{"id":{"repo_id":"tu-berlin","oai_identifier":"oai:depositonce.tu-berlin.de:11303/25542"},"canonical_url":"https://search.dev.ndltd.org/etd/tu-berlin/oai:depositonce.tu-berlin.de:11303/25542","repository":{"repo_id":"tu-berlin","name":"Technische Universität Berlin","base_url":"https://api-depositonce.tu-berlin.de/server/oai/request"},"display":{"title":"Application-oriented development of thermoplastic polyurethanes with shape memory properties","abstract":"Shape memory polymers (SMPs) are smart materials, that are capable of changing their shape in response to an external stimulus, typically a change in (ambient) temperature. This change in shape is commonly triggered after a thermomechanical treatment, enabling them to return to their original shape, so-called “one-way shape memory effect” (1W-SME). The switching between two shapes as a function of temperature, is known as the “two-way shape memory effect” (2W-SME). This thermoresponsiveness makes them highly interesting for the use as system components in e.g. programmable materials. Programmable materials act self-sufficiently, combining sensory and actuation properties in a single material. Thus, SMPs are providing the entire system a responsiveness to react actively to temperature changes. This makes them suitable for a wide range of applications with a high degree of functionality. Thermoplastic polyurethanes (TPUs) can exhibit such shape memory properties. This is due to their copolymer structure and phase-segregated morphology, which impart shape memory characteristics to the TPUs. TPUs consist of a soft segment (SS) and a hard segment (HS). The SS is composed of an oligomeric diol, while the HS consists of a diisocyanate and a short diol. Various combinations of these three building blocks allow for a wide range of molecular compounds to be synthesized. Every resulting TPU exhibits a unique property profile that can be used to address different applications. This thesis deals with the application-oriented synthesis of TPUs with shape memory properties. Motivated by the numerous variation possibilities, TPUs with diverse property profiles can be produced and customized through the appropriate selection of monomers, stoichiometry and synthesis parameters. This opens up opportunities to extend the functionality of existing applications or unlock entirely new ones. The aim was to synthesize TPUs efficiently and to investigate their structure-property and structure-functionality relationships. Therewith, the tailoring of TPUs according to requirements given by various applications became possible. By evaluating suitable synthesis conditions, different TPUs were synthesized. The synthesis procedure was scalable and transferable to various TPUs. The HS, consisting of 1,4-butanediol and 4,4’-methylene diphenyl diisocyanate, was kept constant in the study, while the SS and the HS/SS ratio were systematically varied to gain insights into the structure-property relationships. At the same time, the precondition was to adjust the phase transition of the SS, which is crucial for the 1W- and 2W-SME, above 23 °C to trigger a shape change \"on demand\". The focus was placed on polyester- and polyether-based TPUs and to compare their structure-property relationships. For polyester-based TPUs, higher molecular weights of the SS and a lower HS/SS ratio led to elastic, semi-crystalline materials with a phase transition of the SS above 23 °C. Due to high crystallinity, these TPUs were capable of a 2W-SME once thermomechanically treated. It was shown how the 2W-SME could be influenced by factors such as monomer selection, changes in deformation temperature and strain during thermomechanical treatment, electron radiation or actuation under constant load conditions. For polyether-based TPUs, low molecular weights of the SS and high HS contents resulted in amorphous TPUs with a glass transition above room temperature. Unlike the polyester-based TPUs, these materials were stiffer and capable of showing a 1W-SME directly after additive manufacturing (4D-printing) without the need of an additional programming step. The structure-property relationships and material characteristics allowed for targeted customization of TPUs. The 2W-SME of polyester-based TPUs enabled actuation in soft robotics, for instance. A polydecylene adipate-based TPU exhibiting a SS molecular weight of 3300 g × mol−1 and a HS content of 15 wt.% was developed and processed into actuators. Incorporating these into a gripper system enabled lifting and lowering a hen’s egg when the temperature was cycled between 23 °C and 64 °C. Additionally, the actuators were combined with mechanical unit cells to reversibly change their mechanical state as a function of temperature or to open and close small apertures in the unit cell structure. Actuators made from synthesized polydecylene sebacate-TPU with a SS molecular weight of 2800 g × mol−1 and a HS content of 20 wt.% were developed for use in latent heat storage systems for a programmable heat release. A demonstrator showed how the material synergistically interacted with a switchable phase change material (sPCM). The 2W-SME of the TPU was able to induce repeatedly crystallization of the sPCM. For polyether-based TPUs, a synthesized polypropylene glycol-based TPU with a SS molecular weight of 430 g × mol−1 and a HS content of 60 wt.% had a pronounced 1W-SME after 4D-printing, high mechanical stiffness and high adaptability due to its sharp decrease in storage modulus when exceeding the glass transition temperature. This enabled adaptive stiffness functionality, demonstrated by an at room temperature mechanically stable hands-free door opener that could be adaptively applied to a door handle through the activation of the 1W-SME after 4D-printing. Upon heating afterwards, the material became soft for detaching the item. Furthermore, it was non-cytotoxic, transparent and water-responsive. This allowed for the use in medical applications such as orthodontics. Aligners were fabricated from the material, demonstrating both water- and thermo-responsive 1W-SME on dental models. These aligners imply the adjustments of precise force as well as reduction of correction steps for superior functional therapeutic methods in the future. Further potential applications were discussed and referenced, including functional car-wrapping foils, smart textiles, intelligent microfluidics and components for smart assembly and disassembly, among others. This illustrates the versatility and adaptability of TPUs in their application spectrum. The prerequisite and basis for this is an application-oriented synthesis and tailoring of material characteristics based on their structure-property relationships, which were investigated and evaluated in this thesis.","abstract_html":"Shape memory polymers (SMPs) are smart materials, that are capable of changing their shape in response to an external stimulus, typically a change in (ambient) temperature. This change in shape is commonly triggered after a thermomechanical treatment, enabling them to return to their original shape, so-called “one-way shape memory effect” (1W-SME). The switching between two shapes as a function of temperature, is known as the “two-way shape memory effect” (2W-SME). This thermoresponsiveness makes them highly interesting for the use as system components in e.g. programmable materials. Programmable materials act self-sufficiently, combining sensory and actuation properties in a single material. Thus, SMPs are providing the entire system a responsiveness to react actively to temperature changes. This makes them suitable for a wide range of applications with a high degree of functionality. Thermoplastic polyurethanes (TPUs) can exhibit such shape memory properties. This is due to their copolymer structure and phase-segregated morphology, which impart shape memory characteristics to the TPUs. TPUs consist of a soft segment (SS) and a hard segment (HS). The SS is composed of an oligomeric diol, while the HS consists of a diisocyanate and a short diol. Various combinations of these three building blocks allow for a wide range of molecular compounds to be synthesized. Every resulting TPU exhibits a unique property profile that can be used to address different applications. This thesis deals with the application-oriented synthesis of TPUs with shape memory properties. Motivated by the numerous variation possibilities, TPUs with diverse property profiles can be produced and customized through the appropriate selection of monomers, stoichiometry and synthesis parameters. This opens up opportunities to extend the functionality of existing applications or unlock entirely new ones. The aim was to synthesize TPUs efficiently and to investigate their structure-property and structure-functionality relationships. Therewith, the tailoring of TPUs according to requirements given by various applications became possible. By evaluating suitable synthesis conditions, different TPUs were synthesized. The synthesis procedure was scalable and transferable to various TPUs. The HS, consisting of 1,4-butanediol and 4,4’-methylene diphenyl diisocyanate, was kept constant in the study, while the SS and the HS/SS ratio were systematically varied to gain insights into the structure-property relationships. At the same time, the precondition was to adjust the phase transition of the SS, which is crucial for the 1W- and 2W-SME, above 23 °C to trigger a shape change "on demand". The focus was placed on polyester- and polyether-based TPUs and to compare their structure-property relationships. For polyester-based TPUs, higher molecular weights of the SS and a lower HS/SS ratio led to elastic, semi-crystalline materials with a phase transition of the SS above 23 °C. Due to high crystallinity, these TPUs were capable of a 2W-SME once thermomechanically treated. It was shown how the 2W-SME could be influenced by factors such as monomer selection, changes in deformation temperature and strain during thermomechanical treatment, electron radiation or actuation under constant load conditions. For polyether-based TPUs, low molecular weights of the SS and high HS contents resulted in amorphous TPUs with a glass transition above room temperature. Unlike the polyester-based TPUs, these materials were stiffer and capable of showing a 1W-SME directly after additive manufacturing (4D-printing) without the need of an additional programming step. The structure-property relationships and material characteristics allowed for targeted customization of TPUs. The 2W-SME of polyester-based TPUs enabled actuation in soft robotics, for instance. A polydecylene adipate-based TPU exhibiting a SS molecular weight of 3300 g × mol−1 and a HS content of 15 wt.% was developed and processed into actuators. Incorporating these into a gripper system enabled lifting and lowering a hen’s egg when the temperature was cycled between 23 °C and 64 °C. Additionally, the actuators were combined with mechanical unit cells to reversibly change their mechanical state as a function of temperature or to open and close small apertures in the unit cell structure. Actuators made from synthesized polydecylene sebacate-TPU with a SS molecular weight of 2800 g × mol−1 and a HS content of 20 wt.% were developed for use in latent heat storage systems for a programmable heat release. A demonstrator showed how the material synergistically interacted with a switchable phase change material (sPCM). The 2W-SME of the TPU was able to induce repeatedly crystallization of the sPCM. For polyether-based TPUs, a synthesized polypropylene glycol-based TPU with a SS molecular weight of 430 g × mol−1 and a HS content of 60 wt.% had a pronounced 1W-SME after 4D-printing, high mechanical stiffness and high adaptability due to its sharp decrease in storage modulus when exceeding the glass transition temperature. This enabled adaptive stiffness functionality, demonstrated by an at room temperature mechanically stable hands-free door opener that could be adaptively applied to a door handle through the activation of the 1W-SME after 4D-printing. Upon heating afterwards, the material became soft for detaching the item. Furthermore, it was non-cytotoxic, transparent and water-responsive. This allowed for the use in medical applications such as orthodontics. Aligners were fabricated from the material, demonstrating both water- and thermo-responsive 1W-SME on dental models. These aligners imply the adjustments of precise force as well as reduction of correction steps for superior functional therapeutic methods in the future. Further potential applications were discussed and referenced, including functional car-wrapping foils, smart textiles, intelligent microfluidics and components for smart assembly and disassembly, among others. This illustrates the versatility and adaptability of TPUs in their application spectrum. The prerequisite and basis for this is an application-oriented synthesis and tailoring of material characteristics based on their structure-property relationships, which were investigated and evaluated in this thesis.","abstract_has_math":false,"creators":["Schönfeld, Dennis"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Pretsch, Thorsten"],"committee_chairs":[],"committee_members":[],"year":2025,"date_issued":"2025","date_published":"2025","updated_at":"2026-07-27T21:28:42Z","subjects":[],"languages":["en"],"rights":[],"rights_urls":["https://creativecommons.org/licenses/by-nc-nd/4.0/"],"identifier_entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://doi.org/10.14279/depositonce-24365"],"render_values":[{"text":"https://doi.org/10.14279/depositonce-24365","href":"https://doi.org/10.14279/depositonce-24365","code":true}]}]},"links":{"outbound_url":"https://depositonce.tu-berlin.de/handle/11303/25542","outbound_label":"Repository record","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Pretsch, Thorsten"]},{"key":"dc:creator","label":"Author","values":["Schönfeld, Dennis"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2025-11-20T14:18:36Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2025-11-20T14:18:36Z"]},{"key":"dc:date.issued","label":"Date","values":["2025"]},{"key":"dc:type","label":"Dc Type","values":["Doctoral Thesis"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]},{"key":"dc:rights.uri","label":"Rights URI","values":["https://creativecommons.org/licenses/by-nc-nd/4.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://depositonce.tu-berlin.de/handle/11303/25542","https://doi.org/10.14279/depositonce-24365"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Shape memory polymers (SMPs) are smart materials, that are capable of changing their shape in response to an external stimulus, typically a change in (ambient) temperature. This change in shape is commonly triggered after a thermomechanical treatment, enabling them to return to their original shape, so-called “one-way shape memory effect” (1W-SME). The switching between two shapes as a function of temperature, is known as the “two-way shape memory effect” (2W-SME). This thermoresponsiveness makes them highly interesting for the use as system components in e.g. programmable materials. Programmable materials act self-sufficiently, combining sensory and actuation properties in a single material. Thus, SMPs are providing the entire system a responsiveness to react actively to temperature changes. This makes them suitable for a wide range of applications with a high degree of functionality. Thermoplastic polyurethanes (TPUs) can exhibit such shape memory properties. This is due to their copolymer structure and phase-segregated morphology, which impart shape memory characteristics to the TPUs. TPUs consist of a soft segment (SS) and a hard segment (HS). The SS is composed of an oligomeric diol, while the HS consists of a diisocyanate and a short diol. Various combinations of these three building blocks allow for a wide range of molecular compounds to be synthesized. Every resulting TPU exhibits a unique property profile that can be used to address different applications. This thesis deals with the application-oriented synthesis of TPUs with shape memory properties. Motivated by the numerous variation possibilities, TPUs with diverse property profiles can be produced and customized through the appropriate selection of monomers, stoichiometry and synthesis parameters. This opens up opportunities to extend the functionality of existing applications or unlock entirely new ones. The aim was to synthesize TPUs efficiently and to investigate their structure-property and structure-functionality relationships. Therewith, the tailoring of TPUs according to requirements given by various applications became possible. By evaluating suitable synthesis conditions, different TPUs were synthesized. The synthesis procedure was scalable and transferable to various TPUs. The HS, consisting of 1,4-butanediol and 4,4’-methylene diphenyl diisocyanate, was kept constant in the study, while the SS and the HS/SS ratio were systematically varied to gain insights into the structure-property relationships. At the same time, the precondition was to adjust the phase transition of the SS, which is crucial for the 1W- and 2W-SME, above 23 °C to trigger a shape change \"on demand\". The focus was placed on polyester- and polyether-based TPUs and to compare their structure-property relationships. For polyester-based TPUs, higher molecular weights of the SS and a lower HS/SS ratio led to elastic, semi-crystalline materials with a phase transition of the SS above 23 °C. Due to high crystallinity, these TPUs were capable of a 2W-SME once thermomechanically treated. It was shown how the 2W-SME could be influenced by factors such as monomer selection, changes in deformation temperature and strain during thermomechanical treatment, electron radiation or actuation under constant load conditions. For polyether-based TPUs, low molecular weights of the SS and high HS contents resulted in amorphous TPUs with a glass transition above room temperature. Unlike the polyester-based TPUs, these materials were stiffer and capable of showing a 1W-SME directly after additive manufacturing (4D-printing) without the need of an additional programming step. The structure-property relationships and material characteristics allowed for targeted customization of TPUs. The 2W-SME of polyester-based TPUs enabled actuation in soft robotics, for instance. A polydecylene adipate-based TPU exhibiting a SS molecular weight of 3300 g × mol−1 and a HS content of 15 wt.% was developed and processed into actuators. Incorporating these into a gripper system enabled lifting and lowering a hen’s egg when the temperature was cycled between 23 °C and 64 °C. Additionally, the actuators were combined with mechanical unit cells to reversibly change their mechanical state as a function of temperature or to open and close small apertures in the unit cell structure. Actuators made from synthesized polydecylene sebacate-TPU with a SS molecular weight of 2800 g × mol−1 and a HS content of 20 wt.% were developed for use in latent heat storage systems for a programmable heat release. A demonstrator showed how the material synergistically interacted with a switchable phase change material (sPCM). The 2W-SME of the TPU was able to induce repeatedly crystallization of the sPCM. For polyether-based TPUs, a synthesized polypropylene glycol-based TPU with a SS molecular weight of 430 g × mol−1 and a HS content of 60 wt.% had a pronounced 1W-SME after 4D-printing, high mechanical stiffness and high adaptability due to its sharp decrease in storage modulus when exceeding the glass transition temperature. This enabled adaptive stiffness functionality, demonstrated by an at room temperature mechanically stable hands-free door opener that could be adaptively applied to a door handle through the activation of the 1W-SME after 4D-printing. Upon heating afterwards, the material became soft for detaching the item. Furthermore, it was non-cytotoxic, transparent and water-responsive. This allowed for the use in medical applications such as orthodontics. Aligners were fabricated from the material, demonstrating both water- and thermo-responsive 1W-SME on dental models. These aligners imply the adjustments of precise force as well as reduction of correction steps for superior functional therapeutic methods in the future. Further potential applications were discussed and referenced, including functional car-wrapping foils, smart textiles, intelligent microfluidics and components for smart assembly and disassembly, among others. This illustrates the versatility and adaptability of TPUs in their application spectrum. The prerequisite and basis for this is an application-oriented synthesis and tailoring of material characteristics based on their structure-property relationships, which were investigated and evaluated in this thesis.","Formgedächtnispolymere (FGPs) sind intelligente Materialien, die ihre Form als Reaktion auf einen externen Stimulus, typischerweise eine Änderung der (Umgebungs-)Temperatur, ändern können. Nach thermomechanischer Behandlung sind sie in der Lage zu ihrer ursprünglichen Form zurückzukehren, sog. Einwegeformgedächtniseffekt (1W-FGE). Der Wechsel zwischen zwei Formen als Funktion der Temperatur ist der sog. Zweiwege-formgedächtniseffekt (2W-FGE). Diese Thermoresponsivität macht sie hochinteressant im Einsatz als Systemkomponente in z.B. programmierbaren Materialien. Programmierbare Materialien agieren autark und vereinen sensorisch und aktuatorische Eigenschaften in einem Material. Somit verleihen FGPs dem Gesamtsystem die Eigenschaft, aktiv auf Temperaturwechsel zu reagieren. Dies prädestiniert sie für den Einsatz unterschiedlichster Anwendungen mit hohem Grad an Funktionalität. Thermoplastische Polyurethane (TPUs) können solche Formgedächtniseigenschaften aufweisen. Dies liegt an ihrer copolymeren Struktur und eine phasensegregierte Morphologie, die den TPUs Formgedächtniseigenschaften verleiht. TPUs bestehen aus einem Weichsegment (WS) und Hartsegment (HS). Das WS besteht aus einem oligomeren Diol, während das HS aus einem Diisocyanat und einem kurzkettigen Diol besteht. Verschiedene Kombinationen dieser drei Bausteine ermöglichen die Synthese einer Vielzahl molekularer Verbindungen. Jedes resultierende TPU weist ein einzigartiges Eigenschaftsprofil auf, das für verschiedene Anwendungen genutzt werden kann. Die Arbeit befasst sich mit der applikations-orientierten Synthese von TPUs mit Formgedächtniseigenschaften. Motiviert durch die zahlreichen Variationsmöglichkeiten können TPUs mit unterschiedlichstem Eigenschaftsprofilen durch geeignete Auswahl an Monomer, Stöchiometrie und Syntheseparameter hergestellt und angepasst werden. Dies eröffnet Möglichkeiten, die Funktionalität bestehender Anwendungen zu erweitern oder völlig neue Applikationen zu erschließen. Ziel war es, TPUs effizient zu synthetisieren und ihre Struktur-Eigenschafts- und Struktur-Funktionalitäts-Beziehungen zu untersuchen. Damit war es möglich, TPUs entsprechend den Randbedingungen und Anforderungen verschiedener Anwendungen anzupassen und maßzuschneidern. Durch die Evaluation geeigneter Synthesebedingungen wurden verschiedene TPUs synthetisiert. Die Syntheseprozedur war skalierbar und auf verschiedene TPUs übertragbar. Das HS, bestehend aus 1,4-Butandiol und 4,4‘-Diphenylmethandiisocyanat, wurde in der Arbeit identisch gehalten und, während das WS und die HS/WS-Anteile systematisch variiert wurden, um Einblicke in die Struktur-Eigenschafts-Beziehungen zu erhalten. Gleichzeitig war die Voraussetzung, den Phasenübergangs des WS, der ausschlaggebend für den 1W- und 2W-FGE ist, oberhalb von 23 °C einzustellen, um eine Formänderung „auf Knopfdruck“ abrufen zu können. Der Fokus lag auf polyester- und polyether-basierten TPUs und dem Vergleich ihrer Struktur-Eigenschafts-Beziehungen. Für polyester-basierte TPUs führten höhere Molekulargewichte des WS und ein geringes HS/WS-Verhältnis zu elastischen, semi-kristallinen Materialien mit einem Phasenübergang des WS oberhalb 23 °C. Aufgrund der hohen Kristallinität waren diese TPUs nach thermomechanischer Behandlung in der Lage, einen 2W-FGE auszuführen. Es wurde gezeigt, wie der 2W-FGE durch Faktoren wie Monomehrauswahl, Änderungen der Deformationstemperatur und -dehnung während der thermomechanischen Behandlung, Elektronenbestrahlung oder Aktuation unter konstanter Last beeinflusst werden kann. Für polyether-basierte TPUs führten niedrige Molekulargewichte des WS und hohe HS-Gehalte zu amorphen TPU mit einem Glasübergang oberhalb der Raumtemperatur. Im Gegensatz zu den polyester-basierten TPUs waren diese Materialien steifer und in der Lage einen 1W-FGE direkt nach additiver Fertigung (4D-Druck) zu zeigen ohne zusätzlich benötigter thermomechanischer Behandlung. Die Struktur-Eigenschafts-Beziehungen und Materialcharakteristika erlaubten ein gezieltes Maßschneidern von TPUs. Der 2W-FGE polyester-basierter TPUs ermöglichte beispielsweise eine Aktorik für die weiche Robotik. Ein Polydecylenadipat-basiertes TPU mit einem WS-Molekulargewicht von 3300 g × mol−1 und einem HS-Gehalt von 15 Gew.-% wurde entwickelt und zu Aktoren verarbeitet. Die Integration eines solchen Aktorelements in ein Greifersystem ermöglichte das Heben und Senken eines Hühnereis, wenn die Temperatur zwischen 23 °C und 64 °C gezykelt wurde. Zusätzlich wurden Aktoren mit mechanischen Einheitszellen kombiniert, um ihren mechanischen Zustand reversibel als Funktion der Temperatur zu ändern oder kleine Öffnungen in der Einheitszellenstruktur zu öffnen und zu schließen. Aktuatoren aus einem synthetisierten Polydecyclensebacat-TPU mit einem WS-Molekulargewicht von 2800 g × mol−1 und einem HS-Gehalt von 20 Gew.-% wurden für den Einsatz in latente Wärmespeichersysteme zur programmierbaren Wärmeabgabe entwickelt. Ein Demonstrator zeigte, wie das Material synergistisch mit einem schaltbaren Phasenwechselmaterial (sPCM) interagierte. Der 2W-FGE des TPU konnte wiederholt eine Kristallisation des sPCM induzieren. Für Polyether-basierte TPUs zeigte ein synthetisiertes Polypropylenglycol-basiertes TPU mit einem WS-Molekulargewicht von 430 g × mol−1 und einem HS-Gehalt von 60 Gew.-% einen ausgeprägten 1W-FGE nach dem 4D-Druck, hohe mechanische Steifigkeit und hohe Adaptivität aufgrund seiner scharfen Abnahme des Speichermoduls beim Überschreiten der Glasübergangstemperatur. Dies ermöglichte eine adaptive Steifigkeitsfunktionalität, demonstriert durch einen bei Raumtemperatur mechanisch stabilen freihändigen Türöffner, der adaptiv auf einen Türgriff durch Auslösen des 1W-FGE nach dem 4D-Druck aufgebracht werden konnte. Durch anschließendes Erwärmen wurde das Material weich, um den Türöffner wieder abnehmen zu können. Darüber hinaus war es nicht zytotoxisch, transparent und wasserresponsiv. Dies ermöglichte den Einsatz in medizinischen Anwendungen wie der Kieferorthopädie. Aligner wurden aus dem Material gefertigt, die sowohl einen wasser- als auch thermoresponsiven 1W-FGE an Zahnmodellen zeigten. Solche Aligner ermöglichen eine präzise Einstellung der Kraft, sowie die Reduzierung von Korrekturschritten für zukünftig funktionellere Therapiemethoden. Weitere potenzielle Anwendungen wurden vorgestellt und diskutiert, darunter funktionelle Fahrzeugfolierungen, smarte Textilien, intelligente Mikrofluidik, Komponenten für die smarte Montage und Demontage, uvm. Dies verdeutlicht die Vielseitigkeit und Adaptivität von TPUs in ihrem Anwendungsspektrum. Voraussetzung und Grundlage hierfür ist eine applikations-orientierte Synthese und das Maßschneidern des Materialeigenschaftsprofils auf Basis der Struktur-Eigenschafts-Beziehungen, welches in der Arbeit untersucht und evaluiert wurde."]},{"key":"dc:title","label":"Title","values":["Application-oriented development of thermoplastic polyurethanes with shape memory properties"]}]}],"canonical_facts":{"dc:contributor.advisor":["Pretsch, Thorsten"],"dc:creator":["Schönfeld, Dennis"],"dc:date.accessioned":["2025-11-20T14:18:36Z"],"dc:date.available":["2025-11-20T14:18:36Z"],"dc:date.issued":["2025"],"dc:description.abstract":["Shape memory polymers (SMPs) are smart materials, that are capable of changing their shape in response to an external stimulus, typically a change in (ambient) temperature. This change in shape is commonly triggered after a thermomechanical treatment, enabling them to return to their original shape, so-called “one-way shape memory effect” (1W-SME). The switching between two shapes as a function of temperature, is known as the “two-way shape memory effect” (2W-SME). This thermoresponsiveness makes them highly interesting for the use as system components in e.g. programmable materials. Programmable materials act self-sufficiently, combining sensory and actuation properties in a single material. Thus, SMPs are providing the entire system a responsiveness to react actively to temperature changes. This makes them suitable for a wide range of applications with a high degree of functionality. Thermoplastic polyurethanes (TPUs) can exhibit such shape memory properties. This is due to their copolymer structure and phase-segregated morphology, which impart shape memory characteristics to the TPUs. TPUs consist of a soft segment (SS) and a hard segment (HS). The SS is composed of an oligomeric diol, while the HS consists of a diisocyanate and a short diol. Various combinations of these three building blocks allow for a wide range of molecular compounds to be synthesized. Every resulting TPU exhibits a unique property profile that can be used to address different applications. This thesis deals with the application-oriented synthesis of TPUs with shape memory properties. Motivated by the numerous variation possibilities, TPUs with diverse property profiles can be produced and customized through the appropriate selection of monomers, stoichiometry and synthesis parameters. This opens up opportunities to extend the functionality of existing applications or unlock entirely new ones. The aim was to synthesize TPUs efficiently and to investigate their structure-property and structure-functionality relationships. Therewith, the tailoring of TPUs according to requirements given by various applications became possible. By evaluating suitable synthesis conditions, different TPUs were synthesized. The synthesis procedure was scalable and transferable to various TPUs. The HS, consisting of 1,4-butanediol and 4,4’-methylene diphenyl diisocyanate, was kept constant in the study, while the SS and the HS/SS ratio were systematically varied to gain insights into the structure-property relationships. At the same time, the precondition was to adjust the phase transition of the SS, which is crucial for the 1W- and 2W-SME, above 23 °C to trigger a shape change \"on demand\". The focus was placed on polyester- and polyether-based TPUs and to compare their structure-property relationships. For polyester-based TPUs, higher molecular weights of the SS and a lower HS/SS ratio led to elastic, semi-crystalline materials with a phase transition of the SS above 23 °C. Due to high crystallinity, these TPUs were capable of a 2W-SME once thermomechanically treated. It was shown how the 2W-SME could be influenced by factors such as monomer selection, changes in deformation temperature and strain during thermomechanical treatment, electron radiation or actuation under constant load conditions. For polyether-based TPUs, low molecular weights of the SS and high HS contents resulted in amorphous TPUs with a glass transition above room temperature. Unlike the polyester-based TPUs, these materials were stiffer and capable of showing a 1W-SME directly after additive manufacturing (4D-printing) without the need of an additional programming step. The structure-property relationships and material characteristics allowed for targeted customization of TPUs. The 2W-SME of polyester-based TPUs enabled actuation in soft robotics, for instance. A polydecylene adipate-based TPU exhibiting a SS molecular weight of 3300 g × mol−1 and a HS content of 15 wt.% was developed and processed into actuators. Incorporating these into a gripper system enabled lifting and lowering a hen’s egg when the temperature was cycled between 23 °C and 64 °C. Additionally, the actuators were combined with mechanical unit cells to reversibly change their mechanical state as a function of temperature or to open and close small apertures in the unit cell structure. Actuators made from synthesized polydecylene sebacate-TPU with a SS molecular weight of 2800 g × mol−1 and a HS content of 20 wt.% were developed for use in latent heat storage systems for a programmable heat release. A demonstrator showed how the material synergistically interacted with a switchable phase change material (sPCM). The 2W-SME of the TPU was able to induce repeatedly crystallization of the sPCM. For polyether-based TPUs, a synthesized polypropylene glycol-based TPU with a SS molecular weight of 430 g × mol−1 and a HS content of 60 wt.% had a pronounced 1W-SME after 4D-printing, high mechanical stiffness and high adaptability due to its sharp decrease in storage modulus when exceeding the glass transition temperature. This enabled adaptive stiffness functionality, demonstrated by an at room temperature mechanically stable hands-free door opener that could be adaptively applied to a door handle through the activation of the 1W-SME after 4D-printing. Upon heating afterwards, the material became soft for detaching the item. Furthermore, it was non-cytotoxic, transparent and water-responsive. This allowed for the use in medical applications such as orthodontics. Aligners were fabricated from the material, demonstrating both water- and thermo-responsive 1W-SME on dental models. These aligners imply the adjustments of precise force as well as reduction of correction steps for superior functional therapeutic methods in the future. Further potential applications were discussed and referenced, including functional car-wrapping foils, smart textiles, intelligent microfluidics and components for smart assembly and disassembly, among others. This illustrates the versatility and adaptability of TPUs in their application spectrum. The prerequisite and basis for this is an application-oriented synthesis and tailoring of material characteristics based on their structure-property relationships, which were investigated and evaluated in this thesis.","Formgedächtnispolymere (FGPs) sind intelligente Materialien, die ihre Form als Reaktion auf einen externen Stimulus, typischerweise eine Änderung der (Umgebungs-)Temperatur, ändern können. Nach thermomechanischer Behandlung sind sie in der Lage zu ihrer ursprünglichen Form zurückzukehren, sog. Einwegeformgedächtniseffekt (1W-FGE). Der Wechsel zwischen zwei Formen als Funktion der Temperatur ist der sog. Zweiwege-formgedächtniseffekt (2W-FGE). Diese Thermoresponsivität macht sie hochinteressant im Einsatz als Systemkomponente in z.B. programmierbaren Materialien. Programmierbare Materialien agieren autark und vereinen sensorisch und aktuatorische Eigenschaften in einem Material. Somit verleihen FGPs dem Gesamtsystem die Eigenschaft, aktiv auf Temperaturwechsel zu reagieren. Dies prädestiniert sie für den Einsatz unterschiedlichster Anwendungen mit hohem Grad an Funktionalität. Thermoplastische Polyurethane (TPUs) können solche Formgedächtniseigenschaften aufweisen. Dies liegt an ihrer copolymeren Struktur und eine phasensegregierte Morphologie, die den TPUs Formgedächtniseigenschaften verleiht. TPUs bestehen aus einem Weichsegment (WS) und Hartsegment (HS). Das WS besteht aus einem oligomeren Diol, während das HS aus einem Diisocyanat und einem kurzkettigen Diol besteht. Verschiedene Kombinationen dieser drei Bausteine ermöglichen die Synthese einer Vielzahl molekularer Verbindungen. Jedes resultierende TPU weist ein einzigartiges Eigenschaftsprofil auf, das für verschiedene Anwendungen genutzt werden kann. Die Arbeit befasst sich mit der applikations-orientierten Synthese von TPUs mit Formgedächtniseigenschaften. Motiviert durch die zahlreichen Variationsmöglichkeiten können TPUs mit unterschiedlichstem Eigenschaftsprofilen durch geeignete Auswahl an Monomer, Stöchiometrie und Syntheseparameter hergestellt und angepasst werden. Dies eröffnet Möglichkeiten, die Funktionalität bestehender Anwendungen zu erweitern oder völlig neue Applikationen zu erschließen. Ziel war es, TPUs effizient zu synthetisieren und ihre Struktur-Eigenschafts- und Struktur-Funktionalitäts-Beziehungen zu untersuchen. Damit war es möglich, TPUs entsprechend den Randbedingungen und Anforderungen verschiedener Anwendungen anzupassen und maßzuschneidern. Durch die Evaluation geeigneter Synthesebedingungen wurden verschiedene TPUs synthetisiert. Die Syntheseprozedur war skalierbar und auf verschiedene TPUs übertragbar. Das HS, bestehend aus 1,4-Butandiol und 4,4‘-Diphenylmethandiisocyanat, wurde in der Arbeit identisch gehalten und, während das WS und die HS/WS-Anteile systematisch variiert wurden, um Einblicke in die Struktur-Eigenschafts-Beziehungen zu erhalten. Gleichzeitig war die Voraussetzung, den Phasenübergangs des WS, der ausschlaggebend für den 1W- und 2W-FGE ist, oberhalb von 23 °C einzustellen, um eine Formänderung „auf Knopfdruck“ abrufen zu können. Der Fokus lag auf polyester- und polyether-basierten TPUs und dem Vergleich ihrer Struktur-Eigenschafts-Beziehungen. Für polyester-basierte TPUs führten höhere Molekulargewichte des WS und ein geringes HS/WS-Verhältnis zu elastischen, semi-kristallinen Materialien mit einem Phasenübergang des WS oberhalb 23 °C. Aufgrund der hohen Kristallinität waren diese TPUs nach thermomechanischer Behandlung in der Lage, einen 2W-FGE auszuführen. Es wurde gezeigt, wie der 2W-FGE durch Faktoren wie Monomehrauswahl, Änderungen der Deformationstemperatur und -dehnung während der thermomechanischen Behandlung, Elektronenbestrahlung oder Aktuation unter konstanter Last beeinflusst werden kann. Für polyether-basierte TPUs führten niedrige Molekulargewichte des WS und hohe HS-Gehalte zu amorphen TPU mit einem Glasübergang oberhalb der Raumtemperatur. Im Gegensatz zu den polyester-basierten TPUs waren diese Materialien steifer und in der Lage einen 1W-FGE direkt nach additiver Fertigung (4D-Druck) zu zeigen ohne zusätzlich benötigter thermomechanischer Behandlung. Die Struktur-Eigenschafts-Beziehungen und Materialcharakteristika erlaubten ein gezieltes Maßschneidern von TPUs. Der 2W-FGE polyester-basierter TPUs ermöglichte beispielsweise eine Aktorik für die weiche Robotik. Ein Polydecylenadipat-basiertes TPU mit einem WS-Molekulargewicht von 3300 g × mol−1 und einem HS-Gehalt von 15 Gew.-% wurde entwickelt und zu Aktoren verarbeitet. Die Integration eines solchen Aktorelements in ein Greifersystem ermöglichte das Heben und Senken eines Hühnereis, wenn die Temperatur zwischen 23 °C und 64 °C gezykelt wurde. Zusätzlich wurden Aktoren mit mechanischen Einheitszellen kombiniert, um ihren mechanischen Zustand reversibel als Funktion der Temperatur zu ändern oder kleine Öffnungen in der Einheitszellenstruktur zu öffnen und zu schließen. Aktuatoren aus einem synthetisierten Polydecyclensebacat-TPU mit einem WS-Molekulargewicht von 2800 g × mol−1 und einem HS-Gehalt von 20 Gew.-% wurden für den Einsatz in latente Wärmespeichersysteme zur programmierbaren Wärmeabgabe entwickelt. Ein Demonstrator zeigte, wie das Material synergistisch mit einem schaltbaren Phasenwechselmaterial (sPCM) interagierte. Der 2W-FGE des TPU konnte wiederholt eine Kristallisation des sPCM induzieren. Für Polyether-basierte TPUs zeigte ein synthetisiertes Polypropylenglycol-basiertes TPU mit einem WS-Molekulargewicht von 430 g × mol−1 und einem HS-Gehalt von 60 Gew.-% einen ausgeprägten 1W-FGE nach dem 4D-Druck, hohe mechanische Steifigkeit und hohe Adaptivität aufgrund seiner scharfen Abnahme des Speichermoduls beim Überschreiten der Glasübergangstemperatur. Dies ermöglichte eine adaptive Steifigkeitsfunktionalität, demonstriert durch einen bei Raumtemperatur mechanisch stabilen freihändigen Türöffner, der adaptiv auf einen Türgriff durch Auslösen des 1W-FGE nach dem 4D-Druck aufgebracht werden konnte. Durch anschließendes Erwärmen wurde das Material weich, um den Türöffner wieder abnehmen zu können. Darüber hinaus war es nicht zytotoxisch, transparent und wasserresponsiv. Dies ermöglichte den Einsatz in medizinischen Anwendungen wie der Kieferorthopädie. Aligner wurden aus dem Material gefertigt, die sowohl einen wasser- als auch thermoresponsiven 1W-FGE an Zahnmodellen zeigten. Solche Aligner ermöglichen eine präzise Einstellung der Kraft, sowie die Reduzierung von Korrekturschritten für zukünftig funktionellere Therapiemethoden. Weitere potenzielle Anwendungen wurden vorgestellt und diskutiert, darunter funktionelle Fahrzeugfolierungen, smarte Textilien, intelligente Mikrofluidik, Komponenten für die smarte Montage und Demontage, uvm. Dies verdeutlicht die Vielseitigkeit und Adaptivität von TPUs in ihrem Anwendungsspektrum. Voraussetzung und Grundlage hierfür ist eine applikations-orientierte Synthese und das Maßschneidern des Materialeigenschaftsprofils auf Basis der Struktur-Eigenschafts-Beziehungen, welches in der Arbeit untersucht und evaluiert wurde."],"dc:identifier.uri":["https://depositonce.tu-berlin.de/handle/11303/25542","https://doi.org/10.14279/depositonce-24365"],"dc:language.iso":["en"],"dc:rights.uri":["https://creativecommons.org/licenses/by-nc-nd/4.0/"],"dc:title":["Application-oriented development of thermoplastic polyurethanes with shape memory properties"],"dc:type":["Doctoral Thesis"]},"updated_at":"2026-07-27T21:28:42Z"}