111 results on '"Stefan Spirk"'
Search Results
2. Polysaccharide Thin Films – Preparation and Analysis
- Author
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Carina Sampl and Stefan Spirk
- Published
- 2023
3. Chemical resistance of acetylated radiata pine sliced veneers
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Jana Joeressen, Georg Baumann, Stefan Spirk, Thomas Krenke, Thomas Schönauer, and Florian Feist
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General Materials Science - Published
- 2022
4. Coffee Waste-Derived Nanoporous Carbons for Hydrogen Storage
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Sebastian Stock, Nikolaos Kostoglou, Julian Selinger, Stefan Spirk, Christos Tampaxis, Georgia Charalambopoulou, Theodore Steriotis, Claus Rebholz, Christian Mitterer, Oskar Paris, University of Leoben, Department of Bioproducts and Biosystems, Graz University of Technology, Demokritos National Centre for Scientific Research, University of Cyprus, Aalto-yliopisto, and Aalto University
- Subjects
activated carbons ,coffee waste ,Materials Chemistry ,Electrochemistry ,gas sorption analysis ,Energy Engineering and Power Technology ,Chemical Engineering (miscellaneous) ,X-ray scattering ,Electrical and Electronic Engineering ,hydrogen storage ,nanoporous structures - Abstract
Publisher Copyright: © 2022 The Authors. Published by American Chemical Society. Biological waste such as residues from the food and beverage industry provides a valuable and abundant resource to be used as a precursor for the synthesis of activated carbons that can be subsequently employed as adsorbents for, e.g., hydrogen storage. Materials with a large specific surface area and pores of appropriate size are necessary to achieve reasonable hydrogen adsorption capacity. Here, we present the repeatable synthesis of activated carbons from coffee waste, i.e., spent coffee grounds and coffee silver skins, on the basis of two independently synthesized batches. The carbonization process under nitrogen gas flow followed by chemical activation with solid potassium hydroxide results in microporous carbons with bimodal pore size distribution and specific surface area up to 3300 and 2680 m2/g based on Brunauer-Emmett-Teller and density functional theory methods, respectively. The materials exhibit excellent hydrogen adsorption performance under cryogenic conditions (77 K), reaching high and fully reversible excess gravimetric hydrogen uptake values of up to 5.79 wt % at 37 bar, and total capacities exceeding 9 wt % at 100 bar.
- Published
- 2022
5. How Green are Redox Flow Batteries?
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Sophie Ebner, Stefan Spirk, Tobias Stern, and Claudia Mair‐Bauernfeind
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General Energy ,General Chemical Engineering ,Environmental Chemistry ,General Materials Science - Published
- 2023
6. Role of Intrinsic and Extrinsic Xylan in Softwood Kraft Pulp Fiber Networks
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Jana B. Schaubeder, Stefan Spirk, Lukas Fliri, Eliott Orzan, Veronika Biegler, Adelheid Bakhshi, Wolfgang Bauer, Ulrich Hirn, and Tiina Nypelö
- Published
- 2023
7. Humidity Response of Cellulose Thin Films
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David Reishofer, Roland Resel, Jürgen Sattelkow, Wolfgang J. Fischer, Katrin Niegelhell, Tamilselvan Mohan, Karin Stana Kleinschek, Heinz Amenitsch, Harald Plank, Tekla Tammelin, Eero Kontturi, Stefan Spirk, Graz University of Technology, VTT Technical Research Centre of Finland, Materials Chemistry of Cellulose, Department of Bioproducts and Biosystems, Aalto-yliopisto, and Aalto University
- Subjects
Biomaterials ,Polymers and Plastics ,Quartz Crystal Microbalance Techniques ,Materials Chemistry ,Water ,Humidity ,Bioengineering ,Cellulose ,Microscopy, Atomic Force - Abstract
Funding Information: The work was supported by the FFG project Cello-H0-4papers and the COST Action FP1205. Elettra Sincrotrone is acknowledged for providing synchrotron radiation at the Austrian SAXS beamline. The authors thank Minna Hakalahti (VTT) and Katrin Unger (TU Graz) for technical support. T.T. and E.K. acknowledge the support by FinnCERES Bioeconomy cluster. 2 Publisher Copyright: © 2022 The Authors. Published by American Chemical Society. Cellulose-water interactions are crucial to understand biological processes as well as to develop tailor made cellulose-based products. However, the main challenge to study these interactions is the diversity of natural cellulose fibers and alterations in their supramolecular structure. Here, we study the humidity response of different, well-defined, ultrathin cellulose films as a function of industrially relevant treatments using different techniques. As treatments, drying at elevated temperature, swelling, and swelling followed by drying at elevated temperatures were chosen. The cellulose films were prepared by spin coating a soluble cellulose derivative, trimethylsilyl cellulose, onto solid substrates followed by conversion to cellulose by HCl vapor. For the highest investigated humidity levels (97%), the layer thickness increased by ca. 40% corresponding to the incorporation of 3.6 molecules of water per anhydroglucose unit (AGU), independent of the cellulose source used. The aforementioned treatments affected this ratio significantly with drying being the most notable procedure (2.0 and 2.6 molecules per AGU). The alterations were investigated in real time with X-ray reflectivity and quartz crystal microbalance with dissipation, equipped with a humidity module to obtain information about changes in the thickness, roughness, and electron density of the films and qualitatively confirmed using grazing incidence small angle X-ray scattering measurements using synchrotron irradiation.
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- 2022
8. Morphology and swelling of thin films of dialcohol xylan
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Chonnipa Palasingh, Rupert Kargl, Karin Stana Kleinschek, Jana Schaubeder, Stefan Spirk, Anna Ström, and Tiina Nypelö
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Polymers and Plastics ,Organic Chemistry ,Materials Chemistry - Published
- 2023
9. How Different Carryover Pitch Extractive Components are Affecting Kraft Paper Strength
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Jussi Antero Lahti, Roman Poschner, Andrea Hochegger, Ulrich Hirn, Stefan Spirk, Werner Schlemmer, and Erich Leitner
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Softwood ,business.industry ,Chemistry ,Starch ,General Chemical Engineering ,Papermaking ,Pulp (paper) ,Paper mill ,General Chemistry ,engineering.material ,Pulp and paper industry ,Article ,chemistry.chemical_compound ,Kraft process ,engineering ,business ,QD1-999 ,Kraft paper ,Unsaturated fatty acid - Abstract
We present how harmful different wood extractives carried over to paper mill with unbleached softwood Kraft pulp are for the strength of packaging papers and boards. The investigations were done by simulating industrial papermaking conditions in laboratory-scale trials for handsheet production. It was found that fatty acids are the most relevant compounds in the carryover pitch extractives (CPEs), as they readily interfere in fiber–fiber bonding strength, control the properties of CPE micelles, and are furthermore the most abundant compounds. Addition of cationic starch improved strength and evened out the strength differences of handsheets with different CPE compounds. Oleic acid (unsaturated fatty acid) was an exception, as it was above average harmful for paper strength without cationic starch and also heavily impaired the functioning of cationic starch. As a whole, these findings demonstrate that fatty acids, especially unsaturated ones, are the most relevant CPE compounds contributing to the reduced efficiency of cationic starch and decreased strength of unbleached softwood Kraft paper. This makes the cleaning of process waters by precipitating CPEs on the pulp fibers harmful for paper strength.
- Published
- 2021
10. Interplay of electrolyte concentration and molecular weight of polyDADMAC on cellulose surface adsorption
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Carina Sampl, Jana Schaubeder, Ulrich Hirn, and Stefan Spirk
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Structural Biology ,General Medicine ,Molecular Biology ,Biochemistry - Published
- 2023
11. Surface hydrophobization of pulp fibers in paper sheets via gas phase reactions
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Stefan Spirk, Sarah Krainer, Carina Waldner, Ulrich Hirn, Eero Kontturi, Philipp Wulz, Graz University of Technology, Department of Bioproducts and Biosystems, Aalto-yliopisto, and Aalto University
- Subjects
Paper ,Materials science ,Spectrophotometry, Infrared ,Trimethylsilyl ,Silylation ,Fluoroacetates ,Acetic Anhydrides ,Palmitates ,Gas phase ,Hydrophobisation ,02 engineering and technology ,Biochemistry ,Contact angle ,03 medical and health sciences ,chemistry.chemical_compound ,Structural Biology ,Tensile Strength ,Ultimate tensile strength ,Organosilicon Compounds ,Fiber ,Cellulose ,Porosity ,Molecular Biology ,030304 developmental biology ,0303 health sciences ,Photoelectron Spectroscopy ,Water ,General Medicine ,021001 nanoscience & nanotechnology ,Fibers ,Acetic anhydride ,Ultrasonic Waves ,chemistry ,Chemical engineering ,Wettability ,Volatilization ,Trifluoroacetic anhydride ,0210 nano-technology - Abstract
Funding Information: The financial support of the Austrian Federal Ministry of Digital and Economic Affairs and the National Foundation for Research, Technology and Development , Austria, is gratefully acknowledged. We also thank the industrial partners Mondi, Canon Production Printing, Kelheim Fibres, and SIG Combibloc for their support. Publisher Copyright: © 2021 Copyright: Copyright 2021 Elsevier B.V., All rights reserved. Hydrophobization of cellulosic materials and particularly paper products is a commonly used procedure to render papers more resistant to water and moisture. Here, we explore the hydrophobization of unsized paper sheets via the gas phase. We employed three different compounds, namely palmitoyl chloride (PCl), trifluoroacetic anhydride/acetic anhydride (TFAA/Ac2O)) and hexamethyldisilazane (HMDS) which were vaporized and allowed to react with the paper sheets via the gas phase. All routes yielded hydrophobic papers with static water contact angles far above 90° and indicated the formation of covalent bonds. The PCl and TFAA approach negatively impacted the mechanical and optical properties of the paper leading to a decrease in tensile strength and yellowing of the sheets. The HMDS modified papers did not exhibit any differences regarding relevant paper technological parameters (mechanical properties, optical properties, porosity) compared to the non-modified sheets. XPS studies revealed that the HMDS modified samples have a rather low silicon content, pointing at the formation of submonolayers of trimethylsilyl groups on the fiber surfaces in the paper network. This was further investigated by penetration dynamic analysis using ultrasonication, which revealed that the whole fiber network has been homogeneously modified with the silyl groups and not only the very outer surface as for the PCl and the TFAA modified papers. This procedure yields a possibility to study the influence of hydrophobicity on paper sheets and their network properties without changing structural and mechanical paper parameters.
- Published
- 2021
12. Chemical Engineering Laboratory Projects in Student Teams in Real Life and Transformed Online: Viscose Fiber Spinning and Characterization
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Tiina Nypelö, Stefan Spirk, Gregor Kraft, Josef Innerlohinger, and Michael Weißl
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Laboratory Instruction ,Textile industry ,Engineering ,Process (engineering) ,Graduate Education/Research ,Context (language use) ,computer.software_genre ,01 natural sciences ,Education ,Viscose ,Spinning ,Laboratory Experiment ,010405 organic chemistry ,business.industry ,Organic Chemistry ,05 social sciences ,050301 education ,Hands-On Learning/Manipulatives ,General Chemistry ,Chemical Engineering ,Work in process ,Upper-Division Undergraduate ,Expert system ,0104 chemical sciences ,Cellulose fiber ,Chemical engineering ,business ,0503 education ,computer - Abstract
Chemical engineering education comprises a complexity of technical skills that include learning processes that are currently relevant in industry. Despite being a rather old industrial process, the manufacturing of viscose fibers still accounts for the major fraction of all human-made cellulosic fibers worldwide. Here we describe a laboratory setup to introduce chemistry and engineering students into the principles of cellulose fiber spinning according to the viscose process. The setup for fiber spinning is kept simplistic and allows the experiments to be performed without professional spinning equipment. However, all of the steps are performed analogously to the industrial process. The professional setting in process and chemical engineering involves work on projects and in teams. Hence, we have incorporated the fiber spinning laboratory experiment in the context of working in teams on projects. We will also present our experience on transferring a real-life laboratory experiment online, as this is required at times that online education is preferred over real-life teaching.
- Published
- 2021
13. Regenerated Cellulose Fibers as Defined Precursor Material for Activated Carbon
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Jana B. Schaubeder, Chamseddine Guizani, Julian Selinger, Andreas Mautner, Michael Hummel, and Stefan Spirk
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History ,Polymers and Plastics ,Business and International Management ,Industrial and Manufacturing Engineering - Published
- 2022
14. Rapid Separation and Quantitative Analysis of Complex Lipophilic Wood Pulp Extractive Mixtures Based on 2D Thin Layer Chromatography
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Erich Leitner, Stefan Spirk, Madeline Dächert, Andrea Walzl, Markus Gschiel, Werner Schlemmer, Melissa Sophie Egger, Jussi Antero Lahti, and Ulrich Hirn
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Chromatography ,Renewable Energy, Sustainability and the Environment ,Chemistry ,General Chemical Engineering ,Pulp (paper) ,02 engineering and technology ,General Chemistry ,respiratory system ,engineering.material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Biorefinery ,01 natural sciences ,Thin-layer chromatography ,0104 chemical sciences ,Optical sensing ,engineering ,Environmental Chemistry ,0210 nano-technology - Abstract
We present a rapid method based on 2D thin layer chromatography (TLC) for the simultaneous separation and quantification of organic, lipophilic extractives occurring in lignocellulosic biorefinerie...
- Published
- 2020
15. 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
16. Dynamic and Static Assembly of Sulfated Cellulose Nanocrystals with Alkali Metal Counter Cations
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Patrick Petschacher, Reza Ghanbari, Carina Sampl, Helmar Wiltsche, Roland Kádár, Stefan Spirk, and Tiina Nypelö
- Subjects
cellulose nanocrystals ,ion exchange ,ion pairs ,rheology ,birefringence ,rheo-PLI ,General Chemical Engineering ,General Materials Science - Abstract
Sulfate groups on cellulose particles such as cellulose nanocrystals (CNCs) provide colloidal stability credit to electrostatic repulsion between the like-charged particles. The introduction of sodium counter cations on the sulfate groups enables drying of the CNC suspensions without irreversible aggregation. Less is known about the effect of other counter cations than sodium on extending the properties of the CNC particles. Here, we introduce the alkali metal counter cations, Li+, Na+, K+, Rb+, and Cs+, on sulfated CNCs without an ion exchange resin, which, so far, has been a common practice. We demonstrate that the facile ion exchange is an efficient method to exchange to any alkali metal cation of sulfate half esters, with exchange rates between 76 and 89%. The ability to form liquid crystalline order in rest was observed by the presence of birefringence patterns and followed the Hofmeister series prediction of a decreasing ability to form anisotropy with an increasing element number. However, we observed the K-CNC rheology and birefringence as a stand-out case within the series of alkali metal modifications, with dynamic moduli and loss tangent indicating a network disruptive effect compared to the other counter cations, whereas observation of the development of birefringence patterns in flow showed the absence of self- or dynamically-assembled liquid crystalline order.
- Published
- 2022
17. Silica-based fibers with axially aligned mesopores from chitin self-assembly and sol-gel chemistry
- Author
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Bruno Alonso, Nathalie Witczak, Cyril Vallicari, Bastien Lecourt-Capdeville, Mathis Guiraud, Laurent Vachoud, Krassimir L. Kostov, Stefan Spirk, Gregor Trimmel, Emmanuel Belamie, Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM), Université de Montpellier (UM), Démarche intégrée pour l'obtention d'aliments de qualité (UMR QualiSud), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut de Recherche pour le Développement (IRD)-Avignon Université (AU)-Université de La Réunion (UR)-Institut Agro Montpellier, Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Université de Montpellier (UM), Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Institute of Bioproducts and Paper Technology, Institute for Chemistry and Technology of Materials, NAWI, École Pratique des Hautes Études (EPHE), and Université Paris sciences et lettres (PSL)
- Subjects
Fibers ,Sol-Gel ,Electrospinning ,Mechanics of Materials ,General Materials Science ,Self-assembly ,[CHIM.MATE]Chemical Sciences/Material chemistry ,General Chemistry ,Condensed Matter Physics ,Chitin Nanorods - Abstract
International audience; Polysaccharide nanorods (chitin, cellulose) can be used as colloidal templates to form silica-based mesoporous materials by combining self-assembly and sol-gel chemistry. Chitin nanorods are chosen here for their self-assembly properties, facile preparation from natural resources, and because of the complexing properties of the free amino groups at their surface in view of further functionalization. Electrospinning of ethanolic co-suspensions, containing the chitin nanorods as pore templates, siloxane oligomers as silica precursors and polyvinylpyrrolidone (PVP) as spinning polymer, allows for forming mats of hybrid organic-inorganic fibers with diameters in the 200-300 nm range. The relative proportions of each component can be adjusted to meet specific characteristics (e.g. micro-/mesoporosity ratio). After calcination, the fibers present an open porosity studied by TEM and N2 volumetry. Elongated mesopores (100-200 nm long, 2-4 nm wide) are created by individual chitin monocrystals forming the nanorods. They are highly oriented along the fibers' axes with orientational order parameters P2 > 0.95 for volume chitin contents chitin* ≥ 0.2. Additional microporosity is provided by the removal of the spinning polymer, PVP. Complementary viscosity measurements on the initial cosuspensions allow discussing the interactions between colloids and their possible impact on the materials' textures observed. The introduction of a monomeric Ti 4+ precursor in the co-suspensions leads to isolated and tetrahedral Ti units, distributed in the calcined porous silica fibers and possibly close to the pores surface. In addition, preliminary investigations on processing the fibers with a Zn xanthate as ZnS precursor leads to carbonized fibers with nanoparticles and a Zn/S molar ratio close to 1.
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- 2022
18. Recrystallization and size distribution of dislocated segments in cellulose microfibrils - a molecular dynamics perspective
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Stefan Spirk, Aart Willem Van Vuure, David Seveno, Ulrich Hirn, and Ali Khodayari
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Recrystallization (geology) ,Materials science ,Polymers and Plastics ,Cleavage (crystal) ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Molecular dynamics ,chemistry.chemical_compound ,Crystallinity ,Nanocrystal ,chemistry ,Chemical engineering ,Crystallite ,Dislocation ,Cellulose ,0210 nano-technology - Abstract
Abstract The arrangement of cellulose molecules in natural environment on the nanoscale is still not fully resolved, with longitudinal disorder in cellulose microfibrils (CMF) being one relevant question. Particularly the length of the dislocated cellulose segments in CMFs is still under debate. Using molecular dynamics simulations, we are first investigating the phenomenon of pseudo-recrystallization of dislocated cellulose regions after cleavage of CMFs. Based on our simulations we propose that 3–4 glucose residues bordering to each side of a cellulose nanocrystal are actually reorganizing to a quasi-crystalline state, which are corroborating recent analytical investigations reporting an increase in crystallinity after acid vapor hydrolysis of CMFs. Combining our molecular dynamics simulation results with these analytical data we can estimate the length of the dislocated cellulose segments in CMFs. We propose that, for the investigated sources of biomass (cotton and ramie), the dislocation lengths are between 3.1–5.8 nm equaling to 6–11 glucose residues in the cellulose crystallites. Graphic abstract
- Published
- 2021
19. Cellulose carbamate derived cellulose thin films: preparation, characterization and blending with cellulose xanthate
- Author
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Leena-Sisko Johansson, Bert Volkert, Michael Weißl, Kay Hettrich, Stefan Spirk, Mathias Hobisch, Eero Kontturi, and Publica
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cellulose carbamate ,all cellulose blend films ,Carbamate ,Materials science ,Polymers and Plastics ,Cellulose xanthate ,medicine.medical_treatment ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,chemistry.chemical_compound ,medicine ,Cellulose ,Thin film ,cellulose xanthate ,cellulose swelling ,Spin coating ,Aqueous solution ,Quartz crystal microbalance ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Characterization (materials science) ,chemistry ,Chemical engineering ,cellulose thin film ,0210 nano-technology - Abstract
Cellulose carbamate (CC) was employed as a water-soluble precursor in the manufacturing of cellulose based thin films using the spin coating technique. An intriguing observation was that during spin coating of CC from alkaline aqueous solutions, regeneration to cellulose was accomplished without the addition of any further chemicals. After rinsing, homogeneous thin films with tunable layer thickness in a range between 20 and 80 nm were obtained. Further, CC was blended with cellulose xanthate in different ratios (3:1, 1:1, 1:3) and after regeneration the properties of the resulting all-cellulose blend thin films were investigated. We could observe some slight indications of phase separation by means of atomic force microscopy. The layer thickness of the blend thin films was nearly independent of the ratio of the components, with values between 50 and 60 nm for the chosen conditions. The water uptake capability (80-90% relative to the film mass) determined by H2O/D2O exchange in a quartz crystal microbalance was independent of the blend ratio.
- Published
- 2019
20. Cobalt Ferrite Nanoparticles for Three-Dimensional Visualization of Micro- and Nanostructured Cellulose in Paper
- Author
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Wolfgang Johann Fischer, Armin Zankel, Simon Zabler, Wolfgang Bauer, Mathias Hobisch, Dominik Müller, Stefan Spirk, Rene Eckhart, and Publica
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Cellulose fiber ,chemistry.chemical_compound ,Materials science ,chemistry ,Three dimensional visualization ,Composite number ,Energy-dispersive X-ray spectroscopy ,Cobalt ferrite nanoparticles ,General Materials Science ,Context (language use) ,Nanotechnology ,Fiber ,Cellulose - Abstract
Iron cobalt ferrite nanoparticles were used for the detection of micro- and nanostructured cellulose fibers in a cellulose network. Since extraction and modification of these fibers from lignocellulosic plants have undergone a significant increase in efficiency, nowadays composites containing these materials are a major research line in academia and industry. A particularly interesting composite in this context is paper, a nonwoven material where cellulose fibers form a network which is held together mainly by fiber-fiber interactions. In this composite, there is a certain fraction of micro- and nanostructured celluloses present, the so-called fines. Their impact on paper properties is still under debate, and one of the major factors influencing the properties, namely, their distribution inside the paper, remains elusive so far. Here, we present an approach which allows for the detection of these micro- and nanostructured celluloses in paper sheets by combining imaging technologies labeling the fine fibers with inorganic nanoparticles. The addition of these labeled materials during the paper manufacturing process enables imaging in scanning electron microscopy/energy-dispersive X-ray spectroscopy experiments and provides contrast in X-ray microtomography. Using a combination of these two techniques, the location of the fines in the paper sheets was evaluated and quantified, pointing at deposition in pores of the paper as well as at fiber-fiber junctions. We demonstrate that the tensile indices, air permeability, and the water retention value of handsheets were not altered by the addition of labeled fines compared to sheets where nonlabeled fines have been added.
- Published
- 2019
21. Multi-layered nanoscale cellulose/CuInS2 sandwich type thin films
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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
22. 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
23. Visualizing Degradation of Cellulose Nanofibers by Acid Hydrolysis
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Muhammad Awais, Timo Pääkkönen, Panagiotis Spiliopoulos, Eero Kontturi, Leena Pitkänen, Stefan Spirk, Kirsi Svedström, Mira Viljanen, Materials Chemistry of Cellulose, Graz University of Technology, Department of Bioproducts and Biosystems, University of Helsinki, Aalto-yliopisto, and Aalto University
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Polymers and Plastics ,Nanofibers ,Bioengineering ,02 engineering and technology ,010402 general chemistry ,order/disorder transitions ,01 natural sciences ,Article ,Nanocellulose ,Biomaterials ,chemistry.chemical_compound ,Crystallinity ,Hydrolysis ,X-Ray Diffraction ,cellulose degradation ,Materials Chemistry ,Cellulose ,nanocellulose ,Molar mass ,atomic force microscopy ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Cellulose fiber ,chemistry ,Chemical engineering ,Nanofiber ,Nanoparticles ,Acid hydrolysis ,0210 nano-technology - Abstract
Cellulose hydrolysis is an extensively studied process due to its relevance in the fields of biofuels, chemicals production, and renewable nanomaterials. However, the direct visualization of the process accompanied with detailed scaling has not been reported because of the vast morphological alterations occurring in cellulosic fibers in typical heterogeneous (solid/liquid) hydrolytic systems. Here, we overcome this distraction by exposing hardwood cellulose nanofibers (CNFs) deposited on silica substrates to pressurized HCl gas in a solid/gas system and examine the changes in individual CNFs by atomic force microscopy (AFM). The results revealed that hydrolysis proceeds via an intermediate semi-fibrous stage before objects reminiscent of cellulose nanocrystals were formed. The length of the nanocrystal-like objects correlated well with molar mass, as analyzed by gel permeation chromatography, performed on CNF aerogels hydrolyzed under identical conditions. Meanwhile, X-ray diffraction showed a slight increasein crystallinity index as the hydrolysis proceeded. The results provide a modern visual complement to >100 years of research in cellulose degradation.
- Published
- 2021
24. 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
25. Review: Periodate oxidation of wood polysaccharides-Modulation of hierarchies
- Author
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Stefan Spirk, Juho Antti Sirviö, Tiina Nypelö, and Barbara Berke
- Subjects
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
26. 2-Methoxyhydroquinone from Vanillin for Aqueous Redox-Flow Batteries
- Author
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Philipp Frühwirt, Wolfgang Kern, Werner Schlemmer, Stefan Spirk, Philipp Nothdurft, Gisbert Riess, Max Schmallegger, Alina Petzold, Stefan Freunberger, Georg Gescheidt-Demner, and Roland Fischer
- Subjects
quinone ,Aqueous solution ,Semiquinone ,Chemistry ,Radical ,Communication ,Inorganic chemistry ,redox-flow batteries ,lignin ,General Chemistry ,Electrolyte ,General Medicine ,Energy Storage ,Electrochemistry ,Flow battery ,Redox ,Catalysis ,Communications ,Quinone ,vanillin - Abstract
We show the synthesis of a redox‐active quinone, 2‐methoxy‐1,4‐hydroquinone (MHQ), from a bio‐based feedstock and its suitability as electrolyte in aqueous redox flow batteries. We identified semiquinone intermediates at insufficiently low pH and quinoid radicals as responsible for decomposition of MHQ under electrochemical conditions. Both can be avoided and/or stabilized, respectively, using H3PO4 electrolyte, allowing for reversible cycling in a redox flow battery for hundreds of cycles., A vanillin‐based 2‐methoxyhydroquinone is proposed as the catholyte for redox‐flow batteries. We overcame the tendency of such quinones to form reactive radicals that trigger side‐reactions by carefully choosing the medium. This enabled 87.4 % capacity retention after 250 cycles.
- Published
- 2020
27. Biopolymer Thin Films and Coatings
- Author
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Stefan Spirk, Eero Kontturi, and Tiina Nypelö
- Subjects
Chitosan ,chemistry.chemical_compound ,Materials science ,chemistry ,Chemical engineering ,engineering ,Biopolymer ,engineering.material ,Cellulose ,Thin film - Published
- 2020
28. Structural Order in Cellulose Thin Films Prepared from a Trimethylsilyl Precursor
- Author
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Benedikt Schrode, Birgit Kunert, Andrew O. F. Jones, Eero Kontturi, Christian Röthel, Stefan Spirk, David Reishofer, Eduardo Machado-Charry, Ingo Salzmann, and Roland Resel
- Subjects
Diffraction ,Trimethylsilyl Compounds ,Materials science ,Polymers and Plastics ,Spectrophotometry, Infrared ,Polymers ,Infrared spectroscopy ,Bioengineering ,02 engineering and technology ,engineering.material ,010402 general chemistry ,Microscopy, Atomic Force ,01 natural sciences ,Biomaterials ,chemistry.chemical_compound ,X-Ray Diffraction ,Phase (matter) ,Materials Chemistry ,Thin film ,Cellulose ,chemistry.chemical_classification ,Polymer ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Crystallography ,Nanocrystal ,chemistry ,engineering ,Nanoparticles ,Biopolymer ,0210 nano-technology - Abstract
Biopolymer cellulose is investigated in terms of the crystallographic order within thin films. The films were prepared by spin-coating of a trimethylsilyl cellulose precursor followed by an exposure to HCl vapors; two different source materials were used. Careful precharacterization of the films was performed by infrared spectroscopy and atomic force microscopy. Subsequently, the films were investigated by grazing incidence X-ray diffraction using synchrotron radiation. The results showed broad diffraction peaks, indicating a rather short correlation length of the molecular packing in the range of a few nanometers. The analysis of the diffraction patterns was based on the known structures of crystalline cellulose, as the observed peak pattern was comparable to cellulose phase II and phase III. The dominant fraction of the film is formed by two different types of layers, which are oriented parallel to the substrate surface. The stacking of the layers results in a one-dimensional crystallographic order with a defined interlayer distance of either 7.3 or 4.2 A. As a consequence, two different preferred orientations of the polymer chains are observed. In both cases, polymer chain axes are aligned parallel to the substrate surface, and the orientation of the cellulose molecules are concluded to be either edge-on or flat-on. A minor fraction of the cellulose molecules form nanocrystals that are randomly distributed within the films. In this case, the molecular packing density was found to be smaller in comparison to the known crystalline phases of cellulose.
- Published
- 2019
29. Biopolymer Thin Films and Coatings
- Author
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Stefan Spirk, Tiina Nypelö, and Eero Kontturi
- Subjects
010407 polymers ,Materials science ,lignin ,coatings ,engineering.material ,01 natural sciences ,lcsh:Chemistry ,Chitosan ,chemistry.chemical_compound ,biopolymer ,Lignin ,Thin film ,Cellulose ,General Chemistry ,proteins ,cellulose ,0104 chemical sciences ,Chemistry ,Editorial ,thin films ,lcsh:QD1-999 ,chemistry ,Chemical engineering ,engineering ,Biopolymer ,chitosan - Published
- 2019
30. 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
- Subjects
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
31. Homogeneous cellulose thin films by regeneration of cellulose xanthate: properties and characterization
- Author
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Stefan Spirk, Michael Weißl, Josef Innerlohinger, David Reishofer, Katrin Niegelhell, and Armin Zankel
- Subjects
Spin coating ,Aqueous solution ,Materials science ,Polymers and Plastics ,biology ,Inorganic chemistry ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,biology.protein ,Wafer ,Xanthate ,Cellulose ,Bovine serum albumin ,Thin film ,0210 nano-technology ,Spectroscopy - Abstract
The preparation and characterization of cellulose thin films derived from cellulose xanthate is reported. The films are prepared by depositing alkaline aqueous solutions of cellulose xanthate onto silicon wafers, followed by a spin coating step. Depending on the xanthate concentration used for spin coating, films with 50 and 700 nm thickness are obtained. The cellulose xanthate is converted to cellulose by exposing the films to HCl vapors over a period of 20 min. The conversion is monitored by ATR-IR spectroscopy, which allows for tracking the rupture of C–S and C=S bonds during the regeneration process. The conversion is accompanied by a reduction of the film thickness of ca 40% due to the removal of the bulky xanthate group. The films feature a homogenous, but porous morphology as shown by atomic force microscopy. Further, the films were investigated towards their interaction with Bovine Serum Albumin (BSA) and fibrinogen by means of multi-parameter surface plasmon resonance spectroscopy. Similar as other cellulose thin films BSA adsorption is low while fibrinogen adsorbs to some extent at physiological pH (7.4).
- Published
- 2017
32. How Bound and Free Fatty Acids in Cellulose Films Impact Nonspecific Protein Adsorption
- Author
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Katrin Niegelhell, Stefan Spirk, Yonggui Wang, Michael Süßenbacher, Harald Plank, Jürgen Sattelkow, and Kai Zhang
- Subjects
Polymers and Plastics ,Surface Properties ,Serum albumin ,Bioengineering ,02 engineering and technology ,Fatty Acids, Nonesterified ,Microscopy, Atomic Force ,010402 general chemistry ,01 natural sciences ,Biomaterials ,chemistry.chemical_compound ,Adsorption ,Materials Chemistry ,Organic chemistry ,Cellulose ,Bovine serum albumin ,chemistry.chemical_classification ,Spin coating ,biology ,Chemistry ,Proteins ,food and beverages ,Fatty acid ,Serum Albumin, Bovine ,Surface Plasmon Resonance ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Solutions ,Chemical engineering ,biology.protein ,Stearic acid ,0210 nano-technology ,Stearic Acids ,Protein adsorption - Abstract
The effect of fatty acids and fatty acid esters to impair nonspecific protein adsorption on cellulose thin films is investigated. Thin films are prepared by blending trimethylsilyl cellulose solutions with either cellulose stearoyl ester or stearic acid at various ratios. After film formation by spin coating, the trimethylsilyl cellulose fraction of the films is converted to cellulose by exposure to HCl vapors. The morphologies and surface roughness of the blends were examined by atomic force microscopy revealing different feature shapes and sizes depending on the blend ratios. Nonspecific protein adsorption at the example of bovine serum albumin toward the blend thin films was tested by means of surface plasmon resonance spectroscopy in real-time. Incorporation of stearic acid into the cellulose leads to highly protein repellent surfaces regardless of the amount added. The stearic acid acts as a sacrificial compound that builds a complex with bovine serum albumin thereby inhibiting protein adsorption. For the blends where stearoyl ester is added to the cellulose films, the cellulose:cellulose stearoyl ester ratios of 3:1 and 1:1 lead to much lower nonspecific protein adsorption compared to pure cellulose, whereas for the other ratios, adsorption increases. Supplementary results were obtained from atomic force microscopy experiments performed in liquid during exposure to protein solution and surface free energy determinations.
- Published
- 2017
33. Cellulose Nanocrystals/Chitosan-Based Nanosystems: Synthesis, Characterization, and Cellular Uptake on Breast Cancer Cells
- Author
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Stefan Spirk, Ricardo J.B. Pinto, Nicole S. Lameirinhas, Helena Oliveira, Iola F. Duarte, Carla Vilela, Gustavo H. Rodrigues da Silva, Carmen S. R. Freire, Párástu Oskoei, and Gabriela Guedes
- Subjects
Chemistry ,Ligand ,fluorescein isothiocyanate ,General Chemical Engineering ,cellular uptake ,nanosystems ,Fluorescence ,Article ,Imaging agent ,Chitosan ,folic acid ,chemistry.chemical_compound ,physical adsorption ,Folate receptor ,folate receptor-positive cancer cells ,Cancer cell ,Biophysics ,General Materials Science ,chitosan ,Nanocarriers ,Fluorescein isothiocyanate ,QD1-999 ,cellular exometabolomics ,cellulose nanocrystals - Abstract
Cellulose nanocrystals (CNCs) are elongated biobased nanostructures with unique characteristics that can be explored as nanosystems in cancer treatment. Herein, the synthesis, characterization, and cellular uptake on folate receptor (FR)-positive breast cancer cells of nanosystems based on CNCs and a chitosan (CS) derivative are investigated. The physical adsorption of the CS derivative, containing a targeting ligand (folic acid, FA) and an imaging agent (fluorescein isothiocyanate, FITC), on the surface of the CNCs was studied as an eco-friendly methodology to functionalize CNCs. The fluorescent CNCs/FA-CS-FITC nanosystems with a rod-like morphology showed good stability in simulated physiological and non-physiological conditions and non-cytotoxicity towards MDA-MB-231 breast cancer cells. These functionalized CNCs presented a concentration-dependent cellular internalization with a 5-fold increase in the fluorescence intensity for the nanosystem with the higher FA content. Furthermore, the exometabolic profile of the MDA-MB-231 cells exposed to the CNCs/FA-CS-FITC nanosystems disclosed a moderate impact on the cells’ metabolic activity, limited to decreased choline uptake and increased acetate release, which implies an anti-proliferative effect. The overall results demonstrate that the CNCs/FA-CS-FITC nanosystems, prepared by an eco-friendly approach, have a high affinity towards FR-positive cancer cells and thus might be applied as nanocarriers with imaging properties for active targeted therapy.
- Published
- 2021
34. 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
35. 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
36. Biobased Cellulosic–CuInS2 Nanocomposites for Optoelectronic Applications
- Author
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Heinz Amenitsch, Gregor Trimmel, David Reishofer, Bruno Alonso, Harald Plank, Christian Gspan, Emmanuel Belamie, Thomas Rath, Heike M. A. Ehmann, Stefan Spirk, and Sebastian Dunst
- Subjects
Materials science ,General Chemical Engineering ,Composite number ,Nanoparticle ,chemistry.chemical_element ,02 engineering and technology ,Thermal treatment ,engineering.material ,010402 general chemistry ,01 natural sciences ,7. Clean energy ,law.invention ,chemistry.chemical_compound ,law ,Solar cell ,Environmental Chemistry ,Cellulose ,Nanocomposite ,Renewable Energy, Sustainability and the Environment ,business.industry ,General Chemistry ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,chemistry ,engineering ,Optoelectronics ,Biopolymer ,0210 nano-technology ,business ,Indium - Abstract
A generic approach to design optoelectronic devices using renewable biopolymers is demonstrated. As a proof of principle, a biopolymer/CuInS2 nanocomponent-based solar cell has been assembled by using a cellulose derivative with a reasonable life cycle performance, namely, trimethylsilyl cellulose (TMSC). The solar cells are manufactured using a mixture of copper and indium xanthates as precursors, which decompose and form CIS nanoparticles within the biopolymer matrix during a thermal treatment, which was investigated by in situ combined grazing incidence small and wide-angle X-ray scattering experiments. The growth of the nanoparticles is thereby controlled by the TMSC matrix. The nanocrystals exhibit an average diameter of approximately 4 nm. Using this composite, it was possible to fabricate solar cells, generating current in a wide range of the solar spectrum and exhibiting power conversion efficiencies of ca. 1%.
- Published
- 2017
37. Enzymes as Biodevelopers for Nano- And Micropatterned Bicomponent Biopolymer Thin Films
- Author
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Harald Plank, Stefan Spirk, Franz Stelzer, Helmut Schwab, Katrin Niegelhell, Daniel Schwendenwein, Michael Süßenbacher, Thomas Ganner, and Katrin Jammernegg
- Subjects
Materials science ,Polymers and Plastics ,Polyesters ,Hydroxybutyrates ,Bioengineering ,02 engineering and technology ,engineering.material ,010402 general chemistry ,01 natural sciences ,Biomaterials ,chemistry.chemical_compound ,Biopolymers ,Cellulase ,Nano ,Materials Chemistry ,Organic chemistry ,Cellulose ,Thin film ,chemistry.chemical_classification ,Spin coating ,Polymer ,021001 nanoscience & nanotechnology ,Enzymes ,3. Good health ,0104 chemical sciences ,Polyester ,chemistry ,Chemical engineering ,13. Climate action ,engineering ,Biopolymer ,0210 nano-technology ,Science, technology and society ,Carboxylic Ester Hydrolases - Abstract
The creation of nano- and micropatterned polymer films is a crucial step for innumerous applications in science and technology. However, there are several problems associated with environmental aspects concerning the polymer synthesis itself, cross-linkers to induce the patterns as well as toxic solvents used for the preparation and even more important development of the films (e.g., chlorobenzene). In this paper, we present a facile method to produce micro- and nanopatterned biopolymer thin films using enzymes as so-called biodevelopers. Instead of synthetic polymers, naturally derived ones are employed, namely, poly-3-hydroxybutyrate and a cellulose derivative, which are dissolved in a common solvent in different ratios and subjected to spin coating. Consequently, the two biopolymers undergo microphase separation and different domain sizes are formed depending on the ratio of the biopolymers. The development step proceeds via addition of the appropriate enzyme (either PHB-depolymerase or cellulase), whereas one of the two biopolymers is selectively degraded, while the other one remains on the surface. In order to highlight the enzymatic development of the films, video AFM studies have been performed in real time to image the development process in situ as well as surface plasmon resonance spectroscopy to determine the kinetics. These studies may pave the way for the use of enzymes in patterning processes, particularly for materials intended to be used in a physiological environment.
- Published
- 2016
38. Ultrathin Films of Cellulose: A Materials Perspective
- Author
-
Stefan Spirk and Eero Kontturi
- Subjects
Materials science ,Cellulose derivatives ,Nanotechnology ,Review ,02 engineering and technology ,sensors ,010402 general chemistry ,01 natural sciences ,Nanocellulose ,lcsh:Chemistry ,chemistry.chemical_compound ,spin coating ,Deposition (phase transition) ,Cellulose ,Thin film ,nanocellulose ,Spin coating ,cellulose solvents ,General Chemistry ,cellulose derivatives ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Chemistry ,lcsh:QD1-999 ,chemistry ,0210 nano-technology - Abstract
A literature review on ultrathin films of cellulose is presented. The review focuses on different deposition methods of the films – all the way from simple monocomponent films to more elaborate multicomponent structures – and the use of the film structures in the vast realm of materials science. The common approach of utilizing cellulose thin films as experimental models is therefore omitted. The reader will find that modern usage of cellulose thin films constitutes an exciting emerging area within materials science and it goes far beyond the traditional usage of the films as model systems.
- Published
- 2019
39. Synthesis of a tetrazine-quaterthiophene copolymer and its optical, structural and photovoltaic properties
- Author
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Astrid-Caroline, Knall, Sebastian Franz, Hoefler, Manuel, Hollauf, Ferula, Thaler, Sven, Noesberger, Ilie, Hanzu, Heike, Ehmann, Mathias, Hobisch, Stefan, Spirk, Shuguang, Wen, Renqiang, Yang, Thomas, Rath, and Gregor, Trimmel
- Abstract
Herein, we report the synthesis of a novel, tetrazine-based conjugated polymer. Tetrazines have the benefit of being strong electron acceptors, while little steric hindrance is imposed on the flanking thiophene rings. Conversion of a suitably substituted nitrile precursor led to 3,6-bis(5-bromo-4-(2-octyldodecyl)thiophen-2-yl)-1,2,4,5-tetrazine (2OD-TTz). Palladium-catalyzed copolymerization of 2OD-TTz with a bithiophene monomer yielded an alternating tetrazine-quaterthiophene copolymer (PTz4T-2OD). The polymer PTz4T-2OD showed an optical band gap of 1.8 eV, a deep HOMO energy level of - 5.58 eV and good solubility. In combination with the non-fullerene acceptor ITIC-F, solar cells with power conversion efficiencies of up to 2.6% were obtained.
- Published
- 2019
40. Multilayer Density Analysis of Cellulose Thin Films
- Author
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Carina Sampl, Katrin Niegelhell, David Reishofer, Roland Resel, Stefan Spirk, and Ulrich Hirn
- Subjects
Materials science ,02 engineering and technology ,Surface finish ,X-ray reflectivity ,010402 general chemistry ,01 natural sciences ,lcsh:Chemistry ,chemistry.chemical_compound ,Surface plasmon resonance ,Composite material ,Cellulose ,Thin film ,Original Research ,atomic force microscopy ,multilayer analysis ,General Chemistry ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Chemistry ,chemistry ,lcsh:QD1-999 ,0210 nano-technology ,Material properties ,cellulose thin film ,Refractive index ,Layer (electronics) ,surface plasmon resonance - Abstract
An approach for the multilayer density analysis of polysaccharide thin films at the example of cellulose is presented. In detail, a model was developed for the evaluation of the density in different layers across the thickness direction of the film. The cellulose thin film was split into a so called "roughness layer" present at the surface and a "bulk layer" attached to the substrate surface. For this approach, a combination of multi-parameter surface plasmon resonance spectroscopy (SPR) and atomic force microscopy (AFM) was employed to detect changes in the properties, such as cellulose content and density, thickness and refractive index, of the surface near layer and the bulk layer. The surface region of the films featured a much lower density than the bulk. Further, these results correlate to X-ray reflectivity studies, indicating a similar layered structure with reduced density at the surface near regions. The proposed method provides an approach to analyse density variations in thin films which can be used to study material properties and swelling behavior in different layers of the films. Limitations and challenges of the multilayer model evaluation method of cellulose thin films were discussed. This particularly involves the selection of the starting values for iteration of the layer thickness of the top layer, which was overcome by incorporation of AFM data in this study.
- Published
- 2019
41. Biobased Support Layers for the Fractionation and Selective Extraction of Lignosulfonates
- Author
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Stefan Spirk, Armin Zankl, Paul Demmelmayer, Marlene Kienberger, and Michael Weißl
- Subjects
Chromatography ,General Chemical Engineering ,Extraction (chemistry) ,02 engineering and technology ,General Chemistry ,Fractionation ,010403 inorganic & nuclear chemistry ,01 natural sciences ,0104 chemical sciences ,Membrane technology ,chemistry.chemical_compound ,020401 chemical engineering ,chemistry ,Lignosulfonates ,0204 chemical engineering ,Cellulose - Abstract
The paper presents an experimental study on the preparation and characterization of cellulose films and their use for reactive lignosulfonate extraction. The extraction of lignosulfonates leads to emulsion and crud formation when standard equipment is applied. By using cellulose films as a support layer between the aqueous feed phase and the organic extractant phase, emulsion formation is prevented. The results showed that selective separation and a fractionation of the lignosulfonates can be realized with this novel approach simultaneously.
- Published
- 2019
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42. Interactions and Dissociation Constants of Galactomannan Rendered Cellulose Films with Concavalin A by SPR Spectroscopy
- Author
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Fernando Ferreira, Carina Sampl, Mathias Hobisch, Pilar Vilaró, Werner Schlemmer, Michael Weissl, Stefan Spirk, Gundula Marie Teichert, and Luis Alberto Panizzolo
- Subjects
chemistry.chemical_classification ,Polymers and Plastics ,biology ,Communication ,Biomolecule ,Lectin ,General Chemistry ,lectins ,lcsh:QD241-441 ,Dissociation constant ,chemistry.chemical_compound ,Crystallography ,Galactomannan ,Adsorption ,lcsh:Organic chemistry ,chemistry ,galactomannan ,Monolayer ,biology.protein ,Monosaccharide ,Cellulose ,cellulose thin films - Abstract
Interactions of biomolecules at interfaces are important for a variety of physiological processes. Among these, interactions of lectins with monosaccharides have been investigated extensively in the past, while polysaccharide-lectin interactions have scarcely been investigated. Here, we explore the adsorption of galactomannans (GM) extracted from Prosopis affinis on cellulose thin films determined by a combination of multi-parameter surface plasmon resonance spectroscopy (MP-SPR) and atomic force microscopy (AFM). The galactomannan adsorbs spontaneously on the cellulose surfaces forming monolayer type coverage (0.60 ± 0.20 mg·m−2). The interaction of a lectin, Concavalin A (ConA), with these GM rendered cellulose surfaces using MP-SPR has been investigated and the dissociation constant KD (2.1 ± 0.8 × 10−8 M) was determined in a range from 3.4 to 27.3 nM. The experiments revealed that the galactose side chains as well as the mannose reducing end of the GM are weakly interacting with the active sites of the lectins, whereas these interactions are potentially amplified by hydrophobic effects between the non-ionic GM and the lectins, thereby leading to an irreversible adsorption.
- Published
- 2020
43. ESMRMB 2016, 33rd Annual Scientific Meeting, Vienna, AT, September 29 – October 1: Abstracts, Saturday
- Author
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Danuta Kruk, Stefan Spirk, Hermann Scharfetter, Christian Gösweiner, Roland Fischer, Martin Schlögl, and Andreas Petrovic
- Subjects
Nuclear magnetic resonance ,Materials science ,Radiological and Ultrasound Technology ,media_common.quotation_subject ,Quadrupole ,Biophysics ,Contrast (vision) ,Radiology, Nuclear Medicine and imaging ,Pre selection ,Cross relaxation ,media_common - Published
- 2016
44. The chemistry of organo silanetriols
- Author
-
Stefan Spirk and Rudolf Pietschnig
- Subjects
Atomic force microscopy ,Chemistry ,Supramolecular chemistry ,Silanetriol ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Structural chemistry ,0104 chemical sciences ,Inorganic Chemistry ,Materials Chemistry ,Surface modification ,Reactivity (chemistry) ,Physical and Theoretical Chemistry ,0210 nano-technology - Abstract
The chemistry of organo silanetriols is reviewed covering the aspects of synthesis, structural chemistry, reactivity, properties and applications over the last 15 years. Besides relevant progress in established fields like supramolecular chemistry, surface modification and metallasiloxane formation, recent advances include structural investigations in liquid and gaseous states and studies concerning the bio-activity of silanetriols. Based on irreversible condensation starting from silanetriols fascinating cage compounds and cerasomes have been reported as well as silanetriol-modified biopolymers and nanopatterning applications.
- Published
- 2016
45. Topography effects in AFM force mapping experiments on xylan-decorated cellulose thin films
- Author
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Caterina Czibula, Christian Teichert, Christian Ganser, Stefan Spirk, Katrin Niegelhell, Robert Schennach, and Angela Chemelli
- Subjects
Materials science ,Xylan (coating) ,02 engineering and technology ,Adhesion ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Biomaterials ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Microscopy ,Surface roughness ,Surface modification ,Cellulose ,Thin film ,0210 nano-technology ,Deposition (law) - Abstract
Xylan-coated cellulose thin films has been investigated by means of atomic force microscopy (AFM) and force mapping experiments. The birch xylan deposition on the film was performed under control by means of a multiple parameter surface plasmon resonance spectroscopy (MP-SPR) under dynamic conditions. The coated films were submitted to AFM in phase imaging mode to force mapping with modified AFM tips (sensitive to hydrophilic OH and hydrophobic CH3 groups) in order to characterize and localize the xylan on the surfaces. At the first glance, a clear difference in the adhesion force between xylan-coated areas and cellulose has been observed. However, these different adhesion forces originate from topography effects, which prevent an unambiguous identification and subsequent localization of the xylan on the cellulosic surfaces.
- Published
- 2016
46. Adsorption Studies of Organophosphonic Acids on Differently Activated Gold Surfaces
- Author
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Boril Stefanov Chernev, Stefan Spirk, Thomas Grießer, Christian Brandl, Simon Leimgruber, Katrin Niegelhell, Gregor Trimmel, and Robert Schennach
- Subjects
chemistry.chemical_classification ,Inorganic chemistry ,technology, industry, and agriculture ,Analytical chemistry ,Infrared spectroscopy ,02 engineering and technology ,Surfaces and Interfaces ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,Adsorption ,Hydrocarbon ,X-ray photoelectron spectroscopy ,chemistry ,Attenuated total reflection ,Monolayer ,Electrochemistry ,Molecule ,General Materials Science ,Surface plasmon resonance ,0210 nano-technology ,Spectroscopy - Abstract
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.
- Published
- 2016
47. 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
- Subjects
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
48. Supercapacitor Electrodes from Viscose-Based Activated Carbon Fibers: Significant Yield and Performance Improvement Using Diammonium Hydrogen Phosphate as Impregnating Agent
- Author
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Christoph Unterweger, Achim Walter Hassel, Stefan Breitenbach, David Stifter, Mathias Hobisch, Alexander Lumetzberger, Christian Fürst, and Stefan Spirk
- Subjects
Materials science ,02 engineering and technology ,Electrolyte ,010402 general chemistry ,01 natural sciences ,lcsh:QD241-441 ,lcsh:Organic chemistry ,viscose fibers ,bio-based carbon ,Specific surface area ,diammonium hydrogen phosphate ,medicine ,activated carbon ,Viscose ,supercapacitor ,Supercapacitor ,energy storage ,Carbonization ,General Medicine ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Chemical engineering ,Electrode ,Cyclic voltammetry ,0210 nano-technology ,Activated carbon ,medicine.drug - Abstract
Viscose fibers were impregnated with different concentrations of diammonium hydrogen phosphate (DAHP), carbonized, activated, and tested as high-performance electrode materials for supercapacitors. The yield of these activated carbon fibers (ACFs) could be increased by a factor of 14 by using DAHP compared to ACF without impregnation. These specific activation procedures yielded a high specific surface area of more than 2700 m2∙g&minus, 1 with a pore size distribution (PSD) suitable for use as a supercapacitor electrode. The electrode materials were implemented in symmetric supercapacitors using TEMA BF4 as electrolyte and cyclic voltammetry measurements showed high specific capacitances of up to 167 F∙g&minus, 1. Furthermore, the devices showed high energy densities of up to 21.4 W∙h∙kg&minus, 1 and high-power densities of up to 8.7 kW∙kg&minus, 1. The supercapacitors featured high capacity retention (96%) after 10,000 cycles. These results show that ACFs made of viscose fibers, previously impregnated with DAHP, can be used as high-performance electrodes in supercapacitors for energy storage applications.
- Published
- 2020
49. 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
50. Polysaccharides as Battery Components
- Author
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Stefan Spirk
- Published
- 2018
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