|
|
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...
|
|
|
The Study of Dynamic Behaviour and Interactions During the Temperature-Induced Phase Separation in Polymer Solutions
Kouřilová, Hana ; Hanyková, Lenka (advisor) ; Štěpánková, Helena (referee) ; Dušková - Smrčková, Miroslava (referee)
Title: The Study of Dynamic Behaviour and Interactions During the Tempera- ture-Induced Phase Separation in Polymer Solutions Author: Hana Kouřilová Department / Institute: Charles University in Prague, Faculty of Mathemat- ics and Physics, Department of Macromolecular Physics Supervisor of the doctoral thesis: doc. RNDr. Lenka Hanyková, Dr. Abstract: 1 H and 13 C high-resolution NMR spectroscopies were used for the phase separation investigation in three types of polymer solutions: i) poly(N -isopropylmethacrylamide)/D2O/ethanol with or without negatively charged comonomer sodium methacrylate, ii) random copolymers poly(N -isopro- pylmethacrylamide-co-acrylamide) in D2O, D2O/ethanol and D2O/acetone and iii) D2O solutions of polymer mixtures poly(N -isopropylmethacrylamide)/poly(N - vinylcaprolactam). For i) cononsolvency effect and influence of temperature on the phase separation was studied. Differences between mesoglobules formed as a consequence of cononsolvency effect and of temperature were found. While inside the cononsolvency-induced mesoglobules no bound ethanol molecules were detect- ed, in the mesoglobules formed by the effect of temperature ethanol molecules were present. The charge introduced into the polymer chains strenghtens polymer- solvent interactions. For ii) mesoglobules were found to be...
|
|
| |
|
| |
|
|
Microstructure, swelling and deformation behavior of methacrylate hydrogels with interpenetrating network structure
Sadakbayeva, Zhansaya ; Dušková - Smrčková, Miroslava (advisor) ; Hanyková, Lenka (referee) ; Kuta, Antonín (referee)
Title: Microstructure, swelling and deformation behavior of methacrylate hydrogels with interpenetrating network structure Author: Zhansaya Sadakbayeva Department: Department of Macromolecular Physics, Faculty of Mathematics and Physics, Charles University in Prague Supervisor: Ing. Miroslava Dušková-Smrčková, Dr., Institute of Macromolecular Chemistry, Czech Academy of Sciences Consultant: Prof. Ing. Karel Dušek, DrSc., Institute of Macromolecular Chemistry, Czech Academy of Sciences Abstract: This work is devoted to interpenetrating polymer network (IPN) hydrogels prepared by sequential processes of redox-initiated radical polymerization of the first network prepared from 2-hydroxyethyl methacrylate (HEMA), and UV- initiated radical polymerization of the second network prepared from 2-hydroxyethyl methacrylate (HEMA) or glycerol methacrylate (GMA). Microstructure, swelling and deformation responses of the IPN hydrogels and their constituent network hydrogels were tested by various techniques. The microstructure of the first poly(HEMA) network was found sensitive to polymerization conditions. A novel route for one-step synthesis of double-porous poly(HEMA) cryogel was proposed. The formation of the second poly(GMA) network in the environment of non-porous and macroporous poly(HEMA) parent networks was...
|
|
|
Stimuli Responsive Multicomponent Polymer Systems
Šťastná, Julie ; Hanyková, Lenka (advisor) ; Dušková - Smrčková, Miroslava (referee) ; Labuta, Jan (referee)
Title: Stimuli Responsive Multicomponent Polymer Systems Author: Julie Šťastná Department: Charles University in Prague, Faculty of Mathematics and Physics, Department of Macromolecular Physics Supervisor: doc. RNDr. Lenka Hanyková, Dr., Charles University in Prague, Faculty of Mathematics and Physics, Department of Macromolecular Physics Abstract: Combination of 1 H NMR spectroscopy, differential scanning calorime- try (DSC), dynamic mechanical measurement, and optical microscopy was used to investigate temperature-induced phase transition of three types of systems: i) in D2O solutions of poly(N-isopropylmethacrylamide-co-acrylamide) (P(NIPMAm/- AAm)) random copolymers and in interpenetrating networks ii) poly(N-isopropyl- methacrylamide/poly(N-isopropylacrylamide) (PNIPMAm/PNIPAm), and iii) po- ly(vinylcaprolactam)/poly(N-isopropylacrylamide) (PVCL/PNIPAm). In all sys- tems influence of composition of the system on the phase transition was studied. For i) both the NMR and DSC data showed dependence on the acrylamide (AAm) content in the copolymer. NMR data was used to construct van't Hoff plots and changes of the enthalpy ∆H and entropy ∆S were studied. As it follows from comparison of ∆H values for NMR and DSC the size of the domains undergoing the transition as a whole decreases with increasing AAm...
|
|
|
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...
|
|
|
The Study of Dynamic Behaviour and Interactions During the Temperature-Induced Phase Separation in Polymer Solutions
Kouřilová, Hana ; Hanyková, Lenka (advisor) ; Štěpánková, Helena (referee) ; Dušková - Smrčková, Miroslava (referee)
Title: The Study of Dynamic Behaviour and Interactions During the Tempera- ture-Induced Phase Separation in Polymer Solutions Author: Hana Kouřilová Department / Institute: Charles University in Prague, Faculty of Mathemat- ics and Physics, Department of Macromolecular Physics Supervisor of the doctoral thesis: doc. RNDr. Lenka Hanyková, Dr. Abstract: 1 H and 13 C high-resolution NMR spectroscopies were used for the phase separation investigation in three types of polymer solutions: i) poly(N -isopropylmethacrylamide)/D2O/ethanol with or without negatively charged comonomer sodium methacrylate, ii) random copolymers poly(N -isopro- pylmethacrylamide-co-acrylamide) in D2O, D2O/ethanol and D2O/acetone and iii) D2O solutions of polymer mixtures poly(N -isopropylmethacrylamide)/poly(N - vinylcaprolactam). For i) cononsolvency effect and influence of temperature on the phase separation was studied. Differences between mesoglobules formed as a consequence of cononsolvency effect and of temperature were found. While inside the cononsolvency-induced mesoglobules no bound ethanol molecules were detect- ed, in the mesoglobules formed by the effect of temperature ethanol molecules were present. The charge introduced into the polymer chains strenghtens polymer- solvent interactions. For ii) mesoglobules were found to be...
|
|
| |
|
| |
guest ::
RSS feed.