Martin D Hager

Martin D Hager
Friedrich Schiller University Jena | FSU · Institute of Organic Chemistry and Macromolecular Chemistry

Dr.

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249
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10,178
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Publications

Publications (249)
Article
Polymer-based batteries represent a promising concept for next-generation energy storage due to their potentially higher power densities and smaller ecological footprint, compared to classical Li-ion batteries. Since the microstructure of electrodes is a key factor for the performance of battery cells, a detailed understanding of this microstructur...
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Current-voltage (IV) characterization is the most fundamental measurement performed on solar cells. This measurement is commonly used to extract basic solar cell parameters, such as open circuit voltage, short circuit current density, fill factor, and power conversion efficiency. We were able to obtain a fast tool to find defective behavior using S...
Article
Crosslinked hydrophilic poly(2,2,6,6‐tetramethylpiperidinyl‐N‐oxyl‐co‐[2‐(methacryloyloxy)‐ethyl]trimethylammonium chloride) (poly(TEMPO‐co‐METAC)) polymers with different monomer ratios are synthesized and characterized regarding a utilization as electrode material in organic batteries. These polymers can be synthesized rapidly utilizing commercia...
Article
A vast variety of oxidation procedures is known to obtain 2,2,6,6‐tetramethylpiperidinyl‐4‐oxyl (TEMPO) moieties from its piperidinyl precursor. However, up to now no comprehensive study has been performed concerning the performance and feasibility for lab‐scale synthesis. With the focus on the ease of synthesis, occurring impurities, the reaction...
Article
A readily available prototyping process for the fabrication of low-cost microband electrodes is introduced, which are applicable for the accurate amperometric state-of-charge (SOC) measurement in redox flow battery (RFB) electrolytes. For this purpose, an inexpensive and straightforward inkjet printing of conductive platinum-based and insulating po...
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This study presents the synthesis and characterization of metallopolymer networks with a triple shape-memory ability. A covalently crosslinked polymer network featuring two different additional ligands in its side chains is synthesized via free radical polymerization (FRP). The subsequent addition of different metal salts leads to the selective for...
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Aqueous‐organic redox flow batteries (RFBs) have gained considerable interest in recent years, given their potential for an economically viable energy storage at large scale. This, however, strongly depends on both the robustness of the underlying electrolyte chemistry against molecular decomposition reactions as well as the device's operation. Wit...
Article
Polyoxymethylene dimethyl ethers (OMEn) are considered as substituents or additives for fossil Diesel fuel. Efficiency of the synthesis is crucial for the development of industrial scale production plants. Therefore, the design of suitable catalysts and the efficient heating play an important role in OME fuel synthesis. In this work, microwave‐assi...
Article
The TEMPO scaffold is one of the most prominent used posolyte systems in organic redox flow batteries (RFBs). While the aminoxyl radical is well known for his extraordinary stability, there are only a few studies investigating the stability of the respective oxoammonium cation. In this study, we utilize battery experiments to quantify the fade rate...
Article
The volumetric capacities and the lifetime of organic redox flow batteries (RFBs) are strongly dependent on the concentrations of the redox-active molecules in the electrolyte. Single-molecule redox targeting represents an efficient approach toward realizing viable organic RFBs with low to moderate electrolyte concentrations. For the first time, an...
Article
We recently introduced an amperometric, temperature-independent, and calibration-free method for the measurement of the state-of-charge (SOC) of redox flow battery (RFB) electrolytes. In the study at hand, the measurement accuracy of the method is re-evaluated and significantly improved. The absolute root-mean-square deviation (RMSD) is reduced fro...
Article
Trimethylammonium-2,2,6,6-tetramethylpiperidine-1-oxyl chlorid (TMA-TEMPO) has been intensively studied for the usage in aqueous organic redox flow batteries. A straightforward synthesis, a reliable electrochemistry, fast kinetics and high cyc¬ling stability are the...
Chapter
Reversible covalent bonds within polymers/polymer networks aroused the interest of researchers early on and are still of great importance today. Triggering the reversible interaction enables a number of interesting effects and properties. Polymers can be decrosslinked or can decompose on request. Particularly, self-healing polymers based on reversi...
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In this work, we report the synthesis and characterization of a compact, ferrocene tetramer and a linear viologen polymer. The latter material is a new, 4,4′-bipyridine containing, organo-soluble polymer. As we aimed for solubility in nonpolar solvents, a 2-ethylhexyl-moiety to promote organosolubility and 4-vinylbenzyl serving as a polymerizable g...
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A new sulfamidic acid anthraquinone derivative was synthesized from 2,6-diaminoanthraquinone with high yields, designed for utilization in redox flow batteries. The active material was investigated with cyclic voltammetry, revealing a reversible redox reaction at approximately -0.65 V vs. Ag/AgCl at pH-values above 12. A stress test in a redox flow...
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This study presents the first liquid chromatography method for the quantitative and qualitative analysis of highly reactive oxoammonium cations based on a simple derivatization reaction. Rapid 1,2-electrophilic addition reactions with olefins were used to transform these reactive species into analyzable derivates. Three model substances were chosen...
Article
Renewable organic batteries represent a valuable option to store sustainably generated energy and can play a major role in phasing out current carbon-based energy production. Several approaches have emerged over the last 80 years that utilize organic redox materials as active components in batteries. In particular, polymers have gained considerable...
Article
It is common knowledge that molecular energy level offsets of a type II heterojunction formed at the donor–acceptor interface are considered to be the driving force for photoinduced charge transfer in organic solar cells. Usually, these offsets – present between molecular energy levels of the donor and acceptor – are obtained via cyclic voltammetry...
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The self-healing behavior of two supramolecular polymers based on π–π-interactions featuring different polymer backbones is presented. For this purpose, these polymers were synthesized utilizing a polycondensation of a perylene tetracarboxylic dianhydride with polyether-based diamines and the resulting materials were investigated using various anal...
Article
Selective complexation of metal ions represents a powerful tool for the development of versatile supramolecular architectures. While research in the field of molecular devices and machinery is sophisticated, the selective formation of metal complexes is not prevalent in polymer chemistry. Thus, the implementation of orthogonal binding concepts into...
Article
We report a novel hole conductive polymer with photoactive Os(ii) complexes in the side chains. This PPV derivative can be activated upon absorption of red visible light and delivers notable photocurrents when used as photocathode material. Thus, the polymer presents as a stepping stone towards developing soft matter alternatives to NiO photocathod...
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Full-text available
Selective complexation of metal ions represents a powerful tool for the development of versatile supramolecular architectures. While research in the field of molecular devices and machinery is sophisticated, the selective formation of metal complexes is not prevalent in polymer chemistry. Thus, the implementation of orthogonal binding concepts into...
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Full-text available
The embedding of molecular reactive species such as catalysts into polymers opens up new avenues for advanced composite design for energy technologies and beyond. Herein, two new approaches for the connection of molecular molybdenum sulfide clusters and synthetic polymers are presented. The approach one is based on the utilization of a molecular mo...
Article
This work presents the synthesis and characterization of easily tuneable shape-memory metallopolymers. Furthermore, the structural design enables excellent rewriting properties. For this purpose, two different polymers were synthesized using either 2-ethyl hexyl- or butyl methacrylate monomers featuring both histidine and terpyridine ligands in the...
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The halogen bond is a special non-covalent interaction, which can represent a powerful tool in supramolecular chemistry. Although the halogen bond offers several advantages compared to the related hydrogen bond, it is currently still underrepresented in polymer science. The structural related hydrogen bonding assumes a leading position in polymer m...
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Owing to their broad range of redox potential, quinones/hydroquinones can be utilized for energy storage in redox flow batteries. In terms of stability, organic catholytes are more challenging than anolytes. The two-electron transfer feature adds value when building all-quinone flow battery systems. However, the dimerization of quinones/hydroquinon...
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The transition from fossil to renewable energy sources requires adequate storage technologies due to the intermittency of the supplied energy. With respect to this, organic redox-flow batteries (ORFBs) represent a promising concept for the storage of electricity on a large scale at economically justifiable costs. However, these storage technologies...
Article
The scratch healing behavior of different polymers based on reversible interactions was investigated. For this purpose, scratches were induced via femtosecond laser ablation and were analyzed using laser-scanning microscopy. The healing process was monitored over time and the residual scratch volume was studied. Thus, healing kinetics of different...
Article
The incorporation of metal complexes into polymers leads to functional materials; whereas, the properties of polymers – easy processability, light weight or the adjustable molar mass – and those of metal complexes – optical properties, catalytic activity or biomedical potential – can be combined. Through the years, various different applications ha...
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Flexible cross-linked anion exchange membranes (AEMs) based on poly (p-phenylene oxide) grafted with N-spirocyclic quaternary ammonium cations were synthesized via UV-induced free-radical polymerization by using diallylpiperidinium chloride as an ionic monomer. Five membranes with ion exchange capacity (IEC) varying between 1.5 to 2.8 mmol Cl−·g−1...
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Shape‐memory polymers (SMPs) are well investigated smart materials. With their ability to memorize their original shape they are interesting candidates for a large range of applications. Certain SMPs feature triple shape‐memory behavior. In these cases, it is possible to fix two different temporary shapes. However, the exact quantification of the i...
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In article number 2000636 by Martin D. Hager and co‐workers, novel biobased intelligent ionomers are presented. Itaconic acid derivates are utilized to synthesize different ionomers capable of self‐healing. The thermal and mechanic properties are investigated in detail utilizing differential scanning calorimetry, thermo gravimetric analysis, FT‐Ram...
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A new shape‐memory polymer is presented, in which both the stable phase as well as the switching unit consist of two different metal complexes. Suitable metal ions, which simultaneously form labile complexes with histidine and stable ones with terpyridine ligands, are identified via isothermal titration calorimetry (ITC) measurements. Different cop...
Article
Flow Batteries (FBs) currently are one of the most promising large-scale energy storage technologies for energy grids with a large share of renewable electricity generation. Among the main technological challenges for the economic operation of a large-scale battery technology is its calendar lifetime, which has to cover a few decades without signif...
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A conductive polymer (poly( p -phenylenevinylene), PPV ) was covalently modified with Ru II complexes to develop an all-polymer photocathode as a conceptual alternative to dye-sensitized NiO, which is the current state-of-the-art photocathode in solar fuels research. Photocathodes require efficient light-induced charge-transfer processes and we inv...
Article
A new monomer, the 2-ferrocene-ethyl-2-oxazoline, was copoly-merized with 2-alkyl-2-oxazolines. The cationic ring opening polymerization (CROP) of 2-oxazolines allows the synthesis of well-defined copolymers with adjustable molar masses as well as...
Chapter
Polymeric redox flow batteries are based on redox-active polymers as active compounds. These materials can be used in solution, as polymeric assemblies as well as dispersions. Due to the size of the molecules, size exclusion membranes can be utilized in contrast to the common proton-conducting membranes as well as ion-selective membranes. The rich...
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This article presents novel biobased ionomers featuring self‐healing abilities. These smart materials are synthesized from itaconic acid derivates. Large quantities of itaconic acid can be produced from diverse biomass like corn, rice, and others. This study presents a comprehensive investigation of their thermal and mechanical properties via diffe...
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Polymers: Materials that pull themselves together A novel soft material that can heal itself has been engineered by researchers in Germany. Polymeric molecules are formed by long chains of atoms. Some polymers can reform when broken, giving them the intrinsic ability to repair scratches or tears. These self-healing properties are useful for applica...
Article
In article number 2001825 Ulrich S. Schubert and co‐workers present the first high‐temperature stable polymer for Redox‐Flow‐Batteries (RFB), enabling applications in connection with solar and wind parks in warm environments without cooling the battery (up to 60 °C). This will significantly contribute to a future energy transition with a reduced CO...
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Batteries have become an integral part of everyday life—from small coin cells to batteries for mobile phones, as well as batteries for electric vehicles and an increasing number of stationary energy storage applications. There is a large variety of standardized battery sizes (e.g., the familiar AA‐battery or AAA‐battery). Interestingly, all these b...
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Water‐soluble, and ferrocene‐containing methacrylamide copolymers with different comonomer ratios of the solubility‐promoting comonomer [2‐(methacryloyloxy)‐ethyl]‐trimethylammonium chloride (METAC) are synthesized in order to obtain a novel, temperature‐stable electrolyte for aqueous redox flow batteries. The electrochemical properties of one chos...
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Die Kombination von DNA‐Origami mit synthetischen Polymeren führt zu einer neuen Klasse von Materialien mit interessanten Eigenschaften und Merkmalen. Dieses Verfahren ist genauer als herkömmliche Nanofabrikationsverfahren, wie die Positionierung einzelner Polymerstränge. In diesem Kurzaufsatz fassen wir die mögliche Herstellung von Nanostrukturen...
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While the art of DNA origami has been investigated extensively in recent years and demonstrated to work in a reliable manner, precise engineering of such patterns with polymers represents an emerging topic. Compared to conventional top‐down approaches ( i.e. lithography) or bottom‐up functionalization tech­niques ( i.e. self‐assembly), the com­bina...
Article
Self-healing polymers based on the novel damage management concept were introduced several years ago. Since then different concepts have been successfully developed. However, the analysis and characterization of the self-healing process represents still a significant challenge, in particular for the quantification of scratch healing. Consequently,...
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Metallopolymers represent an interesting combination of inorganic metal complexes and polymers resulting in a variety of outstanding properties and applications. One field of interest are stimuli-responsive materials and, in particular, self-healing polymers. These systems could be achieved by the incorporation of terpyridine–lanthanoid complexes o...
Article
Fluorescence upconversion by triplet-triplet annihilation is demonstrated for a fully polymer-integrated material, i.e. in the limit of restricted diffusion. Organic sensitizer and acceptor are covalently attached to a poly(methacrylate) backbone, yielding a metal-free macromolecular all-in-one system for fluorescence upconversion. Due to the spati...
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The mechanical addressability of specific chemical bonds holds a high potential for the improvement of polymeric materials. While in many cases, mechanical forces applied to polymers lead to bond scissoring and materials failure, including mechanophores into the polymer structure can lead to stimuli-responsive materials reacting to an applied force...
Chapter
Self-healing polymers look back on almost 40 years of history. Beginning in the early 1980s, many different examples were studied—for instance, the self-healing polymers based on microcapsules in 2001. These materials were able to close cracks, to heal damage, and to restore their (mechanical) properties almost like the big role model: nature. The...
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Shape memory polymers represent an interesting class of stimuli-responsive polymers. With their ability to memorize and recover their original shape, they could be useful in almost every area of our daily life. We herein present the synthesis of shape-memory metallopolymers in which the switching unit is designed by using bis(pyridine–triazole) met...
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For this paper, the self-healing ability of poly(methacrylate)s crosslinked via reversible urea bonds was studied in detail. In this context, the effects of healing time and temperature on the healing process were investigated. Furthermore, the impact of the size of the damage (i.e., area of the scratch) was monitored. Aging processes, counteractin...
Article
We report a cooperative study conducted between different laboratories to investigate organic solar cell degradation with respect to P3HT material properties and different solar cell architectures. Various batches of P3HT were collected from different suppliers reflecting commercial availability as well as properties variability. Among the material...
Article
Herein, we present a novel copolymer (1), which incorporates 2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) as redox-active compound and the zwitterionic [2-(methacryl-oxy)ethyl)dimethyl-(3-sulfopropyl)]ammonium hydroxide as a solubilizing comonomer, for the application as catholyte species within aqueous redox flow batteries (RFBs). The presented...
Article
A simple mathematical framework for a calibration-free real-time state-of-charge (SOC) monitoring of redox flow battery (RFB) electrolytes, which is based on mass-transfer limited amperometry, is theoretically derived. The equations are initially validated with literature data for a vanadium-based RFB electrolyte revealing absolute root-mean-square...
Chapter
The self-healing phenomenon is well-known from nature. Since the last 15 years, several approaches were developed in order to transfer this behavior into synthetic materials and to enable the preparation of multifunctional polymers. The following chapter summarizes the different polymers and their corresponding healing mechanism and provides an ove...
Article
A method for the real-time monitoring of the state-of-charge of redox flow batteries is presented, which provides half-cell resolution. The well-known standard procedure for the state-of-charge monitoring, which utilizes the equilibrium potential of the monitored electrolyte versus a standard reference electrode in an open-circuit cell, is modified...
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Biology offers a valuable inspiration toward the development of self-healing engineering composites and polymers. In particular, chemical level design principles extracted from proteinaceous biopolymers, especially the mussel byssus, provide inspiration for design of autonomous and intrinsic healing in synthetic polymers. The mussel byssus is an ac...
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In this issue of Joule, Liu and coworkers present the use of the well-known ferrocyanide complex as an active electrode material for an aqueous organic/organometallic redox flow battery. The ammonium cation was used as counter cation in place of the former-utilized sodium and potassium ions. Interestingly, by this simple cation exchange, remarkable...