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Substituted polyacetylenes with aldehydic groups: preparation and postpolymerization modification
Zhernakova, Yulia ; Sedláček, Jan (advisor) ; Faukner, Tomáš (referee)
Homopolymerization of 3-ethynylbenzaldehyde, 4-ethynylbenzaldehyde and 1- ethynylbenzene-3,5-dicarbaldehyde and copolymerization of these monomers with phenylacetylene have been studied with the aim to prepare soluble homo and copolymers of polyacetylene type with aldehyde groups in pendants. The Rh(I) complexes have been demonstrated to be efficient catalysts of these polymerizations. The solubility of homopolymers prepared was controlled by the symmetry/non-symmetry of the substitution of pendant phenyl groups of the monomeric units. Non-symmetrically substituted 3-ethynylbenzaldehyde provided soluble homopolymer, on the other hand symmetrically substituted 4-ethynylbenzaldehyde and 1- ethynylbenzene-3,5-dicarbaldehyde gave insoluble homopolymers: the insolubility of these homopolymers most probably reflected a tight packing of symmetrically substituted polymer chains in the solid phase. 3-Ethynylbenzaldehyde, 4-ethynylbenzaldehyde and 1-ethynylbenzene- 3,5-dicarbaldehyde when copolymerized with phenylacetylene yielded soluble binary copolymers with a tuneable composition. The polymerizability of 3-ethynylbenzaldehyde and 1- ethynylbenzene-3,5-dicarbaldehyde was close to that of phenylacetylene. However, 4- ethynylbenzaldehyde exhibited about half the polymerizability than phenylacetylene....
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The Impact of Governance on the Performance of Universities in International Comparison
Sedláček, Jan ; Šaroch, Stanislav (advisor) ; Hnát, Pavel (referee) ; Laboutková, Šárka (referee) ; Kvizda, Martin (referee)
The aim of the dissertation thesis is to give recommendations for higher education governance in the context of the Czech Republic based on the research of the impact of selected aspects of governance on the performance of universities in international comparison. The aspects of governance are the autonomy of a university and the influence of stakeholders on the internal governance of a university. The performance involves education, research and the third mission. The dissertation thesis also applies Goodhart's law on the higher education system. It identifies and classifies unintended side effects caused by inappropriate use of measaruble indicators in regulation. On the basis of findings there are given reccomendations for higher education governance in the Czech Republic.
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Interval timing and spatio-temporal integration
Sedláček, Jan ; Stuchlík, Aleš (advisor) ; Telenský, Petr (referee)
Perception of time-space, its subsequent storage and eventual recall is essential for survivor of the most, currently living organisms. In the higher vertebrates, this process is part of the declarative memory. This work will mainly focus on description of spatio-temporal interaction of these engrams in hippocampus mediated by place cells and newly discovered time cells. This work will also mention with that connected importance and function of time perception. At the end there are described timing strategies that might be acquired by subjects in behavioral tasks.
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Functionalized microporous polymer networks prepared from ethynylarenes
Stahlová, Sabina ; Sedláček, Jan (advisor) ; Etrych, Tomáš (referee) ; Červený, Libor (referee)
The preparation of a new group of functionalized conjugated polymer networks has been described based on spontaneous quaternization polymerization of ethynylpyridines with bis(bromomethyl)arenes. The networks consisted of polyacetylene chains with pyridyl and pyridiniumyl pendants cross-linked with -CH2(arylene)CH2- links. The variation of the ratio of monomer and quaternization agent in the feed modified the ratio of pyridyl and pyridiniumyl groups in the networks (pyridyl/pyridiniumyl ratios from 0 to 1.32). The networks did not exhibit a permanent microporosity that could be confirmed by nitrogen adsorption at 77 K. Nevertheless, all networks were active in capture of CO2 at 293 K (up to 0.73 mmol CO2/g, 750 Torr). It has been hypothesized that CO2 capture reflected formation of a temporary porous texture of the networks through conformational changes of the network segments enabled by the segments mobility at room temperature. The preparation of functionalized conjugated polymer networks with permanent micro/mesoporosity (SBET up to 667 m2 /g) has been described that was based on chain coordination copolymerization of acetylenic monomers. The copolymerization of 1,4-diethynylbenzene or 4,4'-diethynylbiphenyl with mono or diethynylbenzenes bearing NO2 or CH2OH groups has been demonstrated as...
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Conjugated porous polymers derived from diethynylarenes by chain-growth polymerization and polycyclotrimerization
Slováková, Eva ; Sedláček, Jan (advisor) ; Merna, Jan (referee) ; Červený, Libor (referee)
4 ABSTRACT The synthesis has been described yielding a new type of rigid conjugated polymer networks which possess a high content of permanent micropores and macropores and exhibit high surface areas up to 1469 m2/g. The networks have been prepared via chain-growth coordination polymerization catalysed with insertion catalysts based on Rh complexes. This polymerization has been newly applied to bifunctional acetylenic monomers of diethynylarene type (1,4-diethynylbenzene, 1,3-diethynylbenzene and 4,4'-diethynylbiphenyl). The covalent structure of the networks consists of the polyacetylene main chains densely connected by arylene struts. The W and Mo metathesis catalysts have been revealed as inefficient for the synthesis of these networks. The increase in the polymerization temperature and time has been shown to affect positively the content and the diameter (up to 22 nm) of the mesopores in the networks. A mechanism has been proposed that explains the mesopores formation as a result of mutual knitting of small particles of the microporous polymer. The application of emulsion polymerization technique allowed to prepare texturally hierarchical polyacetylene networks possessing interconnected open macropores (diameter up to 4,8 μm) the walls of which exhibited micro/mesoporous texture. It was demonstrated...
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Synthesis of microporous polymer networks with azomethine links
Hašková, Alena ; Sedláček, Jan (advisor) ; Balcar, Hynek (referee)
A series of following Schiff base type monomers with two terminal ethynyl groups and one or two azomethine groups have been synthesized: N-(4-ethynylbenzylidene)(4-ethynylaniline), positional isomers of N,N'-(1,4-phenylene)bis(1-(ethynylphenyl)methanimine) and positional isomers of 1,1'-(1,4-phenylene)bis[(N-ethynylphenyl)methanimine]. These monomers have been successfully polymerized in chain-growth mode with the use of [Rh(NBD)acac] as the coordination catalyst into densely cross-linked polyacetylene networks with micro/mesoporous texture and specific surface in hundreds of m2 /g. The positive correlation between the conversion of ethynyl groups and specific surface area on one hand and the increase in reaction temperature and reaction time on the other side was proven. Varying the composition and architecture of polymerized monomers affected particularly the distribution of micropores and mesopores in the networks. The postpolymerization modification of poly[N-(4-ethynylbenzylidene)(4- ethynylaniline)] network has been performed consisting in a partial releasing the links connecting the linear segments of the network. It was confirmed that despite this modification the network preserved the micro/mesoporous texture.
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Aliphatic polyester-based nanoparticles as drug delivery systems
Jäger, Alessandro ; Štěpánek, Petr (advisor) ; Sedláček, Jan (referee) ; Sikora, Antonín (referee)
Nanoparticles from biodegradable polymers are considered one of the most promising systems for biomedical application as drug delivery systems. Therefore, the synthesis and characterization of a new aliphatic biodegradable copolyester named PBS/PBDL (poly(butylene succinate-co- butylene dilinoleate)) intended to the application as drug delivery system is reported in the thesis. Surfactant-free biodegradable and narrowly distributed, nanosized spherical particles (RH < 60 nm) have been produced from the biodegradable material by applying a single-step nanoprecipitation protocol. The size of the generated polymer nanoparticles (PNPs) could be controlled by adjusting the polymer concentration, the choice of organic solvent, mixing different organic solvents or by changing temperature and ionic strength. By optimizing such parameters sub-100 nm uniform PNPs can be produced through this methodology including the advantage and ability to scale-up production. The nanoparticles structure was characterized in detail by employing a variety of scattering techniques and transmission electron microscopy (TEM). Combined static light scattering (SLS) and dynamic light scattering (DLS) measurements suggested that the nanoparticles comprise a porous core conferring them a non-compact characteristic. Their porosity...
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Preparation of functionalized polyacetylenes with linear and cross-linked architecture
Havelková, Lucie ; Sedláček, Jan (advisor) ; Balcar, Hynek (referee)
The phenylacetylene type monomers with benzene ring substituted with one or two aldehyde groups (besides an ethynyl group) were efficiently polymerized into linear mostly high-molecular-weight polyacetylenes with aldehyde groups in pendants if the complex [Rh(NBD)acac] was used as the polymerization catalyst. To achieve high yield and molecular weight of the polymer the positioning of the aldehyde group to meta position with respect to the ethynyl group was most appropriate. It was confirmed that polyacetylenes with aldehyde groups were modifiable by a reaction with p-toluidine under formation of Schiff base type pendant groups. 1,3-Diethynylbenzenes with various substituents in position 5 on the ring (R = H, F, Cl, Br, HCO, NO2, COOCH3) were efficiently polymerized with [Rh(NBD)acac] catalyst into microporous or micro/mesoporous polyacetylene networks that exhibited specific surface area from 311 to 1146 m2 /g. In the case of the networks with HC=O groups, the positive effect of these groups was confirmed on the capacity of the network in CO2 and methanol vapor capture. The composition and texture of the networks possessing HC=O groups were partly reversibly modifiable in reaction with p-toluidine.
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