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Polymer hydrogels: heterogeneous structure and deformation behaviour
Karpushkin, Evgenyi ; Dušková - Smrčková, Miroslava (advisor) ; Rypáček, František (referee) ; Kuta, Antonín (referee)
Title: Polymer hydrogels: heterogeneous structure and deformation behavior Author: Evgeny Karpushkin Department: Department of Macromolecular Physics, Faculty of Mathematics and Physics, Charles University in Prague Supervisor: Miroslava Dušková-Smrčková Ing. Dr., Institute of Macromolecular Chemistry AS CR, Heyrovského náměstí 2, 162 06 Prague 6 Abstract: Model series of crosslinked poly(2-hydroxyethyl methacrylate) hydrogels differing in morphology were prepared by polymerization-induced phase separation. Morphology, swelling and dynamic mechanical properties in broad frequency range of the model gels were tested. The vitrification of gels was found sensitive to microstructure of polymer network and to solvent content and to polymer-solvent interaction, but not to the macroscopic morphology of the gel. The low-frequency mechanical response was found sensitive to both polymer network properties and hydrogel morphology. Lightly crosslinked hydrogels showed relatively high mechanical losses in the rubbery plateau region, due to physical association of chains. Fused-particles type hydrogels revealed a weak secondary relaxation at low frequency, ascribed to motion of the dangling particles aggregates. These aggregates, elastically inactive, along with inhomogeneous stress field arisen in porous material, were...
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Characterization of ultra-thin polymer films on solid substrates using different physical techniques
Pop-Georgievski, Ognen ; Rypáček, František (advisor) ; Adam, Pavel (referee) ; Werner, Carsten (referee)
The presented doctoral research was aimed at preparation and characterization of ultra thin polymer films on solid substrates using different physical techniques. Each of these physical techniques probes selectively different characteristics of the films. While some of the techniques are strong in the predetermination of some unique properties of the layers, they might be limited and give no specific/conclusive information about some other important characteristics. Therefore, only the combination of the techniques provides a profound picture of the thickness, architecture, composition and functionality of the films/layers. This combined characterization approach elucidates in details the physical characteristics and the mechanisms responsible for the unique behavior of different polymer films/layers in the application that they are intended for. In the thesis, of particular interest were films of high biomedical, biotechnological and tissue engineering importance, such as: 1. poly(lactide) films formed by grafting "from-" a silanized alacrite thin films (L605 Co-based super alloy), 2. polydopamine (PDA) films that could serve as substrate independent mod- ification platform for further surface modification steps, 3. poly(ethylene oxide)films formed by "grafting to-" PDA modified surfaces, 4....
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Polymer hydrogels: heterogeneous structure and deformation behaviour
Karpushkin, Evgenyi ; Dušková - Smrčková, Miroslava (advisor) ; Rypáček, František (referee) ; Kuta, Antonín (referee)
Title: Polymer hydrogels: heterogeneous structure and deformation behavior Author: Evgeny Karpushkin Department: Department of Macromolecular Physics, Faculty of Mathematics and Physics, Charles University in Prague Supervisor: Miroslava Dušková-Smrčková Ing. Dr., Institute of Macromolecular Chemistry AS CR, Heyrovského náměstí 2, 162 06 Prague 6 Abstract: Model series of crosslinked poly(2-hydroxyethyl methacrylate) hydrogels differing in morphology were prepared by polymerization-induced phase separation. Morphology, swelling and dynamic mechanical properties in broad frequency range of the model gels were tested. The vitrification of gels was found sensitive to microstructure of polymer network and to solvent content and to polymer-solvent interaction, but not to the macroscopic morphology of the gel. The low-frequency mechanical response was found sensitive to both polymer network properties and hydrogel morphology. Lightly crosslinked hydrogels showed relatively high mechanical losses in the rubbery plateau region, due to physical association of chains. Fused-particles type hydrogels revealed a weak secondary relaxation at low frequency, ascribed to motion of the dangling particles aggregates. These aggregates, elastically inactive, along with inhomogeneous stress field arisen in porous material, were...
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Characterization of ultra-thin polymer films on solid substrates using different physical techniques
Pop-Georgievski, Ognen ; Rypáček, František (advisor) ; Adam, Pavel (referee) ; Werner, Carsten (referee)
The presented doctoral research was aimed at preparation and characterization of ultra thin polymer films on solid substrates using different physical techniques. Each of these physical techniques probes selectively different characteristics of the films. While some of the techniques are strong in the predetermination of some unique properties of the layers, they might be limited and give no specific/conclusive information about some other important characteristics. Therefore, only the combination of the techniques provides a profound picture of the thickness, architecture, composition and functionality of the films/layers. This combined characterization approach elucidates in details the physical characteristics and the mechanisms responsible for the unique behavior of different polymer films/layers in the application that they are intended for. In the thesis, of particular interest were films of high biomedical, biotechnological and tissue engineering importance, such as: 1. poly(lactide) films formed by grafting "from-" a silanized alacrite thin films (L605 Co-based super alloy), 2. polydopamine (PDA) films that could serve as substrate independent mod- ification platform for further surface modification steps, 3. poly(ethylene oxide)films formed by "grafting to-" PDA modified surfaces, 4....
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Ultrathin nanofibrous membranes with enhanced properties for transplantation of retinal pigment epithelial cells
Studenovská, Hana ; Popelka, Štěpán ; Abelová, Lucie ; Riedel, Tomáš ; Studený, P. ; Straňák, Z. ; Klíma, Jiří ; Ardan, Taras ; Dvořánková, B. ; Rypáček, František
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Rastrovací elektronová mikroskopie mokrých vzorků syntetických polymerů
Šlouf, Miroslav ; Studenovská, Hana ; Rypáček, František ; Sikora, Antonín
Synthetic polymers with high content of water (wet synthetic polymers,hydrogels) are frequently used in tissue engineering. Investigation of their 3D-structure by means of scanning electron microscopy is very difficult: in a standard electron microscope water almost immediately evaporates and the structure breaks down. Nevertheless, hydrogels morphology can be visualised by means of low-vacuum scanning electron microscopy in cryo conditions (cryoLVSEM) and by environmental scanning electron microscopy (ESEM). The two techniques are described and compared.
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