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6. Investigating volume change and ion transport in conjugated polymers

Author

Gladisch, Johannes

Subjects
Polymerkemi, sense organs, Polymer Chemistry
Abstract

Volume changes are the foundation for a wide range of phenomena and applications, ranging from the movement of plants to valves and drug delivery devices. Therefore, it does not come as a surprise that controlled volume changes are an interesting topic of research. In this thesis, volume changes in polymers are the object of investigation. Polymers are a class of macromolecules that comprise repetitive units. Owing to the wide variety of such units, polymers can exhibit manifold properties, including but not limited to strong water attraction and electrical conductivity. The former is the defining property in polymer hydrogels while the latter is a core property of conducting polymers. Both the water attracting properties and conductivity are closely linked to transport events on a molecular level. In the case of hydrogels, it is predominantly water uptake, while in the case of conducting polymers it is a complex interplay between charges, ionic charge balancing entities and water. However, in either case the transport events lead to volume changes. Despite the similarities, the properties of the materials differ greatly. On the one hand volume changes in hydrogels are very large but hard to control. On the other hand, volume changes in conducting polymers are much smaller than in hydrogels, but the control is easier due to the electronic addressing. P(gXTX) polymers combine a conducting polymer backbone with hydrogel sidechains. As described in publication 1, this combination of molecular entities was found to enabled unique properties of an electrically controllable giant volume change and concomitant solid-gel transition. In the second publication, the effect of the side chain lengths on the volume change properties of the polymers were explored. The knowledge acquired from these studies helped us to develop an electroactive filter based on p(gXTX) polymers which enabled electrochemical modulation of flow (publication 3). The aim of the fourth publication was to study the complex electronic-ionic transport processes and volume changes in a model conducting polymer, PEDOT:Tos. The understanding of fundamental processes and properties of controllable volume changes may pave the way for advances in various applications, including electroactive meshes, actuators and drug delivery devices.

Published
2021

9. Controlling Electrochemically Induced Volume Changes in Conjugated Polymers by Chemical Design: from Theory to Devices

Author

Moser, Maximilian, primary, Gladisch, Johannes, additional, Ghosh, Sarbani, additional, Hidalgo, Tania Cecilia, additional, Ponder, James F., additional, Sheelamanthula, Rajendar, additional, Thiburce, Quentin, additional, Gasparini, Nicola, additional, Wadsworth, Andrew, additional, Salleo, Alberto, additional, Inal, Sahika, additional, Berggren, Magnus, additional, Zozoulenko, Igor, additional, Stavrinidou, Eleni, additional, and McCulloch, Iain, additional

Published
2021
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10. Toughening of a Soft Polar Polythiophene through Copolymerization with Hard Urethane Segments

Author

Zokaei, Sepideh, primary, Kroon, Renee, additional, Gladisch, Johannes, additional, Paulsen, Bryan D., additional, Sohn, Wonil, additional, Hofmann, Anna I., additional, Persson, Gustav, additional, Stamm, Arne, additional, Syrén, Per‐Olof, additional, Olsson, Eva, additional, Rivnay, Jonathan, additional, Stavrinidou, Eleni, additional, Lund, Anja, additional, and Müller, Christian, additional

Published
2020
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11. Side Chain Redistribution as a Strategy to Boost Organic Electrochemical Transistor Performance and Stability

Author

Moser, Maximilian, primary, Hidalgo, Tania Cecilia, additional, Surgailis, Jokubas, additional, Gladisch, Johannes, additional, Ghosh, Sarbani, additional, Sheelamanthula, Rajendar, additional, Thiburce, Quentin, additional, Giovannitti, Alexander, additional, Salleo, Alberto, additional, Gasparini, Nicola, additional, Wadsworth, Andrew, additional, Zozoulenko, Igor, additional, Berggren, Magnus, additional, Stavrinidou, Eleni, additional, Inal, Sahika, additional, and McCulloch, Iain, additional

Published
2020
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15. Toughening of a Soft Polar Polythiophene through Copolymerization with Hard Urethane Segments.

Author

Zokaei, Sepideh, Kroon, Renee, Gladisch, Johannes, Paulsen, Bryan D., Sohn, Wonil, Hofmann, Anna I., Persson, Gustav, Stamm, Arne, Syrén, Per‐Olof, Olsson, Eva, Rivnay, Jonathan, Stavrinidou, Eleni, Lund, Anja, and Müller, Christian

Subjects
URETHANE, POLYTHIOPHENES, POLYURETHANE elastomers, COPOLYMERIZATION, GLASS transition temperature, BULK solids, HOLE mobility
Abstract

Polar polythiophenes with oligoethylene glycol side chains are exceedingly soft materials. A low glass transition temperature and low degree of crystallinity prevents their use as a bulk material. The synthesis of a copolymer comprising 1) soft polythiophene blocks with tetraethylene glycol side chains, and 2) hard urethane segments is reported. The molecular design is contrary to that of other semiconductor‐insulator copolymers, which typically combine a soft nonconjugated spacer with hard conjugated segments. Copolymerization of polar polythiophenes and urethane segments results in a ductile material that can be used as a free‐standing solid. The copolymer displays a storage modulus of 25 MPa at room temperature, elongation at break of 95%, and a reduced degree of swelling due to hydrogen bonding. Both chemical doping and electrochemical oxidation reveal that the introduction of urethane segments does not unduly reduce the hole charge‐carrier mobility and ability to take up charge. Further, stable operation is observed when the copolymer is used as the active layer of organic electrochemical transistors. [ABSTRACT FROM AUTHOR]

Published
2021
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16. Climate‐Dependent Heat‐Triggered Opening Mechanism of Banksia Seed Pods

Author

Huss, Jessica C., primary, Schoeppler, Vanessa, additional, Merritt, David J., additional, Best, Christine, additional, Maire, Eric, additional, Adrien, Jérôme, additional, Spaeker, Oliver, additional, Janssen, Nils, additional, Gladisch, Johannes, additional, Gierlinger, Notburga, additional, Miller, Ben P., additional, Fratzl, Peter, additional, and Eder, Michaela, additional

Published
2017
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19. Climate‐Dependent Heat‐Triggered Opening Mechanism of <italic>Banksia</italic> Seed Pods.

Author

Huss, Jessica C., Schoeppler, Vanessa, Merritt, David J., Best, Christine, Maire, Eric, Adrien, Jérôme, Spaeker, Oliver, Janssen, Nils, Gladisch, Johannes, Gierlinger, Notburga, Miller, Ben P., Fratzl, Peter, and Eder, Michaela

Abstract

Abstract: Heat‐triggered fruit opening and delayed release of mature seeds are widespread among plants in fire‐prone ecosystems. Here, the material characteristics of the seed‐containing follicles of Banksia attenuata (Proteaceae), which open in response to heat frequently caused by fire, are investigated. Material analysis reveals that long‐term dimensional stability and opening temperatures of follicles collected across an environmental gradient increase as habitats become drier, hotter, and more fire prone. A gradual increase in the biaxial curvature of the hygroscopic valves provides the follicles in the driest region with the highest flexural rigidity. The irreversible deformation of the valves for opening is enabled via a temperature‐dependent reduction of the elastic modulus of the innermost tissue layer, which then allows releasing the stresses previously generated by shrinkage of the fiber bundles in the adjacent layer during follicle drying. These findings illustrate the level of sophistication by which this species optimizes its fruit opening mechanism over a large distribution range with varying environmental conditions, and may not only have great relevance for developing biomimetic actuators, but also for elucidating the species' capacity to cope with climatic changes. [ABSTRACT FROM AUTHOR]

Published
2018
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20. Reversible Electronic Solid–Gel Switching of a Conjugated Polymer.

Author

Gladisch, Johannes, Stavrinidou, Eleni, Ghosh, Sarbani, Giovannitti, Alexander, Moser, Maximilian, Zozoulenko, Igor, McCulloch, Iain, and Berggren, Magnus

Subjects
*CONJUGATED polymers, *ION exchange (Chemistry), *CARBON electrodes, *ELECTROACTIVE substances, *PERCOLATION, *POLYMERS
Abstract

Conjugated polymers exhibit electrically driven volume changes when included in electrochemical devices via the exchange of ions and solvent. So far, this volumetric change is limited to 40% and 100% for reversible and irreversible systems, respectively, thus restricting potential applications of this technology. A conjugated polymer that reversibly expands by about 300% upon addressing, relative to its previous contracted state, while the first irreversible actuation can achieve values ranging from 1000–10 000%, depending on the voltage applied is reported. From experimental and theoretical studies, it is found that this large and reversible volumetric switching is due to reorganization of the polymer during swelling as it transforms between a solid‐state phase and a gel, while maintaining percolation for conductivity. The polymer is utilized as an electroactive cladding to reduce the void sizes of a porous carbon filter electrode by 85%. [ABSTRACT FROM AUTHOR]

Published
2020
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