocarbon thin film to the top layer. This study successfully demonstrated the IR blocking properties of an SC-THM through IR reflection and IR irradiation experiments.