|
|
Effect of perfluoroalkyl substituents onthe formation and costitutional dynamics of Schiff bases
Štrympl, Ondřej ; Vohlídal, Jiří (advisor) ; Jindřich, Jindřich (referee)
New synthetic routes were designed and applied for novel bisperfluoroalkylated benzene derivatives: 2,5-bis(perfluorooctyl)benzene-1,4-dicarbaldehyde, its dimethylacetal and 2,5- bis(trifluoromethyl)benzene-1,4-diamine. Methods for purification of those derivatives were developed and used to obtain pure crystalline compounds. Crystals of the mentioned diamine and diacetal were obtained in quality suitable for RTG analysis while crystals of dialdehyde were of sufficient quality. New synthesis and purification protocol was designed for 2,5-bis(trifluoromethyl)benzene- 1,4-dialdehyde yielding sufficiently pure product, although isolated amounts are rather small ( yields about 20%) . 2,5-diiodobenzene-1,4-diamine was synthetised. It should be possible to prepare 2,5- bis(perfluorooktyl)benzene-1,4-diamine from this compound either by direct or indirect approach. Nevertheless, the syntheses were yet unsuccessful. A series of eight Schiff bases derived from 3,5-bistrifluoromethylated benzeneamine, benzylamine and benzaldehyde, and three reference bases based on thiophene-2-carbadehyde, benzaldehyde and phenylacetaldehyde was prepared. Kinetics of those species' formation in CDCl3 (all reactions run without catalyst) and THF (necessity of catalysis and susceptibility of equilibria to water) were studied. The...
|
|
| |
|
| |
|
|
Novel conjugated polymers of the metallo-supramolecular and polyelectrolyte class
Hladysh, Sviatoslav ; Vohlídal, Jiří (advisor) ; Strachota, Adam (referee) ; Jindřich, Jindřich (referee)
This thesis targets the development of conjugated polymers with improved process ability from solutions. Two types of ionic polymers are addressed: (i) conjugated metallo-supramolecular polymers (MSPs) composed of conjugated heteroaromatic unimers (building blocks) linked to chains by various metal ions giving charged main chains, and (ii) polythiophene polyelectrolytes containing ionic pendants. Processing advantages of conjugated polyelectrolytes consist in the possibility of their processing from solutions in green solvents such as alcohols or even water. The advantages of MSPs consist in the thermodynamic control of the degree of polymerization (length) of their chains in solutions by the choice of solvent and temperature. As a result, MSPs reversibly provide systems of low viscosity that can be processed from solutions more easily than high-molar-mass polymers giving highly viscous solutions. Synthesis of appropriately designed unimer(s) is the key step of preparation of an MSP. Within this thesis, a series of novel unimers composed of linear oligothiophene type (mono-, bi-, ter- a thieno-thiophene- diyl) central blocks capped with 2,6-bis(oxazoline-2-yl)pyridine (pybox) or 2,6-bis(imidazole-2-...
|
|
|
Control of the morphology of biodegradable polymer blends
Ostafińska, Aleksandra ; Šlouf, Miroslav (advisor) ; Kosek, Juraj (referee) ; Vohlídal, Jiří (referee)
This dissertation, entitled »Control of the morphology of biodegradable polymer blends«, has been running parallel with the grant project »Multiphase biodegradable polymer systems« and it represents a new research direction in the Department of morphology and rheology of polymer materials at the Institute of Macromolecular Chemistry. The main idea was to employ our long-lasting work and experience in the field of morphology control of synthetic polymer blends in the very analogous field of the biodegradable polymer blends. We have chosen three most common, widely used and relatively cheap bio-based polymers - starch, poly(lactic acid) and poly(ε-caprolactone) - in order to investigate how the properties of their blends might be improved if we control the blend morphology in targeted, reproducible and well-defined way from the very beginning. It has been well established that morphology (phase structure, supramolecular structure) is one of the key factors influencing final properties of polymer blends, including mechanical performance, rate of (bio)degradation, gas permeability etc. In this work, numerous preliminary experiments showed that there are two systems in which the morphology control could significantly help in the improving of their end-use properties: PLA/PCL/TiX (where PLA = poly(lactic acid),...
|
|
|
Synthesis and properties of supramolecular polymers
Vitvarová, Tereza ; Vohlídal, Jiří (advisor) ; Jindřich, Jindřich (referee) ; Royal, Guy (referee)
New π-conjugated building blocks (unimers) for metallo-supramolecular polymers (MSPs), whose comprise: (i) substituted phosphole ring surrounded by two thiophene rings as the central block, (ii) 2,2':6',2''-terpyridine-4'-yl (tpy) end-groups as ion-selectors, and (iii) different linkers inserted between the central block and tpy end-groups, are described. Chemical and physical properties of those unimers were studied with attention on correlation between properties and structure of unimers. For example the unimer without linkers shows the UV/vis absorption maximum red shifted about 60 to 100 nm compared to bis(tpy)terthiophenes, which proves that replacing of the thiophene with phosphole unit significantly enhances the delocalization of electrons within the unimer molecule and significant area of absorption spectra can be covered. Introduction of linkers (ethynediyl, ethynediyl-thiophene-2,5-diyl, ethynediyl-1,4-phenylene) has a minor effect on the bandgap energy. All prepared unimers underwent self-assembling process with various metal ions (Co2+ , Cu2+ , Fe2+ , Ni2+ and Zn2+ ) resulting into metallo-supramolecular polymers. Three stages of the assembly of unimers into related MSPs were observed and characterized by absorption, fluorescence spectroscopy and size exclusion chromatography: 1)...
|
|
|
Synthesis and characterization of new polymers of substituted acetylenes
Sivkova, Radoslava Parusheva ; Vohlídal, Jiří (advisor) ; Strachota, Adam (referee) ; Sedlařík, Vladimír (referee)
New procedures for preparation of polyacetylenes with highly luminescent naphthalimide groups that might be potentially utilized in optoelectronics and sensors are developed within the framework of present doctoral thesis. The procedures provide luminescent a) linear polyacetylenes that can be processed from solutions, and b) mesoporous network polyacetylenes with high pore volume. Two paths to soluble polyacetylenes are used: (i) copolymerization of ethynyl- functionalized naphthalimide (monomer PN) and a monoethynyl aromate catalyzed with [Rh(nbd)acac], and (ii) modification of poly(disubstituted acetylene)s carrying -chloroalkyl pendants involving the exchange of chlorine atoms for azido groups and subsequent "click"- reaction of Huisgen type of azido groups with ethynyl groups of PN. The PN does not homopolymerize but copolymerizes with ethynylaromates. The highest possible molar fraction of the PN units in copolymers is of 0.5, which suggests the absence of PN dyads or longer sequences in copolymers and the alternating arrangement of PN units in the copolymers of the composition of 0.5. Surprisingly, ethynylarenes that give insoluble homopolymers gave soluble copolymers with PN. The modification procedure requires knowledge on the effect of the monomer structure symmetry and substituent...
|
|
|
Ruthenium alkylidenes immobilized on mesoporous molecular sieves as catalysts for olefin metathesis
Shinde, Tushar Raghunath ; Balcar, Hynek (advisor) ; Vohlídal, Jiří (referee) ; Kvíčala, Jaroslav (referee)
The main emphasis of the dissertation focuses on the preparation of new heterogeneous metathesis catalysts, their characterization, and testing their activity and selectivity in different metathesis reactions. This work has been completed at the Department of Synthesis and Catalysis, J. Heyrovský Institute of Physical Chemistry, AS CR. Hoveyda-Grubbs type catalyst ZC (Zhan catalyst 1-B) was immobilized on mesoporous molecular sieves of different architecture and pore diameter, d, (hexagonal: MCM-41, d = 4.0 nm; SBA-15, d = 6.8 nm; SBA-15 large pore (LP), d = 11.1 nm and cubic: MCM-48, d = 6.0 nm) and conventional silica (Merck) for comparison. The immobilization was done by simple mixing of ZC solution with appropriate support at room temperature. Ru loading in all immobilized catalyst was 0.93 wt%. The catalysts and supports were characterized by X-ray diffraction and nitrogen adsorption measurement. XPS and UV-Vis spectroscopic studies of ZC immobilized on SBA-15 (ZC/SBA-15) indicated the attachment of ZC on mesoporous sieve surface by non-covalent interactions. The immobilized catalysts exhibited high activity and 100% selectivity in ring-closing metathesis of diethyl diallylmalonate and 1,7-octadiene, in metathesis of methyl oleate and methyl 10-undecenoate, and in the ring-opening metathesis...
|
|
| |
|
| |
guest ::
RSS feed.