Dr. Karl-Heinz Haas | Julius-Maximilians - Universität Würzburg (original) (raw)

Uploads

Papers by Dr. Karl-Heinz Haas

Microporous and Mesoporous Materials, Sep 1, 2000

... allowed to condense. Solutions were formed into thin films on glass plates by sliding a Rakel... more ... allowed to condense. Solutions were formed into thin films on glass plates by sliding a Rakel (“Rakelmesser” from Erichsen; a knife-coating device) containing the solutions over them to limit the thicknesses to 50–90 μm. In some ...

Surface & Coatings Technology, 1999

ABSTRACT Hybrid polymers (ORMOCER®s) with inorganic and organic structural units can be used to g... more ABSTRACT Hybrid polymers (ORMOCER®s) with inorganic and organic structural units can be used to generate new functionalized coatings on a variety of substrates (ceramics, metals, polymers, etc.). By processing at temperatures below 150 °C, the formation of both inorganic and organic network structures using the sol–gel approach is possible.Due to the incorporation of special organic functional groups, important application related properties can be accomplished. ORMOCER® lacquers can be processed by nearly all conventional coating techniques (dipping, spraying, spin on, etc.). The basic application fields for ORMOCER® coatings are:•abrasion and scratch resistance, decoration;•barrier layers for packaging, corrosion resistant layers;•antisoiling, antifogging, antistatic and antireflective applications.In the past two years, the combination of ORMOCER® layers with vapor deposited inorganic thin films (e.g. SiOx) has been investigated, especially for barrier applications. Outstanding barrier properties were achieved, which show synergetic effects by using two different coating techniques together (wet chemical processing, vapor deposition).

Advanced Engineering Materials, Sep 1, 2000

Hybrid materials have found widespread applications in recent years and are one example for the b... more Hybrid materials have found widespread applications in recent years and are one example for the bottom-up approach to nanotechnology: materials and phases are generated by physical or chemical means from precursor compounds forming nanoscale or nanocomposite ...

Elsevier eBooks, 1999

Abstract ORMOCER®s (ORMOCER® Trademark of Fraunhofer-Gesellschaft zur Forderung der angewandten F... more Abstract ORMOCER®s (ORMOCER® Trademark of Fraunhofer-Gesellschaft zur Forderung der angewandten Forschung e.V.) as inorganic-organic polymers synthesized by a two-step sol-gel processing method can be applied as thin transparent coatings on various substrates (polymers, metals, ceramics). The curing of ORMOCER®s is performed thermally (at temperatures below 200°C) or by UV-radiation. Their high abrasion resistance and good chemical stability led to several actual industrial applications. Beside mechanical protection functions (e.g. for sensitive polymer substrates) additional functionalities of ORMOCER® surfaces are investigated to find new application areas. This paper presents two additional surface functions of abrasion resistant ORMOCER® coatings: Antiadhesive and antistatic properties. Incorporation of perfluorinated alkoxysilane compounds via sol-gel processing decreases the surface energy of the cured layer. Water as well as non-polar substances lose their adhesion to the surface, wetting is reduced, solutions are drained off and particles can be removed easily. By addition of polar and/or ionic compounds bearing hydrolyzable alkoxysilyl groups a scratch resistant antistatic coating for polycarbonate was developed. Compared to the uncoated substrate, the specific surface resistance was decreased from 1015 to 108 Ω. Electrostatic charging is decreased and attraction of particles inhibited or reduced. The coatings are abrasion resistant and show very good adhesion even in a wet climate.

Polymer Composites, Aug 5, 2018

Depending on interparticle structure and chemical behavior, fillers greatly influence the mechani... more Depending on interparticle structure and chemical behavior, fillers greatly influence the mechanical properties in rubber compounds. In this work, the influence of the filler-matrix versus filler-filler interaction on the mechanical properties of a silica nanoparticle-rubber composite was investigated. For this purpose, nanostructured microraspberry particles with different surface properties were designed and prepared using colloidal silica and two different kinds of silane agents, one coating agent (triethoxyoctylsilane, OCTEO) and one coupling agent (bis(triethoxysilylpropyl)tetrasulfide, Si69 TM). In addition, the degree of silane coverage of the nanoparticles was adjusted in a precisely controlled way. This sophisticated particle system allowed for straightforward integration into the composite formation process while ensuring that a redispersion of the nanoparticles in the rubber matrix occurred during compounding. With this microraspberry particle system, it was possible to influence the mechanical properties by the degree of silane surface coverage on the nanoparticles while the filler content could be kept constant. The two silane systems were carefully compared and the impact of the particle/particle and the particle/rubber interactions with respect to the mechanical properties of the composite was studied. Ultimately, an overall picture of the influence of the type and the amount of silane on mechanical properties in silica-rubber composites could be obtained.

Encyclopedia of Glass Science, Technology, History, and Culture, 2021

Acta Physica Polonica A, 2009

We examine the influence of a weak non-resonant illumination on the quantum dot photoluminescence... more We examine the influence of a weak non-resonant illumination on the quantum dot photoluminescence spectrum. We observe that even very weak illumination affects both intensity and spectral position of emission lines in the spectrum. We discover no significant asymmetry in spatial dependence and infer that the observed effects cannot be attributed to a single neighbor center.

Bei der Herstellung und beim Einsatz von keramischen Materialien für die Sensorik treten zwei gru... more Bei der Herstellung und beim Einsatz von keramischen Materialien für die Sensorik treten zwei grundlegend verschiedene und unterschiedlich alte Technologien miteinander in Beziehung: Zum einen die schon seit Jahrhunderten prinzipiell bekannte Technik der Herstellung und Aufbereitung von keramischen Materialien und zum anderen die immer wichtiger werdende elektronische beziehungsweise mikroelektronische Technologie zur Erfassung und Weiterverarbeitung von Signalen und Daten

Environmental Nanotechnology, Monitoring & Management

SIGLEAvailable from TIB Hannover: F04B377+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Te... more SIGLEAvailable from TIB Hannover: F04B377+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung und Forschung (BMBF), Bonn (Germany)DEGerman

PURPOSE: To provide a process for producing a composition containing metallic particles having a ... more PURPOSE: To provide a process for producing a composition containing metallic particles having a particle diameter in a nanometer region and being freely applicable by various techniques. CONSTITUTION: There is provided a process for producing a composition containing (A) metallic particles having a mean particle diameter of below 100 nm as calculated as a number-average value and (B) a polymer based on vinyl acetate, vinylamine, vinylimidazole, vinylpyrrolidone, acrylamide, acrylimine, or a mixture thereof, which comprises: reducing metallic particles A and the polymer B dissolved in a solvent with a metal salt in the presence of a solvent; and spray-drying the reaction mixture. COPYRIGHT: (C)1996,JPO

Microporous and Mesoporous Materials, Sep 1, 2000

... allowed to condense. Solutions were formed into thin films on glass plates by sliding a Rakel... more ... allowed to condense. Solutions were formed into thin films on glass plates by sliding a Rakel (“Rakelmesser” from Erichsen; a knife-coating device) containing the solutions over them to limit the thicknesses to 50–90 μm. In some ...

Surface & Coatings Technology, 1999

ABSTRACT Hybrid polymers (ORMOCER®s) with inorganic and organic structural units can be used to g... more ABSTRACT Hybrid polymers (ORMOCER®s) with inorganic and organic structural units can be used to generate new functionalized coatings on a variety of substrates (ceramics, metals, polymers, etc.). By processing at temperatures below 150 °C, the formation of both inorganic and organic network structures using the sol–gel approach is possible.Due to the incorporation of special organic functional groups, important application related properties can be accomplished. ORMOCER® lacquers can be processed by nearly all conventional coating techniques (dipping, spraying, spin on, etc.). The basic application fields for ORMOCER® coatings are:•abrasion and scratch resistance, decoration;•barrier layers for packaging, corrosion resistant layers;•antisoiling, antifogging, antistatic and antireflective applications.In the past two years, the combination of ORMOCER® layers with vapor deposited inorganic thin films (e.g. SiOx) has been investigated, especially for barrier applications. Outstanding barrier properties were achieved, which show synergetic effects by using two different coating techniques together (wet chemical processing, vapor deposition).

Advanced Engineering Materials, Sep 1, 2000

Hybrid materials have found widespread applications in recent years and are one example for the b... more Hybrid materials have found widespread applications in recent years and are one example for the bottom-up approach to nanotechnology: materials and phases are generated by physical or chemical means from precursor compounds forming nanoscale or nanocomposite ...

Elsevier eBooks, 1999

Abstract ORMOCER®s (ORMOCER® Trademark of Fraunhofer-Gesellschaft zur Forderung der angewandten F... more Abstract ORMOCER®s (ORMOCER® Trademark of Fraunhofer-Gesellschaft zur Forderung der angewandten Forschung e.V.) as inorganic-organic polymers synthesized by a two-step sol-gel processing method can be applied as thin transparent coatings on various substrates (polymers, metals, ceramics). The curing of ORMOCER®s is performed thermally (at temperatures below 200°C) or by UV-radiation. Their high abrasion resistance and good chemical stability led to several actual industrial applications. Beside mechanical protection functions (e.g. for sensitive polymer substrates) additional functionalities of ORMOCER® surfaces are investigated to find new application areas. This paper presents two additional surface functions of abrasion resistant ORMOCER® coatings: Antiadhesive and antistatic properties. Incorporation of perfluorinated alkoxysilane compounds via sol-gel processing decreases the surface energy of the cured layer. Water as well as non-polar substances lose their adhesion to the surface, wetting is reduced, solutions are drained off and particles can be removed easily. By addition of polar and/or ionic compounds bearing hydrolyzable alkoxysilyl groups a scratch resistant antistatic coating for polycarbonate was developed. Compared to the uncoated substrate, the specific surface resistance was decreased from 1015 to 108 Ω. Electrostatic charging is decreased and attraction of particles inhibited or reduced. The coatings are abrasion resistant and show very good adhesion even in a wet climate.

Polymer Composites, Aug 5, 2018

Depending on interparticle structure and chemical behavior, fillers greatly influence the mechani... more Depending on interparticle structure and chemical behavior, fillers greatly influence the mechanical properties in rubber compounds. In this work, the influence of the filler-matrix versus filler-filler interaction on the mechanical properties of a silica nanoparticle-rubber composite was investigated. For this purpose, nanostructured microraspberry particles with different surface properties were designed and prepared using colloidal silica and two different kinds of silane agents, one coating agent (triethoxyoctylsilane, OCTEO) and one coupling agent (bis(triethoxysilylpropyl)tetrasulfide, Si69 TM). In addition, the degree of silane coverage of the nanoparticles was adjusted in a precisely controlled way. This sophisticated particle system allowed for straightforward integration into the composite formation process while ensuring that a redispersion of the nanoparticles in the rubber matrix occurred during compounding. With this microraspberry particle system, it was possible to influence the mechanical properties by the degree of silane surface coverage on the nanoparticles while the filler content could be kept constant. The two silane systems were carefully compared and the impact of the particle/particle and the particle/rubber interactions with respect to the mechanical properties of the composite was studied. Ultimately, an overall picture of the influence of the type and the amount of silane on mechanical properties in silica-rubber composites could be obtained.

Encyclopedia of Glass Science, Technology, History, and Culture, 2021

Acta Physica Polonica A, 2009

We examine the influence of a weak non-resonant illumination on the quantum dot photoluminescence... more We examine the influence of a weak non-resonant illumination on the quantum dot photoluminescence spectrum. We observe that even very weak illumination affects both intensity and spectral position of emission lines in the spectrum. We discover no significant asymmetry in spatial dependence and infer that the observed effects cannot be attributed to a single neighbor center.

Bei der Herstellung und beim Einsatz von keramischen Materialien für die Sensorik treten zwei gru... more Bei der Herstellung und beim Einsatz von keramischen Materialien für die Sensorik treten zwei grundlegend verschiedene und unterschiedlich alte Technologien miteinander in Beziehung: Zum einen die schon seit Jahrhunderten prinzipiell bekannte Technik der Herstellung und Aufbereitung von keramischen Materialien und zum anderen die immer wichtiger werdende elektronische beziehungsweise mikroelektronische Technologie zur Erfassung und Weiterverarbeitung von Signalen und Daten

Environmental Nanotechnology, Monitoring & Management

SIGLEAvailable from TIB Hannover: F04B377+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Te... more SIGLEAvailable from TIB Hannover: F04B377+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung und Forschung (BMBF), Bonn (Germany)DEGerman

PURPOSE: To provide a process for producing a composition containing metallic particles having a ... more PURPOSE: To provide a process for producing a composition containing metallic particles having a particle diameter in a nanometer region and being freely applicable by various techniques. CONSTITUTION: There is provided a process for producing a composition containing (A) metallic particles having a mean particle diameter of below 100 nm as calculated as a number-average value and (B) a polymer based on vinyl acetate, vinylamine, vinylimidazole, vinylpyrrolidone, acrylamide, acrylimine, or a mixture thereof, which comprises: reducing metallic particles A and the polymer B dissolved in a solvent with a metal salt in the presence of a solvent; and spray-drying the reaction mixture. COPYRIGHT: (C)1996,JPO