17 results on '"Stefan Spirk"'
Search Results
2. Influence of steam jet-cooking on the rheological properties of dry and wet cationized starch solutions
- Author
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Martin Gabriel, Florian Gomernik, Esther Ferstl, Angela Chemelli, Roland Kádár, and Stefan Spirk
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Polymers and Plastics ,Organic Chemistry ,Materials Chemistry - Abstract
Steam jet-cooking allows for efficient dissolution of cationic starch in paper production as it operates above the boiling point of water at elevated pressures. However, the processes involved during jet-cooking and its consequences on dissolution and finally paper properties have not been fully resolved so far. As cationic starch is the most important paper additive in the wet end, any energy or material savings during dissolution will enhance the ecologic and economic performance of a paper mill. Here, we address the topic of solubilization of four different industrially relevant cationic starches processed via steam jet-cooking. We showcase that rheology is a useful tool to assess the solubility state of starches. Some starches featured liquid-like rheological behavior (loss moduli, G", greater than storage moduli, G') in linear viscoelastic tests and anti-thixotropic behavior in hysteresis loop tests. In contrast, cationic corn starches exhibited gel-like behavior (G' G″) and negligible hysteresis directly after cooking. HYPOTHESES: To evaluate the decisive factors for complete dissolution of industrial cationic starches using jet-cooking and to correlate them to rheological properties.
- Published
- 2021
3. Multi-layered nanoscale cellulose/CuInS2 sandwich type thin films
- Author
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Samuel Eyley, Harald Plank, Stefan Spirk, Michael Weißl, Gregor Trimmel, Wim Thielemans, Jürgen Sattelkow, and Thomas Rath
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chemistry.chemical_classification ,Spin coating ,Materials science ,Polymers and Plastics ,Sulfide ,Organic Chemistry ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Copper ,0104 chemical sciences ,Metal ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,visual_art ,Materials Chemistry ,visual_art.visual_art_medium ,Thin film ,Cellulose ,0210 nano-technology ,Nanoscopic scale ,Indium - Abstract
A generic procedure for the manufacturing of cellulose-metal sulfide multilayered sandwich type thin films is demonstrated at the example of copper indium sulfide. These multilayers were created by alternate spin coating steps of precursors, followed by their conversion using either acidic vapors, or heat treatment. As precursors, cellulose xanthate, a widely available cellulose derivative employed in viscose fiber manufacturing and commercial copper and indium xanthates were used. After conversion of the single layers into cellulose and copper indium sulfide, the film properties (structure, thickness, photoelectric activity) of the single and multilayer systems consisting of alternate layers of cellulose and copper indium sulfide were studied. For the proof of concept, up to five layers were built up, showing a clear separation of the cellulose and the metal sulfide layers as demonstrated using cross sectional analysis using ion slope beam cutting and SEM imaging. Finally, the conversion of xanthates was performed using UV light and a mask, allowing for the creation of 2D patterns. ispartof: CARBOHYDRATE POLYMERS vol:203 pages:219-227 ispartof: location:England status: published
- Published
- 2019
4. Polysaccharides for sustainable energy storage - A review
- Author
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Julian Selinger, Werner Schlemmer, Mathias Hobisch, Stefan Spirk, Graz University of Technology, Department of Bioproducts and Biosystems, Aalto-yliopisto, and Aalto University
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Battery (electricity) ,Engineering ,Polymers and Plastics ,Alginates ,Polymers ,Battery ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Electrolytes ,Electric Power Supplies ,Polysaccharides ,Still face ,Materials Chemistry ,Recycling ,Renewable Energy ,Cellulose ,Electrodes ,Nanocellulose ,Binder ,Chitosan ,Waste management ,business.industry ,Scale (chemistry) ,Alginate ,Organic Chemistry ,Industrial research ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Renewable energy ,Sustainable energy ,Cost reduction ,Separator ,Sustainability ,Nanoparticles ,0210 nano-technology ,business - Abstract
Funding Information: This work was partially funded by the Academy of Finland's Flagship Programme under Projects No. 318890 and 318891 (Competence Center for Materials Bioeconomy, FinnCERES). Publisher Copyright: © 2021 The Author(s) Copyright: Copyright 2021 Elsevier B.V., All rights reserved. The increasing amount of electric vehicles on our streets as well as the need to store surplus energy from renewable sources such as wind, solar and tidal parks, has brought small and large scale batteries into the focus of academic and industrial research. While there has been huge progress in performance and cost reduction in the past years, batteries and their components still face several environmental issues including safety, toxicity, recycling and sustainability. In this review, we address these challenges by showcasing the potential of polysaccharide-based compounds and materials used in batteries. This particularly involves their use as electrode binders, separators and gel/solid polymer electrolytes. The review contains a historical section on the different battery technologies, considerations about safety on batteries and requirements of polysaccharide components to be used in different types of battery technologies. The last sections cover opportunities for polysaccharides as well as obstacles that prevent their wider use in battery industry.
- Published
- 2021
5. Real-time adsorption of optical brightening agents on cellulose thin films
- Author
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Ulrich Hirn, Stefan Spirk, Wim Thielemans, Carina Sampl, and Samuel Eyley
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Cellulose thin film ,Optical brightening agent ,Materials science ,Polymers and Plastics ,Kinetics ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,chemistry.chemical_compound ,Adsorption ,Materials Chemistry ,Process optimization ,Trimethylsilyl cellulose ,Solubility ,Thin film ,Cellulose ,Surface plasmon resonance spectroscopy ,chemistry.chemical_classification ,Organic Chemistry ,Polymer ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Cellulose xanthate ,Chemical engineering ,chemistry ,Ionic strength ,0210 nano-technology - Abstract
Optical brightening agents (OBAs) are commonly used in textile and paper industry to adjust product brightness and color appearence. Continuous production processes lead to short residence time of the dyes in the fiber suspension, making it necessary to understand the kinetics of adsorption. The interaction mechanisms of OBAs with cellulose are challenging to establish as the fibrous nature of cellulosic substrates complicates acquisition of real-time data. Here, we explore the real-time adsorption of different OBAs (di, tetra- and hexasulfonated compounds) onto different cellulose surfaces using surface plasmon resonance spectroscopy. Ionic strength, surface topography and polarity were varied and yielded 0.76-11.35 mg m-2 OBA on cellulose. We identified four independent mechanisms governing OBA-cellulose interactions. These involve the polarity of the cellulose surface, the solubility of the OBA, the ionic strength during adsorption and presence of bivalent cations such as Ca2+. These results can be exploited for process optimization in related industries as they allow for a simple adjustment and experimental testing procedures including performance assessment of novel OBAs. ispartof: CARBOHYDRATE POLYMERS vol:261 ispartof: location:England status: published
- Published
- 2020
6. Review: Periodate oxidation of wood polysaccharides-Modulation of hierarchies
- Author
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Stefan Spirk, Juho Antti Sirviö, Tiina Nypelö, and Barbara Berke
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chemistry.chemical_classification ,Polymers and Plastics ,Organic Chemistry ,Supramolecular chemistry ,food and beverages ,Periodate ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Fibril ,Polysaccharide ,01 natural sciences ,Aldehyde ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Materials Chemistry ,Molecule ,Hemicellulose ,Cellulose ,0210 nano-technology - Abstract
Periodate oxidation of polysaccharides has transitioned from structural analysis into a modification method for engineered materials. This review summarizes the research on this topic. Fibers, fibrils, crystals, and molecules originating from forests that have been subjected to periodate oxidation can be crosslinked with other entities via the generated aldehyde functionality, that can also be oxidized or reduced to carboxyl or alcohol functionality or used as a starting point for further modification. Periodate-oxidized materials can be subjected to thermal transitions that differ from the native cellulose. Oxidation of polysaccharides originating from forests often features oxidation of structures rather than liberated molecules. This leads to changes in macro, micro, and supramolecular assemblies and consequently to alterations in physical properties. This review focuses on these aspects of the modulation of structural hierarchies due to periodate oxidation.
- Published
- 2020
7. Interaction of industrially relevant cationic starches with cellulose
- Author
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Stefan Spirk, Ulrich Hirn, Josefine Hobisch, Katrin Niegelhell, Heidemarie Reiter, Angela Chemelli, and Thomas Griesser
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Materials science ,Polymers and Plastics ,Organic Chemistry ,Size-exclusion chromatography ,Cationic polymerization ,food and beverages ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Nanocellulose ,chemistry.chemical_compound ,Adsorption ,chemistry ,Chemical engineering ,Dynamic light scattering ,Materials Chemistry ,Organic chemistry ,Particle size ,Cellulose ,Surface plasmon resonance ,0210 nano-technology - Abstract
Industrially relevant, commercially available cationic starches have been investigated towards their interaction capacity with cellulose thin films derived from trimethylsilyl cellulose (TMSC). The starches used in this study stem from different sources (potato, pea, corn) and featured rather low degrees of substitution ranging from 0.030 to 0.062. The interaction of those starches with cellulose thin films was studied by surface plasmon resonance spectroscopy under flow conditions using concentrations of 1.0mgml-1 and a flow rate of 25μlmin-1. All the investigated starches employed in this study were capable to efficiently interact with the slightly negatively charged cellulose surface leading to irreversible deposition on the surface. As complementary techniques atomic force microscopy and x-ray photoelectron spectroscopy were used to confirm the presence of the starches on the cellulose film surface. Further, dynamic light scattering and size exclusion chromatography measurements were performed to correlate adsorbed amount, particle size and molecular weight of the starches to their interaction behavior.
- Published
- 2018
8. On the formation of Bi 2 S 3 -cellulose nanocomposite films from bismuth xanthates and trimethylsilyl-cellulose
- Author
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Gregor Trimmel, David Reishofer, Christian Gspan, Heinz Amenitsch, Harald Plank, Roland Fischer, Stefan Spirk, and Heike M. A. Ehmann
- Subjects
Nanocomposite ,Materials science ,Polymers and Plastics ,Organic Chemistry ,Inorganic chemistry ,Infrared spectroscopy ,chemistry.chemical_element ,Nanoparticle ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Bismuth ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Transmission electron microscopy ,Attenuated total reflection ,Materials Chemistry ,Cellulose ,Thin film ,0210 nano-technology - Abstract
The synthesis and characterization of bismuth sulfide-cellulose nanocomposite thin films was explored. The films were prepared using organosoluble precursors, namely bismuth xanthates for Bi2S3 and trimethylsilyl cellulose (TMSC) for cellulose. Solutions of these precursors were spin coated onto solid substrates yielding homogeneous precursor films. Afterwards, a heating step under inert atmosphere led to the formation of thin nanocomposite films of bismuth sulfide nanoparticles within the TMSC matrix. In a second step, the silyl groups were cleaved off by vapors of HCl yielding bismuth sulfide/cellulose nanocomposite films. The thin films were characterized by a wide range of surface sensitive techniques such as atomic force microscopy, attenuated total reflection infrared spectroscopy, transmission electron microscopy and wettability investigations. In addition, the formation of the nanoparticle directly in the TMSC matrix was investigated in situ by GI-SWAXS using a temperature controlled sample stage.
- Published
- 2017
9. Nonspecific protein adsorption on cationically modified Lyocell fibers monitored by zeta potential measurements
- Author
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Rupert Kargl, Franz Stelzer, Claudia Payerl, Wolfgang Johann Fischer, Armin Zankel, Manuel Kaschowitz, Stefan Spirk, Matej Bračič, and Eleonore Fröhlich
- Subjects
Polymers and Plastics ,Surface Properties ,Static Electricity ,Inorganic chemistry ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Streaming current ,Adsorption ,Polymer chemistry ,Materials Chemistry ,Zeta potential ,Chitosan ,Chemistry ,Organic Chemistry ,Cationic polymerization ,Proteins ,Serum Albumin, Bovine ,Hydrogen-Ion Concentration ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Isoelectric point ,Lyocell ,Titration ,0210 nano-technology ,Protein adsorption - Abstract
Nonspecific protein deposition on Lyocell fibers via a cationization step was explored by adsorption of two different N,N,N -trimethyl chitosan chlorides (TMCs). Both, the cationization and the subsequent protein deposition steps were performed and monitored in situ by evaluating the zeta potential using the streaming potential method. Both employed TMCs (degree of substitution with N + Me 3 Cl groups: 0.27 and 0.64) irreversibly adsorb on the fibers as proven by charge reversal (−12 to +7 mV for both derivatives) after the final rinsing step. Onto these cationized fibers, BSA was deposited at different pH values (4, 5, and 7). Charge titrations revealed that close to the isoelectric point of BSA (4.7), BSA deposition was particularly favored, while at lower pH values (pH 4), hardly any adsorption took place due to electrostatic repulsion of the cationic fibers and the positively charged BSA. This work sets the foundation for further investigations to use zeta potential measurements for protein adsorption studies on fibrous materials.
- Published
- 2017
10. Cationic starches in paper-based applications—A review on analytical methods
- Author
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Ferula Thaler, Anton Huber, Stefan Spirk, Florian Stefan Gomernik, Ulrich Hirn, Wolfgang Bauer, and Angela Chemelli
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Paper ,Materials science ,Molecular Structure ,Polymers and Plastics ,Surface Properties ,Starch ,Organic Chemistry ,Cationic polymerization ,Paper production ,Nanotechnology ,02 engineering and technology ,Paper based ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,Degree of substitution ,chemistry ,Cations ,Materials Chemistry ,Particle Size ,0210 nano-technology - Abstract
This review focuses on cationic starches with a low degree of substitution (
- Published
- 2020
11. Multi-layered nanoscale cellulose/CuInS
- Author
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Michael, Weißl, Thomas, Rath, Jürgen, Sattelkow, Harald, Plank, Samuel, Eyley, Wim, Thielemans, Gregor, Trimmel, and Stefan, Spirk
- Abstract
A generic procedure for the manufacturing of cellulose-metal sulfide multilayered sandwich type thin films is demonstrated at the example of copper indium sulfide. These multilayers were created by alternate spin coating steps of precursors, followed by their conversion using either acidic vapors, or heat treatment. As precursors, cellulose xanthate, a widely available cellulose derivative employed in viscose fiber manufacturing and commercial copper and indium xanthates were used. After conversion of the single layers into cellulose and copper indium sulfide, the film properties (structure, thickness, photoelectric activity) of the single and multilayer systems consisting of alternate layers of cellulose and copper indium sulfide were studied. For the proof of concept, up to five layers were built up, showing a clear separation of the cellulose and the metal sulfide layers as demonstrated using cross sectional analysis using ion slope beam cutting and SEM imaging. Finally, the conversion of xanthates was performed using UV light and a mask, allowing for the creation of 2D patterns.
- Published
- 2018
12. Gold nanoparticles in the engineering of antibacterial and anticoagulant surfaces
- Author
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Sascha Winter, Marija Sega, Volker Ribitsch, Karin Stana-Kleinschek, Stefan Spirk, Doris Breitwieser, Christian Gspan, Heike M. A. Ehmann, Günther Koraimann, Stefan Köstler, and Uroš Maver
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Polymers and Plastics ,Surface Properties ,medicine.drug_class ,Metal Nanoparticles ,Nanoparticle ,Capsules ,Polysaccharide ,Engineering ,Blood plasma ,Escherichia coli ,Materials Chemistry ,medicine ,Humans ,Organic chemistry ,Cellulose ,chemistry.chemical_classification ,Chitosan ,Sulfates ,Organic Chemistry ,Anticoagulant ,Anticoagulants ,Quartz crystal microbalance ,Antimicrobial ,Chitosan sulfate ,Anti-Bacterial Agents ,chemistry ,Colloidal gold ,Prothrombin Time ,Partial Thromboplastin Time ,Gold ,Nuclear chemistry - Abstract
Simultaneous antibacterial and anticoagulant surfaces have been prepared by immobilization of engineered gold nanoparticles onto different kinds of surfaces. The gold nanoparticle core is surrounded by a hemocompatible, anticoagulant polysaccharide, 6-O chitosan sulfate, which serves as reduction and stabilizing agent for the generation of gold nanoparticles in a microwave mediated reaction. The particle suspension shows anticoagulant activity, which is investigated by aPTT and PT testing on citrated blood samples of three patients suffering from congenital or acquired bleeding disorders. The amount of nanoparticles deposited on the surfaces is quantified by a quartz crystal microbalance with dissipation unit. All gold containing surfaces exhibit excellent antimicrobial properties against the chosen model organism, Escherichia coli MG 1655 [R1-16]. Moreover, blood plasma coagulation times of the surfaces are increased after deposition of the engineered nanoparticles as demonstrated by QCM-D.
- Published
- 2015
13. On the formation of Bi
- Author
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David, Reishofer, Heike M, Ehmann, Heinz, Amenitsch, Christian, Gspan, Roland, Fischer, Harald, Plank, Gregor, Trimmel, and Stefan, Spirk
- Abstract
The synthesis and characterization of bismuth sulfide-cellulose nanocomposite thin films was explored. The films were prepared using organosoluble precursors, namely bismuth xanthates for Bi
- Published
- 2016
14. Interactions of a cationic cellulose derivative with an ultrathin cellulose support
- Author
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Stefan Spirk, Rupert Kargl, Karin Stana-Kleinschek, Thomas Heinze, Thomas Grießer, Tamilselvan Mohan, Aleš Doliška, and Cíntia Salomão Pinto Zarth
- Subjects
Materials science ,Polymers and Plastics ,Silicon dioxide ,Inorganic chemistry ,02 engineering and technology ,Electrolyte ,Substrate (electronics) ,010402 general chemistry ,01 natural sciences ,Contact angle ,chemistry.chemical_compound ,Adsorption ,Materials Chemistry ,Cellulose ,Aminobutyrates ,Organic Chemistry ,Quartz crystal microbalance ,Hydrogen-Ion Concentration ,Silicon Dioxide ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,chemistry ,Wetting ,0210 nano-technology ,Hydrophobic and Hydrophilic Interactions - Abstract
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 (Δ f 3 : −15 to −17 Hz) while at lower ionic strengths (1–10 mM) less CMABC (Δ f 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.
- Published
- 2013
15. Green synthesis of the silver nanoparticles mediated by pullulan and 6-carboxypullulan
- Author
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Liviu Sacarescu, Alina Spatareanu, Cristina Rîmbu, Valeria Harabagiu, Sergiu Coseri, Daniela Suteu, and Stefan Spirk
- Subjects
chemistry.chemical_classification ,Aqueous solution ,Polymers and Plastics ,Organic Chemistry ,Pullulan ,Polymer ,Crystal structure ,Silver nanoparticle ,Silver nitrate ,chemistry.chemical_compound ,chemistry ,Bromide ,Materials Chemistry ,Organic chemistry ,Surface plasmon resonance ,Nuclear chemistry - Abstract
Unoxidized and carboxylated pullulan (obtained by pullulan oxidation using TEMPO-sodium hypochlorite-sodium bromide system) have been used as mediators for the silver nanoparticles formation (AgNPs), under environment-friendly conditions: using aqueous solutions, room temperature and notably, by using both mediators as reducing and stabilizing agents. The formation of AgNPs was first screened by measuring the surface plasmon resonance peak in the range of 380-440 nm using UV-vis spectroscopy. The morphology of the synthesized silver nanoparticles was determined by TEM, which indicated that the AgNPs differ on shape and thickness of the polymer shell by varying the silver nitrate concentration, different size and shape of AgNPs was achieved. The presence of elemental silver and the crystalline structure of the AgNPs were confirmed by EDX and XRD analyses. Moreover, the possible functional groups of pullulan (oxidized pullulan) responsible for the reduction and stabilization of AgNPs were evaluated using FT-IR. The results showed that both, pullulan and 6-carboxypullulan could be successfully used as reducing as well as capping agents for the AgNPs synthesis which shows potential antimicrobial activity against Gram positive and Gram negative bacteria.
- Published
- 2013
16. Photoreductive generation of amorphous bismuth nanoparticles using polysaccharides--bismuth-cellulose nanocomposites
- Author
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Stefan Spirk, Margit Kriechbaum, Doris Breitwieser, Uwe Monkowius, Heike M. A. Ehmann, Sergiu Coseri, and Liviu Sacarescu
- Subjects
Trimethylsilyl Compounds ,Materials science ,Nanocomposite ,Polymers and Plastics ,Trimethylsilyl ,Organic Chemistry ,Inorganic chemistry ,Nanoparticle ,chemistry.chemical_element ,Metal Nanoparticles ,Toluene ,Amorphous solid ,Bismuth ,Nanocomposites ,chemistry.chemical_compound ,chemistry ,Microscopy, Electron, Transmission ,Polymer chemistry ,Materials Chemistry ,Cellulose ,Hydrophobic and Hydrophilic Interactions ,Oxidation-Reduction ,Bond cleavage - Abstract
A simple and highly reproducible synthesis of amorphous bismuth nanoparticles incorporated into a polysaccharide matrix using a photoreduction process is presented. As precursor for the generation of the Bi nanoparticles, organosoluble triphenylbismuth is used. The precursor is dissolved in toluene and mixed with a hydrophobic organosoluble polysaccharide, namely trimethylsilyl cellulose (TMSC) with high DSSi. The solution is subjected to UV exposure, which induces the homolytic cleavage of the bismuth-carbon bond in BiPh3 resulting in the formation of Bi(0) and phenyl radicals. The aggregation of the Bi atoms can be controlled in the TMSC matrix and yields nanoparticles of around 20 nm size as proven by TEM. The phenyl radicals undergo recombination to form small organic molecules like benzene and biphenyl, which can be removed from the nanocomposite after lyophilization and exposure to high vacuum. Finally, the TMSC matrix is converted to cellulose after exposure to HCl vapors, which remove the trimethylsilyl groups from the TMSC derivative. Although TMSC is converted to cellulose, the formed TMS-OH is not leaving the nanocomposite but reacts instead with surface oxide layer of the Bi nanoparticles to form silylated Bi nanoparticles as proven by TEM/EDX.
- Published
- 2013
17. Chitosan-silane sol-gel hybrid thin films with controllable layer thickness and morphology
- Author
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Karin Stana-Kleinschek, Victoria Reichel, Stefan Spirk, Nicole L. Swanson, Gerald Findenig, Aleš Doliška, Volker Ribitsch, and Rupert Kargl
- Subjects
Materials science ,Time Factors ,Polymers and Plastics ,Brachyura ,Surface Properties ,Biocompatible Materials ,Microscopy, Atomic Force ,Contact angle ,chemistry.chemical_compound ,Materials Chemistry ,Animals ,Nanotechnology ,Thin film ,Composite material ,Sol-gel ,Spin coating ,Chitosan ,Silanes ,Organic Chemistry ,Reproducibility of Results ,Silane ,Nanostructures ,chemistry ,Sarfus ,Hybrid material ,Gels - Abstract
The preparation of thin films of chitosan-silane hybrid materials by combining sol-gel processing and spin coating is reported. A variety of silanes can be used as starting materials for the preparation of such thin films, namely tetraethoxysilane, tri-tert-butoxysilanol, trimethylethoxysilane, p-trifluoromethyltetra-fluorophenyltriethoxysilane, trivinylmethoxysilane, (methoxymethyl)trimethyl-silane, and hexamethoxydisilane. These silanes are subjected to a sol-gel process before they are added to acidic chitosan solutions. The chitosan:silane ratio is kept constant at 6:1 (w/w) and dilutions with ethanol are prepared and spin coated. Depending on the degree of dilution, film thickness can be controlled in a range between 5 and 70 nm. For the determination of additional surface properties, static water contact angle measurements and atomic force microscopy have been employed.
- Published
- 2011
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