Dokument-ID Dokumenttyp Verfasser/Autoren Herausgeber Haupttitel Abstract Auflage Verlagsort Verlag Erscheinungsjahr Seitenzahl Schriftenreihe Titel Schriftenreihe Bandzahl ISBN Quelle der Hochschulschrift Konferenzname Quelle:Titel Quelle:Jahrgang Quelle:Heftnummer Quelle:Erste Seite Quelle:Letzte Seite URN DOI Abteilungen OPUS4-8112 misc Nöchel, Ulrich; Reddy, Chaganti Srinivasa; Wang, Ke; Cui, Jing; Zizak, Ivo; Behl, Marc; Kratz, Karl; Lendlein, Andreas Nanostructural changes in crystallizable controlling units determine the temperature-memory of polymers Temperature-memory polymers remember the temperature, where they were deformed recently, enabled by broad thermal transitions. In this study, we explored a series of crosslinked poly[ethylene-co-(vinyl acetate)] networks (cPEVAs) comprising crystallizable polyethylene (PE) controlling units exhibiting a pronounced temperature-memory effect (TME) between 16 and 99 °C related to a broad melting transition (∼100 °C). The nanostructural changes in such cPEVAs during programming and activation of the TME were analyzed via in situ X-ray scattering and specific annealing experiments. Different contributions to the mechanism of memorizing high or low deformation temperatures (Tdeform) were observed in cPEVA, which can be associated to the average PE crystal sizes. At high deformation temperatures (>50 °C), newly formed PE crystals, which are established during cooling when fixing the temporary shape, dominated the TME mechanism. In contrast, at low Tdeform (<50 °C), corresponding to a cold drawing scenario, the deformation led preferably to a disruption of existing large crystals into smaller ones, which then fix the temporary shape upon cooling. The observed mechanism of memorizing a deformation temperature might enable the prediction of the TME behavior and the knowledge based design of other TMPs with crystallizable controlling units. 2015 9 8284 8293 urn:nbn:de:kobv:517-opus4-81124 Institut für Chemie OPUS4-8111 Wissenschaftlicher Artikel Nöchel, Ulrich; Reddy, Chaganti Srinivasa; Wang, Ke; Cui, Jing; Zizak, Ivo; Behl, Marc; Kratz, Karl; Lendlein, Andreas Nanostructural changes in crystallizable controlling units determine the temperature-memory of polymers Temperature-memory polymers remember the temperature, where they were deformed recently, enabled by broad thermal transitions. In this study, we explored a series of crosslinked poly[ethylene-co-(vinyl acetate)] networks (cPEVAs) comprising crystallizable polyethylene (PE) controlling units exhibiting a pronounced temperature-memory effect (TME) between 16 and 99 °C related to a broad melting transition (∼100 °C). The nanostructural changes in such cPEVAs during programming and activation of the TME were analyzed via in situ X-ray scattering and specific annealing experiments. Different contributions to the mechanism of memorizing high or low deformation temperatures (Tdeform) were observed in cPEVA, which can be associated to the average PE crystal sizes. At high deformation temperatures (>50 °C), newly formed PE crystals, which are established during cooling when fixing the temporary shape, dominated the TME mechanism. In contrast, at low Tdeform (<50 °C), corresponding to a cold drawing scenario, the deformation led preferably to a disruption of existing large crystals into smaller ones, which then fix the temporary shape upon cooling. The observed mechanism of memorizing a deformation temperature might enable the prediction of the TME behavior and the knowledge based design of other TMPs with crystallizable controlling units. Cambridge Royal Society of Chemistry 2015 9 Journal of Materials Chemistry A, Materials for energy and sustainability 16 3 8284 8293 10.1039/c4ta06586g Institut für Chemie OPUS4-39286 Wissenschaftlicher Artikel Wang, Weiwei; Kratz, Karl; Behl, Marc; Yan, Wan; Liu, Yue; Xu, Xun; Baudis, Stefan; Li, Zhengdong; Kurtz, Andreas; Lendlein, Andreas; Ma, Nan The interaction of adipose-derived human mesenchymal stem cells and polyether ether ketone Polyether ether ketone (PEEK) as a high-performance, thermoplastic implant material entered the field of medical applications due to its structural function and commercial availability. In bone tissue engineering, the combination of mesenchymal stem cells (MSCs) with PEEK implants may accelerate the bone formation and promote the osseointegration between the implant and the adjacent bone tissue. In this concept the question how PEEK influences the behaviour and functions of MSCs is of great interest. Here the cellular response of human adipose-derived MSCs to PEEK was evaluated and compared to tissue culture plate (TCP) as the reference material. Viability and morphology of cells were not altered when cultured on the PEEK film. The cells on PEEK presented a high proliferation activity in spite of a relatively lower initial cell adhesion rate. There was no significant difference on cell apoptosis and senescence between the cells on PEEK and TCP. The inflammatory cytokines and VEGF secreted by the cells on these two surfaces were at similar levels. The cells on PEEK showed up-regulated BMP2 and down-regulated BMP4 and BMP6 gene expression, whereas no conspicuous differences were observed in the committed osteoblast markers (BGLAP, COL1A1 and Runx2). With osteoinduction the cells on PEEK and TCP exhibited a similar osteogenic differentiation potential. Our results demonstrate the biofunctionality of PEEK for human MSC cultivation and differentiation. Its clinical benefits in bone tissue engineering may be achieved by combining MSCs with PEEK implants. These data may also provide useful information for further modification of PEEK with chemical or physical methods to regulate the cellular processes of MSCs and to consequently improve the efficacy of MSC-PEEK based therapies. Amsterdam IOS Press 2015 21 Clinical hemorheology and microcirculation : blood flow and vessels 61 2 301 321 10.3233/CH-152001 Institut für Chemie OPUS4-39362 Wissenschaftlicher Artikel Nöchel, Ulrich; Reddy, Chaganti Srinivasa; Wang, Ke; Cui, Jing; Zizak, Ivo; Behl, Marc; Kratz, Karl; Lendlein, Andreas Nanostructural changes in crystallizable controlling units determine the temperature-memory of polymers Temperature-memory polymers remember the temperature, where they were deformed recently, enabled by broad thermal transitions. In this study, we explored a series of crosslinked poly[ethylene-co-(vinyl acetate)] networks (cPEVAs) comprising crystallizable polyethylene (PE) controlling units exhibiting a pronounced temperature-memory effect (TME) between 16 and 99 degrees C related to a broad melting transition (similar to 100 degrees C). The nanostructural changes in such cPEVAs during programming and activation of the TME were analyzed via in situ X-ray scattering and specific annealing experiments. Different contributions to the mechanism of memorizing high or low deformation temperatures (T-deform) were observed in cPEVA, which can be associated to the average PE crystal sizes. At high deformation temperatures (>50 degrees C), newly formed PE crystals, which are established during cooling when fixing the temporary shape, dominated the TME mechanism. In contrast, at low T-deform (<50 degrees C), corresponding to a cold drawing scenario, the deformation led preferably to a disruption of existing large crystals into smaller ones, which then fix the temporary shape upon cooling. The observed mechanism of memorizing a deformation temperature might enable the prediction of the TME behavior and the knowledge based design of other TMPs with crystallizable controlling units. Cambridge Royal Society of Chemistry 2015 10 Journal of materials chemistry : A, Materials for energy and sustainability 3 16 8284 8293 10.1039/c4ta06586g Institut für Chemie