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Interactions in solutions and gels of stimuli-responsive polymer systems investigated by NMR spectroscopy
Konefał, Rafał ; Spěváček, Jiří (advisor) ; Hrabal, Richard (referee) ; Štěpánek, Miroslav (referee)
Stimuli-responsive (stimuli-sensitive, intelligent, or smart) polymers are polymer materials which, after small external stimuli, evidently change their physical or chemical properties. Smart polymers can be classified according stimuli they respond to such as: temperature changes, mechanical stress, light irradiation, ultrasonic treatment, application of external magnetic as well as electric field, changes of pH, ionic strength, addition of the chemical agents and presence of biomolecules and bioactive molecules. Stimuli-responsive synthetic polymer systems has attracted considerable attention due to wide range of applications, i.e. controlled drug delivery and release systems, diagnostics, tissue engineering and 'smart' optical systems, as well as biosensors, microelectromechanical systems, coatings, and textiles. Among the types of stimuli for this dissertation temperature, pH and reactive oxygen species (ROS) responsive polymer systems were studied. In case of thermoresponsive polymers, when polymer chains are molecularly dissolved in a good solvent, changes (increasing or decreasing) of temperature result in insolubility (globular nanoparticles formation) of polymer chains, called temperature induced phase-separation. pH responsive polymers change properties such as: solubility, volume (gels),...
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Investigation of external stimuli-influenced temperature-sensitive polymers behavior studied by spectroscopic methods
Velychkivska, Nadiia ; Starovoytova, Larisa (advisor) ; Lang, Jan (referee) ; Poterya, Viktoriya (referee)
Temperature-sensitive polymers or "smart" polymers are materials that undergo phase separation initiated by temperature change. Some of these polymers possess phase separation temperatures close to human body temperature (37 C), thus offering a wide range of potential applications in controlled drug release or gene delivery systems, bioseparations, tissue engineering, etc. Of the polymers with a phase separation temperature close to 37 C, poly(N- isopropylacrylamide) (PNIPAM) and poly(vinyl methyl ether) (PVME) are perhaps the most important and were selected as the subjects of this study. In this work, these two polymers have been examined in the presence of low molecular weight additives, and their colloidal stability evaluated using 1 H NMR (nuclear magnetic resonance) and time-resolved 1 H NMR spin-spin relaxation time T2 experiments. An improved model of the two exchangeable states was applied for a more detailed characterization of the phase separation process. The main focus of this study was to determine the influence of additives on the phase separation behavior of the polymers (phase separation temperature, width of transition, maximum number of polymer chains participating in phase separation), reversibility of the phase separation, dynamics of solvent molecules (water and additive),...
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Interactions in solutions and gels of stimuli-responsive polymer systems investigated by NMR spectroscopy
Konefał, Rafał ; Spěváček, Jiří (advisor) ; Hrabal, Richard (referee) ; Štěpánek, Miroslav (referee)
Stimuli-responsive (stimuli-sensitive, intelligent, or smart) polymers are polymer materials which, after small external stimuli, evidently change their physical or chemical properties. Smart polymers can be classified according stimuli they respond to such as: temperature changes, mechanical stress, light irradiation, ultrasonic treatment, application of external magnetic as well as electric field, changes of pH, ionic strength, addition of the chemical agents and presence of biomolecules and bioactive molecules. Stimuli-responsive synthetic polymer systems has attracted considerable attention due to wide range of applications, i.e. controlled drug delivery and release systems, diagnostics, tissue engineering and 'smart' optical systems, as well as biosensors, microelectromechanical systems, coatings, and textiles. Among the types of stimuli for this dissertation temperature, pH and reactive oxygen species (ROS) responsive polymer systems were studied. In case of thermoresponsive polymers, when polymer chains are molecularly dissolved in a good solvent, changes (increasing or decreasing) of temperature result in insolubility (globular nanoparticles formation) of polymer chains, called temperature induced phase-separation. pH responsive polymers change properties such as: solubility, volume (gels),...
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