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Novel embedding resins for 3D-SEM II
Šlouf, Miroslav ; Pavlova, Ewa ; Strachota, Beata ; Strachota, Adam ; Nebesářová, Jana ; Týč, Jiří ; Krzyžánek, Vladislav ; Skoupý, Radim
Research report for Thermo Fisher Scientific s. r. o., based on common project awarded by TA CR (program: National center of competence, TN01000008).
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Nanomaterials based on nano-ion hydrophylic polymer interactions
Mesíková, Soňa ; Matějíček, Pavel (advisor) ; Strachota, Adam (referee)
The Thesis deals with the co-assembly of triblock copolymers poly(2-(N, N, N′, N′-tetramethyl guanidinium)ethyl acrylate)-b-poly(ethylene oxide)-b-poly(2-(N, N, N′, N′-tetramethyl guanidinium)ethyl acrylate), PGEA-PEO-PGEA, and poly(N-isopropylacrylamide)-b- poly(acrylic acid)-b-poly(N-isopropylacrylamide), PNIPAM-PAA-PNIPAM, with anionic boron cluster compounds closo-dodecaborate anion, [B12H12]2- , and [cobalt(3+) bis(1,2- dicarbollide)] anion, COSAN, in aqueous solutions, respectively. Synthesis of PNIPAM-PAA- PNIPAM triblock copolymers was performed. The formation of gels based on electrostatic interactions of cationic blocks of PGEA-PEO-PGEA copolymer with closo-dodecaborate anion and on dihydrogen bonding of neutral PNIPAM blocks of PNIPAM-PEO-PNIPAM with COSAN was investigated. The inner structure of the gels was investigated by scattering techniques and fluorescent spectroscopy. Their mechanical properties were studied by diverse rheology measurements. Influence of lithium and sodium salts on PEO/COSAN complex formation and stability in aqueous solution was also studied.
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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-...
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Synthesis of block copolymers by ring-opening polymerization and post polymerization modification with phenylboronic acid
Dudičová, Dorota ; Uchman, Mariusz Marcin (advisor) ; Strachota, Adam (referee)
This thesis deals with the synthesis of propargyl-functionalized amphiphilic diblock copolymers, poly(ε-caprolactone)-b-poly(ethylene oxide), PgCL-PEO via Ring Opening Polymerization (ROP) using monohydroxyl-terminated PEO block as the macroinitiator and its post polymerization modification via Copper-Catalyzed Azide-Alkyne Click reaction (CuAAC) to introduce phenylboronic acid functionality into block copolymers. A reproducible synthetic protocol was developed for preparation of well-defined functional diblock copolymers. The amphiphilic block copolymers were characterized in terms of molecular weight and dispersity by various techniques: Nuclear Magnetic Resonance (NMR) spectroscopy, Gel Permeation Chromatography (GPC) and Matrix-Assisted Laser Desorption/Ionization Time-of-Flight (MALDI ToF) Mass Spectrometry. Keywords: Amphiphilic block copolymers, CuAAC click, phenylboronic acid, poly-ε- caprolactone, ring-opening polymerization
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Organic-inorganic polymers - synthesis and characterization of hybrid polymers and nanocomposites
Depa, Katarzyna ; Strachota, Adam (advisor) ; Matějka, Libor (referee) ; Sedláček, Jan (referee)
In the first part of this work, silica nanoparticles and alternative or additional filler phases were incorporated into hydrogels based on the temperature-sensitive poly(N- isopropylacrylamide) (PNIPAm). Nano-SiO2-filled porous PNIPAm hydrogels with an enhanced force response (up to 100 g) to temperature stimuli were obtained by increasing several times the pore wall thickness, which was achieved via reducing the solvent (porogen) content during the gels' cryo-synthesis. A similar optimization of the force response was also carried out for analogous gels reinforced by nano-TiO2, in which the reinforcing effect of the filler is weaker. Partial intercalation of amylopectin starch into divinyl-crosslinked bulk as well as porous PNIPAm gels several times improved their extensibility. In case of starch-rich bulk gels, a very fast and extensive one-way deswelling in response to increased temperature was achieved (re-swelling upon cooling is much slower), which is attributed to specific properties of the starch-PNIPAm interface. In doubly-filled bulk PNIPAm/nano-SiO2/starch gels, a very strong synergic reinforcing effect of both fillers is observed, due to specific hydrogen bridging between the three phases. Highly porous cryogels based on PNIPAm/nano- SiO2/starch displayed a highly improved extensibility...
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Self-assembling hybrid nanomaterials
Rodzeń, Krzysztof ; Strachota, Adam (advisor) ; Svoboda, Jan (referee) ; Matějíček, Pavel (referee)
Organic-inorganic polymer hybrids containing butyl stannoxane dodecamer cages (Sn_POSS) as nano-building blocks were prepared and investigated. Sn_POSS was employed as a linear, crosslinking or non-bonding molecularly blended unit. For this purpose, it was synthesized with two acrylamido, primary- or secondary amino, or with two additional non- functional groups, which were attached via ionic-bonded sulfonate substituents. The nano- building block was then incorporated in matrices such as PS, PAOS, PETA, PEMA, PHEMA and PPO-based epoxies (the latter with different mesh sizes). Sn_POSS reinforces the studied matrixes by filler-filler interactions (self-assembly to nano-domains). Specific interactions of the ionic bonds of Sn_POSS with suitable pendant groups of the matrixes also can generate reinforcement and suppress filler aggregation. Moreover, the Sn_POSS can undergo several types of chemical reactions like heat-induced oligomerization, dissociation of the ionic substituents, acidolysis of the Sn-butyl bonds, as well as radical reactions of the latter. The influence of ionically bonded cages on the hybrids' morphology, as well as their ability of dissociation and short-distance migration in the polymer network at elevated temperature, was evaluated by TEM, IR and NMR analyses. The mechanical...
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Preparation and characterization of bis(terpyridyl)fluorene based polymers
Hrma, Martin ; Svoboda, Jan (advisor) ; Strachota, Adam (referee)
The diploma thesis presents the preparation of ,-bisterpyridinylfluorenes (unimers) containing fluorene unit in the central block either directly attached to terpyridine (tpy) end groups or via 1,4-phenylene or thiophene-2,5-diyl linker. Synthesized unimers were subsequently used for the preparation of metallo-supramolecular polymers with Zn2+ and Fe2+ ions. The prepared unimers were characterized by NMR, IR and HR-MS, their optical properties were investigated using absorption and emission spectroscopy and cyclic voltammetry. Molecular weight distribution for the prepared Fe-polymers was determined by GPC. The number-average degree of polymerization equal to 7 for an equimolar ratio between unimer and Fe2+ in a diluted solution was determined for polymers composed of unimer with thiophene-2,5- diyl linker. By using the viscometric measurements the ongoing constitutional dynamics in solutions of metallo-supramolecular polymers was proven. The overstoichiometric amount of metal ions in solution resulted in equilibrium shortening of the polymer chains together with end-capping of terminal tpy ligands by Mt2+ ions. Unimer with thiophene-2,5-diyl linker exhibited unique properties involving significantly red-shifted absorption and emission maxima, as well as the different behavior during assembling...
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Boron cluster compounds as building blocks in supramolecular chemistry
Steiner, Filip ; Matějíček, Pavel (advisor) ; Strachota, Adam (referee)
The aim of this bachelor thesis was to get used to with the basics of boron chemistry, especially the exoskeletal derivatization of boron cluster compounds. Exoskeletal substitution of the closo-dodecaborate anion [B12H12]2- , which proceeds by the electrophile induced nucleophilic substitution (EINS) mechanism, provided a derivative containing a cyclic oxonium ring which was subsequently opened by reaction with alcohols (1-dodecanol, 1-octanol). The prepared compounds were characterized by 1 H, 13 C and 11 B NMR spectroscopy and MALDI-TOF mass spectrometry. The compounds will be used as building blocks for preparation of novel nanostructures via supramolecular chemistry approaches.
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Oriented copolymers with liquid crystalline building blocks
Horodecka, Sabina Jolanta ; Strachota, Adam (advisor) ; Uchman, Mariusz Marcin (referee) ; Sedláková, Zdeňka (referee)
Several series of reversible physical networks based on polydimethylsiloxane (PDMS) chains and liquid crystalline (LC) structural units were synthesized and studied, which belong to three different architecture types: (1) LC-grafted PDMS (with LC quartets at the grafting sites), (2) LC-end-capped linear PDMS, (3) and linear 'infinite' LC-PDMS copolymers (with alternating LC and PDMS segments). PDMS spacers of different lengths of were tested, as well as 6 different polyaromatic mesogens of azo type and azo-free type. Hydrosilylation coupling of vinyl-functional mesogens, obtained as part of an international cooperation, with commercial Si-H-functional PDMS was employed to synthesize all the studied materials. The copolymers were physically crosslinked by the nano-aggregation of the LC units contained in their macromolecules. The thermotropic properties of the LC-nano-aggregates lent interesting physical properties to the whole material, making some of the copolymers attractive as potential smart materials. The PDMS spacer segments were selected for the sake of their extreme flexibility, which should provide elastic properties to the physically crosslinked copolymers, and also because of their (desired) incompatibility with the mesogens. This latter effect was highly helpful for achieving the...
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