Rudolf Kiefer - Academia.edu (original) (raw)

Papers by Rudolf Kiefer

Research paper thumbnail of Dual function composite fibers of cellulose with activated carbon aerogel and carbide derived carbon

Journal of Applied Polymer Science, 2022

Research paper thumbnail of Dual function composite fibers of cellulose with activated carbon aerogel and carbide derived carbon

Journal of Applied Polymer Science, 2022

Research paper thumbnail of Polypyrrole Polyethylene Composite for Controllable Linear Actuators in Different Organic Electrolytes

Research paper thumbnail of Hybrid Electrolyte Based on PEO and Ionic Liquid with In Situ Produced and Dispersed Silica for Sustainable Solid-State Battery

Sustainability, Feb 19, 2024

Research paper thumbnail of Robotic Fish Based on a Polymer Actuator

Research paper thumbnail of Production of Novel Bio-Flocculants from <i>Klebsiella variicola</i> BF1 using Cassava Starch Wastewater and its Application

Current Science, Jul 10, 2019

Research paper thumbnail of Poly(ethylene oxide) in polypyrrole doped dodecylbenzenesulfonate: characterisation and linear actuation

International Journal of Nanotechnology, 2018

Research paper thumbnail of Cardiovascular Disease and Possible Ways in Which Lycopene Acts as an Efficient Cardio-Protectant against Different Cardiovascular Risk Factors

Molecules, May 18, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Research paper thumbnail of Prognostic and Clinical Implications of UNC13C expression in Hepatocellular Carcinoma Patients

International Journal of Medical Sciences, 2023

Research paper thumbnail of Electrochemical performance of composite electrodes based on rGO, Mn/Cu metal–organic frameworks, and PANI

Scientific Reports, Jan 13, 2022

Research paper thumbnail of Polypyrrole with Embedded Carbide-Derived Carbon with and without Phosphor Tungsten Acid: Linear Actuation and Energy Storage

Research paper thumbnail of Sustainability of Multiwall Carbon Nanotube Fibers and Their Cellulose Composite

Sustainability

Nowadays, the research community envisions smart materials composed of biodegradable, biocompatib... more Nowadays, the research community envisions smart materials composed of biodegradable, biocompatible, and sustainable natural polymers, such as cellulose. Most applications of cellulose electroactive materials are developed for energy storage and sensors, while only a few are reported for linear actuators. Therefore, we introduce here cellulose-multiwall carbon nanotube composite (Cell-CNT) fibers compared with pristine multiwall carbon nanotube (CNT) fibers made by dielectrophoresis (DEP) in their linear actuation in an organic electrolyte. Electrochemical measurements (cyclic voltammetry, square wave potential steps, and chronopotentiometry) were performed with electromechanical deformation (EMD) measurements. The linear actuation of Cell-CNT outperformed the main actuation at discharging, having 7.9 kPa stress and 0.062% strain, making this composite more sustainable in smart materials, textiles, or robotics. The CNT fiber depends on scan rates switching from mixed actuation to ma...

Research paper thumbnail of Electrolyte contribution to the multifunctional response of cellulose carbon nanotube fibers

Reactive and Functional Polymers

Research paper thumbnail of Role of Polyoxometalate Contents in Polypyrrole: Linear Actuation and Energy Storage

Materials, May 18, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Research paper thumbnail of Polypyrrole/carbide-derived carbon composite in organic electrolyte: Characterization as a linear actuator

Reactive & Functional Polymers, Oct 1, 2018

Research paper thumbnail of Concept of an artificial muscle design on polypyrrole nanofiber scaffolds

PLOS ONE, May 11, 2020

Here we present the synthesis and characterization of two new conducting materials having a high ... more Here we present the synthesis and characterization of two new conducting materials having a high electro-chemo-mechanical activity for possible applications as artificial muscles or soft smart actuators in biomimetic structures. Glucose-gelatin nanofiber scaffolds (CFS) were coated with polypyrrole (PPy) first by chemical polymerization followed by electrochemical polymerization doped with dodecylbenzensulfonate (DBS-) forming CFS-PPy/ DBS films, or with trifluoromethanesulfonate (CF 3 SO 3-, TF) giving CFS-PPy/TF films. The composition, electronic and ionic conductivity of the materials were determined using different techniques. The electro-chemo-mechanical characterization of the films was carried out by cyclic voltammetry and square wave potential steps in bis(trifluoromethane)sulfonimide lithium solutions of propylene carbonate (LiTFSI-PC). Linear actuation of the CFS-PPy/DBS material exhibited 20% of strain variation with a stress of 0.14 MPa, rather similar to skeletal muscles. After 1000 cycles, the creeping effect was as low as 0,2% having a good long-term stability showing a strain variation per cycle of-1.8% (after 1000 cycles). Those material properties are excellent for future technological applications as artificial muscles, batteries, smart membranes, and so on.

Research paper thumbnail of Embedded Carbide-derived Carbon (CDC) particles in polypyrrole (PPy) for linear actuator

Proceedings of SPIE, Apr 15, 2016

Conducting polymer linear actuators, for example sodium dodecylbenzenesulfonate (NaDBS) doped pol... more Conducting polymer linear actuators, for example sodium dodecylbenzenesulfonate (NaDBS) doped polypyrrole (PPy/DBS), have shown moderate strain and stress. The goal of this work was to increase the obtainable strain and stress by adding additional active material to PPy/DBS. In recent year’s carbide-derived carbon (CDC)-based materials have been applied in actuators; however, the obtained displacement and actuation speed has been low comparing to conducting polymer based actuators. In the present work, a CDC-PPy hybrid was synthesized electrochemically and polyoxometalate (POM) – phosphotungstic acid – was used to attach charge to CDC particles. The CDC-POM served in the presence of NaDBS as an additional electrolyte. Cyclic voltammetry and chronopotentiometric electrochemomechanical deformation (ECMD) measurements were performed in Lithium bis(trifluoromethanesulfonyl)- imide (LiTFSI) aqueous electrolyte. The ECMD measurements revealed that the hybrid CDC-PPy material exhibited higher force and strain in comparison to PPy/DBS films. The new material was investigated by scanning electron microscopy (SEM) to evaluate CDC particle embedding in the polymer network.

Research paper thumbnail of Modified Back Projection Kernel Based Image Super Resolution

Research paper thumbnail of Electrochemomechanical deformation (ECMD) of PPyDBS in free standing film formation and trilayer designs

Proceedings of SPIE, Mar 8, 2014

ABSTRACT An investigation is reported into the electrochemomechanical deformation (ECMD) of polyp... more ABSTRACT An investigation is reported into the electrochemomechanical deformation (ECMD) of polypyrrole (PPy) doped with dodecylbenzenesulfonate (DBS) in the form of freestanding films and deposited onto conductive substrates (chemically fixed poly-3,4-(ethylenedioxythiophene, PEDOT) based on PVdF (poly(vinylidenefluoride)). Linear actuation has been achieved starting from a trilayer bending actuator design with a stretchable middle layer. To allow evaluation of the proposed design, commercially available PVdF membranes were chosen as model material. For bending trilayer functionality, electronic separation of both electrode layers is essential, but in order to obtain linear actuation, the CP layers on either side are connected to form a single working electrode. The PPyDBS free standing films and PPyDBS deposited on PEDOT-PVdF-PEDOT were investigated by electrochemical methods (cyclic voltammetry, square wave potentials) in a 4-methyl-1,3-dioxolan-2-one (propylene carbonate, PC) solution of tetrabutylammonium trifluoromethanesulfonate (TBACF3SO3). This study also presents a novel method of utilizing scanning ion-conductance microscopy (SICM) to accurately examine the electrochemical redox behavior of the surface layer of the linear actuator using a micropipette tip.

Research paper thumbnail of Mechanical and electro-mechanical properties of EAP actuators with inkjet printed electrodes

Synthetic Metals, Dec 1, 2018

Abstract Electrically conductive polymer (CP) based ionic electromechanically active polymer comp... more Abstract Electrically conductive polymer (CP) based ionic electromechanically active polymer composites (IEAP-s) are attractive as bending and linear actuators in compliant and miniature devices due to low operating voltage. Ink-jet printing is a promising technology for fabrication of microscale CP-based IEAP-s with customized shapes and geometries. The current study investigates tailoring of the mechanical and electromechanical properties of the actuators by controlled growth of ink-jet printed poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS) based electrodes on commercial poly(vinylidene fluoride) (PVdF) membranes. In parallel with PEDOT:PSS, hybrid actuators with ink-jet printed PEDOT:PSS and activated carbon aerogel electrodes were investigated. Cumulative growth of electrodes with each deposited layer was achieved in the case of both electrode materials. The strain, blocking force and capacitance of the actuators were in linear correlation with the thickness of the electrodes. Simple method of control encourages implementation of ink-jet-printing technology for manufacturing of IEAP micro-actuators with desired mechanical and electromechanical properties.

Research paper thumbnail of Dual function composite fibers of cellulose with activated carbon aerogel and carbide derived carbon

Journal of Applied Polymer Science, 2022

Research paper thumbnail of Dual function composite fibers of cellulose with activated carbon aerogel and carbide derived carbon

Journal of Applied Polymer Science, 2022

Research paper thumbnail of Polypyrrole Polyethylene Composite for Controllable Linear Actuators in Different Organic Electrolytes

Research paper thumbnail of Hybrid Electrolyte Based on PEO and Ionic Liquid with In Situ Produced and Dispersed Silica for Sustainable Solid-State Battery

Sustainability, Feb 19, 2024

Research paper thumbnail of Robotic Fish Based on a Polymer Actuator

Research paper thumbnail of Production of Novel Bio-Flocculants from <i>Klebsiella variicola</i> BF1 using Cassava Starch Wastewater and its Application

Current Science, Jul 10, 2019

Research paper thumbnail of Poly(ethylene oxide) in polypyrrole doped dodecylbenzenesulfonate: characterisation and linear actuation

International Journal of Nanotechnology, 2018

Research paper thumbnail of Cardiovascular Disease and Possible Ways in Which Lycopene Acts as an Efficient Cardio-Protectant against Different Cardiovascular Risk Factors

Molecules, May 18, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Research paper thumbnail of Prognostic and Clinical Implications of UNC13C expression in Hepatocellular Carcinoma Patients

International Journal of Medical Sciences, 2023

Research paper thumbnail of Electrochemical performance of composite electrodes based on rGO, Mn/Cu metal–organic frameworks, and PANI

Scientific Reports, Jan 13, 2022

Research paper thumbnail of Polypyrrole with Embedded Carbide-Derived Carbon with and without Phosphor Tungsten Acid: Linear Actuation and Energy Storage

Research paper thumbnail of Sustainability of Multiwall Carbon Nanotube Fibers and Their Cellulose Composite

Sustainability

Nowadays, the research community envisions smart materials composed of biodegradable, biocompatib... more Nowadays, the research community envisions smart materials composed of biodegradable, biocompatible, and sustainable natural polymers, such as cellulose. Most applications of cellulose electroactive materials are developed for energy storage and sensors, while only a few are reported for linear actuators. Therefore, we introduce here cellulose-multiwall carbon nanotube composite (Cell-CNT) fibers compared with pristine multiwall carbon nanotube (CNT) fibers made by dielectrophoresis (DEP) in their linear actuation in an organic electrolyte. Electrochemical measurements (cyclic voltammetry, square wave potential steps, and chronopotentiometry) were performed with electromechanical deformation (EMD) measurements. The linear actuation of Cell-CNT outperformed the main actuation at discharging, having 7.9 kPa stress and 0.062% strain, making this composite more sustainable in smart materials, textiles, or robotics. The CNT fiber depends on scan rates switching from mixed actuation to ma...

Research paper thumbnail of Electrolyte contribution to the multifunctional response of cellulose carbon nanotube fibers

Reactive and Functional Polymers

Research paper thumbnail of Role of Polyoxometalate Contents in Polypyrrole: Linear Actuation and Energy Storage

Materials, May 18, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Research paper thumbnail of Polypyrrole/carbide-derived carbon composite in organic electrolyte: Characterization as a linear actuator

Reactive & Functional Polymers, Oct 1, 2018

Research paper thumbnail of Concept of an artificial muscle design on polypyrrole nanofiber scaffolds

PLOS ONE, May 11, 2020

Here we present the synthesis and characterization of two new conducting materials having a high ... more Here we present the synthesis and characterization of two new conducting materials having a high electro-chemo-mechanical activity for possible applications as artificial muscles or soft smart actuators in biomimetic structures. Glucose-gelatin nanofiber scaffolds (CFS) were coated with polypyrrole (PPy) first by chemical polymerization followed by electrochemical polymerization doped with dodecylbenzensulfonate (DBS-) forming CFS-PPy/ DBS films, or with trifluoromethanesulfonate (CF 3 SO 3-, TF) giving CFS-PPy/TF films. The composition, electronic and ionic conductivity of the materials were determined using different techniques. The electro-chemo-mechanical characterization of the films was carried out by cyclic voltammetry and square wave potential steps in bis(trifluoromethane)sulfonimide lithium solutions of propylene carbonate (LiTFSI-PC). Linear actuation of the CFS-PPy/DBS material exhibited 20% of strain variation with a stress of 0.14 MPa, rather similar to skeletal muscles. After 1000 cycles, the creeping effect was as low as 0,2% having a good long-term stability showing a strain variation per cycle of-1.8% (after 1000 cycles). Those material properties are excellent for future technological applications as artificial muscles, batteries, smart membranes, and so on.

Research paper thumbnail of Embedded Carbide-derived Carbon (CDC) particles in polypyrrole (PPy) for linear actuator

Proceedings of SPIE, Apr 15, 2016

Conducting polymer linear actuators, for example sodium dodecylbenzenesulfonate (NaDBS) doped pol... more Conducting polymer linear actuators, for example sodium dodecylbenzenesulfonate (NaDBS) doped polypyrrole (PPy/DBS), have shown moderate strain and stress. The goal of this work was to increase the obtainable strain and stress by adding additional active material to PPy/DBS. In recent year’s carbide-derived carbon (CDC)-based materials have been applied in actuators; however, the obtained displacement and actuation speed has been low comparing to conducting polymer based actuators. In the present work, a CDC-PPy hybrid was synthesized electrochemically and polyoxometalate (POM) – phosphotungstic acid – was used to attach charge to CDC particles. The CDC-POM served in the presence of NaDBS as an additional electrolyte. Cyclic voltammetry and chronopotentiometric electrochemomechanical deformation (ECMD) measurements were performed in Lithium bis(trifluoromethanesulfonyl)- imide (LiTFSI) aqueous electrolyte. The ECMD measurements revealed that the hybrid CDC-PPy material exhibited higher force and strain in comparison to PPy/DBS films. The new material was investigated by scanning electron microscopy (SEM) to evaluate CDC particle embedding in the polymer network.

Research paper thumbnail of Modified Back Projection Kernel Based Image Super Resolution

Research paper thumbnail of Electrochemomechanical deformation (ECMD) of PPyDBS in free standing film formation and trilayer designs

Proceedings of SPIE, Mar 8, 2014

ABSTRACT An investigation is reported into the electrochemomechanical deformation (ECMD) of polyp... more ABSTRACT An investigation is reported into the electrochemomechanical deformation (ECMD) of polypyrrole (PPy) doped with dodecylbenzenesulfonate (DBS) in the form of freestanding films and deposited onto conductive substrates (chemically fixed poly-3,4-(ethylenedioxythiophene, PEDOT) based on PVdF (poly(vinylidenefluoride)). Linear actuation has been achieved starting from a trilayer bending actuator design with a stretchable middle layer. To allow evaluation of the proposed design, commercially available PVdF membranes were chosen as model material. For bending trilayer functionality, electronic separation of both electrode layers is essential, but in order to obtain linear actuation, the CP layers on either side are connected to form a single working electrode. The PPyDBS free standing films and PPyDBS deposited on PEDOT-PVdF-PEDOT were investigated by electrochemical methods (cyclic voltammetry, square wave potentials) in a 4-methyl-1,3-dioxolan-2-one (propylene carbonate, PC) solution of tetrabutylammonium trifluoromethanesulfonate (TBACF3SO3). This study also presents a novel method of utilizing scanning ion-conductance microscopy (SICM) to accurately examine the electrochemical redox behavior of the surface layer of the linear actuator using a micropipette tip.

Research paper thumbnail of Mechanical and electro-mechanical properties of EAP actuators with inkjet printed electrodes

Synthetic Metals, Dec 1, 2018

Abstract Electrically conductive polymer (CP) based ionic electromechanically active polymer comp... more Abstract Electrically conductive polymer (CP) based ionic electromechanically active polymer composites (IEAP-s) are attractive as bending and linear actuators in compliant and miniature devices due to low operating voltage. Ink-jet printing is a promising technology for fabrication of microscale CP-based IEAP-s with customized shapes and geometries. The current study investigates tailoring of the mechanical and electromechanical properties of the actuators by controlled growth of ink-jet printed poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS) based electrodes on commercial poly(vinylidene fluoride) (PVdF) membranes. In parallel with PEDOT:PSS, hybrid actuators with ink-jet printed PEDOT:PSS and activated carbon aerogel electrodes were investigated. Cumulative growth of electrodes with each deposited layer was achieved in the case of both electrode materials. The strain, blocking force and capacitance of the actuators were in linear correlation with the thickness of the electrodes. Simple method of control encourages implementation of ink-jet-printing technology for manufacturing of IEAP micro-actuators with desired mechanical and electromechanical properties.