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Dive into the research topics where Thomas Grießer is active.

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Featured researches published by Thomas Grießer.


Carbohydrate Polymers | 2013

Interactions of a cationic cellulose derivative with an ultrathin cellulose support

Tamilselvan Mohan; Cíntia Salomão Pinto Zarth; Aleš Doliška; Rupert Kargl; Thomas Grießer; Stefan Spirk; Thomas Heinze; Karin Stana-Kleinschek

The adsorption behavior of cellulose-4-[N-methylammonium]butyrate chloride (CMABC) on two hydrophilic substrates is studied, namely nanometric cellulose model thin films and silicon dioxide substrates. The adsorption is quantified in dependence of electrolyte concentration and pH value using a quartz crystal microbalance with dissipation (QCM-D). In case of CMABC, at high ionic strengths (25-100 mM NaCl) high adsorption is observed at pH 7 (Δf(3): -15 to -17 Hz) while at lower ionic strengths (1-10 mM) less CMABC (Δf(3): -2 to -12 Hz) is deposited on the cellulose surfaces as indicated by the frequency changes using QCM-D. A change in pH value from 7 to 8 reveals an increase in adsorption. Atomic force microscopy shows that the coating of cellulose thin films with CMABC changes the morphology from a fibrillar to a particle like structure on the surface. The surface wettability with water increases with an increasing amount of CMABC on the surface compared to neat cellulose model films. At lower pH values (3 and 5), CMABC does not adsorb onto the cellulose model thin films. XPS is used to validate the results and to determine the nitrogen content of the surfaces. In addition, adsorption of CMABC onto another hydrophilic and negatively charged substrate, silicon dioxide coated quartz crystals, cannot be detected at different pH values and electrolyte concentrations as proven by QCM-D.


Langmuir | 2016

Adsorption studies of organophosphonic acids on differently activated gold surfaces

Katrin Niegelhell; Simon Leimgruber; Thomas Grießer; Christian Brandl; Boril Chernev; Robert Schennach; Gregor Trimmel; Stefan Spirk

In this study, the formation of self-assembled monolayers consisting of three organophosphonic acids (vinyl-, octyl-, and tetradecylphosphonic acid) from isopropanol solutions onto differently activated gold surfaces is studied in situ and in real time using multiparameter surface plasmon resonance (MP-SPR). Data retrieved from MP-SPR measurements revealed similar adsorption kinetics for all investigated organophosphonic acids (PA). The layer thickness of the immobilized PA is in the range of 0.6-1.8 nm corresponding to monolayer-like coverage and correlates with the length of the hydrocarbon chain of the PA molecules. After sintering the surfaces, the PA are irreversibly attached onto the surfaces as proven by X-ray photoelectron spectroscopy and attenuated total reflection infrared and grazing incidence infrared spectroscopy. Potential adsorption modes and interaction mechanisms are proposed.


RSC Advances | 2016

Reactive cellulose-based thin films – a concept for multifunctional polysaccharide surfaces

Thomas Elschner; David Reishofer; Rupert Kargl; Thomas Grießer; Thomas Heinze; Karin Stana Kleinschek

Reactive coatings of hydroxyethyl cellulose furoate in the form of thin films, suitable for the covalent immobilization of functional molecules, were developed and characterized in this work. The cellulose furoate derivatives were synthesized under homogeneous conditions by esterification of hydroxyethyl cellulose with 2-furoic acid. Reactive platform layers of these furoates were obtained by chemical surface modification of spin coated thin films with N,N′-carbonyldiimidazole. This chemistry allowed the covalent immobilization of functional molecules bearing primary and secondary amines on the films. The degree of substitution of the furoate thin films and their amino functionalized counterparts was determined gravimetrically by a quartz crystal microbalance (QCM-D) and correlated with infrared and X-ray photoelectron spectroscopy and zeta-potential measurements. Scanning electron- and atomic force microscopy showed changes in the morphologies that were influenced by the chemical reactions on the surface. The concept presented can be seen as a versatile method for immobilizing amine-containing (bio-)molecules to polysaccharide surfaces with the furoates having the potential for further reversible cross-linking in Diels–Alder reactions.


Advanced Engineering Materials | 2018

Characterization of Surface and Structure of In Situ Doped Sol-Gel-Derived Silicon Carbide

Olivia Kettner; Sanja Šimić; Birgit Kunert; Robert Schennach; Roland Resel; Thomas Grießer; Bettina Friedel

Silicon carbide (SiC), is an artificial semiconductor used for high-power transistors and blue LEDs, for its extraordinary properties. SiC would be attractive for more applications, but large-scale or large-surface area fabrication, with control over defects and surface is challenging. Sol-gel based techniques are an affordable alternative towards such requirements. This report describes two types of microcrystalline SiC derived after carbothermal reduction from sol-gel-based precursors, one with nitrogen added, the other aluminum. Characterization of their bulk, structure and surface shows that incorporation of dopants affects the formation of polytypes and surface chemistry. Nitrogen leads exclusively to cubic SiC, exhibiting a native oxide surface. Presence of aluminum instead promotes growth of hexagonal polytypes and induces self-passivation of the crystallites surface during growth. This is established by hydrogenation of silicon bonds and formation of a protecting aluminum carbonate species. XPS provides support for the suggested mechanism. This passivation is achieved in only one step, solely by aluminium in the precursor. Hence, it is shown that growth, doping and passivation of SiC can be performed as one-pot synthesis. Material without insulating oxide and a limited number of defects is highly valuable for applications involving surface-sensitive charge-transfer reactions, therefore the potential of this method is significant.


Analytical Methods | 2017

Simple method for the quantitative analysis of thin copolymer films on substrates by infrared spectroscopy using direct calibration

Martin Tazreiter; Paul Christian; Robert Schennach; Thomas Grießer; Anna Maria Coclite

Automated baseline estimation followed by least squares fitting of copolymer spectrum allows quantification in terms of comonomer volume fraction.


Polymer | 2007

UV reactive polymers for refractive index modulation based on the photo-Fries rearrangement

Thomas Höfler; Thomas Grießer; X. Gstrein; Gregor Trimmel; Georg Jakopic; Wolfgang Kern


Macromolecular Chemistry and Physics | 2008

Photo‐Fries Rearrangement in Polymeric Media: An Investigation on Fully Aromatic Esters Containing the Naphthyl Chromophore

Thomas Höfler; Thomas Grießer; Mandana Gruber; Georg Jakopic; Gregor Trimmel; Wolfgang Kern


Danube Vltava Sava Polymer Meeting - DVSPM 2017 | 2017

Study of photocleavable epoxy-anhydride networks using photosensitive o-nitrobenzyl ester links

Michael Giebler; Simone Radl; Markus Ast; Thomas Grießer; Wolfgang Kern; Sandra Schlögl


Archive | 2016

Photopolymerisierbare Monomere für den 3D Druck von biokompatiblen Strukturen

Andreas Oesterreicher; Johannes Wiener; Meinhart Roth; Andreas Moser; Florian Mostegel; Matthias Edler; Gerald Pinter; Thomas Grießer


Archive | 2016

Thiol-Yne Derived Photopolymers from Low-Cytotoxic 3D-Printing Resins

Delara Hartmann; Andreas Oesterreicher; Matthias Edler; Andreas Moser; Gerald Pinter; Thomas Grießer

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Gregor Trimmel

Graz University of Technology

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