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Crystallization of binary polylactide blends and their morphology
Debnáriková, Michaela ; Poláček, Petr (referee) ; Bálková, Radka (advisor)
Master thesis deals with the influence of polyvinylacetate, polycaprolactone, poly(butylene-adipate-co-terephtalate) and talc, ethylenevinylacetate, polyethylene glycol and monosodium citrate on the flow properties, mechanical properties and crystallization ability of PLA. The flow properties were studied using the melt flow index and mechanical properties were studied using a tensile test. The crystallinity was studied by differential scanning calorimetry and on a polarization optical microscope equipped with hot stage. Isothermal crystallization was performed at 95 and 105 °C for 3 h and non-isothermal crystallization was performed with a calorimeter at two cooling rates (1 and 10 °C/min). Upon the isothermal crystallization at 95 °C, the formation of denser crystalline structure was observed and the content of crystalline phase increased in most of the samples. The formation of spherulitic structure was observed at 105 °C in samples with 30 % PVAc, 30 % EVA and PEG. Reducing the cooling rate to 1 °C/min at non-isothermal crystallization had nearly no effect on the crystallization process of the most samples; the content of crystalline phase increased in the samples containing PBAT and PEG, which revealed double melting peak during subsequent heating. The crystalline fraction was the most significantly affected by the addition of PEG. All added polymers except PVAc affected the mechanical properties; PBAT, PCL, EVA and PEG increased the strain and decreased the strength and modulus of elasticity. The samples containing monosodium citrate showed unsatisfactory mechanical properties and could not be measured. The samples containing higher concentration of EVA copolymer showed the phase separation.
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Comparison of various amination methods of polycaprolactone concerning their effectivity in tissue engineering
Kováč, Ján ; Lehocký, Marián (referee) ; Zajíčková, Lenka (advisor)
This diploma thesis dealt with the comparison of different methods of amination of polycaprolcatone in terms of their effectiveness for tissue engineering. A polycaprolactone membrane was prepared by an electrospinning method, which was subsequently modified by three different amination methods. Selected types of amination were plasma polymerization with cyclopropylamine monomer, hybrid modification using plasma and N-allylmethylamine monomer, and chemical amination using aminolysis with diaminohexane. Surface amines were subsequently characterized by electron scanning microscopy (SEM), X-ray photoelectron spectroscopy (XPS), attenuated total reflection infrared spectroscopy (ATR-FTIR) and contact angle measurement. A cell culture designated A375 (Human malignant melanoma cell lines A375® CRL-1619®) was cultured on the thus modified membranes, which was analyzed by optical microscopy, and a proliferation assay was performed by determining the relative amount of ATP. Based on the experimental results, we can confirm the success for all types of amination. In terms of efficiency for tissue engineering, the amination method by plasma polymerization with the monomer cyclopropylamine has the most satisfactory results.
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Surface treatment of biocompatible materials
Kováč, Ján ; Kučera, František (referee) ; Krčma, František (advisor)
This bachelor thesis deals with the study of the influence of plasma discharge on changes in the surface properties of the biomaterial. Surface treatements were performed using three types of plasma discharge: gliding arc, dielectric barrier discharge (DBD) and microwave surface wave discharge. Various gaseous mixtures in plasma discharges and their effect on the surface treatment of the biomaterial were investigated. The selected biomaterial was aliphatic biopolymer polycaprolactone (PCL). It is a suitable surface treatment material, thanks to its biodegradability and easy processability. The PCL supplied by Sigma-Aldrich was in the form of pellets, witch had been converted to foil. The film samples were subsequentely exposed to plasma discharges. To characterize the surface properties of the polymer, surface energy was measured using a sissle drop method, a See System from Advex Instrumnets was used to measure. Based on experimental results, we can confirm that the surface has been modified. However, the plasma discharge modifications have led to hydrophilic and not hydrophobic properties of the biomaterial, with the best results in terms of hydrophilicity being achieved by microwave discharge with surface wave. Due to the negative results of the experiment, bactericidal effects were not investigated.
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Electrospinning of Modified Biopolymers for Medical Applications
Pavliňáková, Veronika ; Martinová,, Lenka (referee) ; Zajíčková, Lenka (referee) ; Vojtová, Lucy (advisor)
Předkládaná disertační práce se zabývá přípravou a charakterizací nových biokompatibilních nanovláken s potenciální aplikací v medicíně. V této práci byl výběr jednotlivých složek pro přípravu nanovlákenného materiálu zvolen tak, aby vyhovoval nárokům tkáňového inženýrství. Literární rešerše shrnuje poznatky o elektrostatickém zvlákňování a o jeho parametrech. Dále se věnuje možnostem elektrostatického zvlákňování proteinů kolagenu a želatiny a jejich směsmi se syntetickými polymery a biopolymery a anorganickými plnivy. Teoretická část řeší také různé postupy síťování nanovláken vedoucí ke zlepšení jejich hydrolytické stability a mechanických vlastností. Poslední část je zaměřena na anorganické nanotrubky halloysitu (HNT), které získaly svou pozornost díky svým vynikajícím fyzikálním a biologickým vlastnostem. V experimentální části byly zpracovány dvě případové studie, z nichž každá se zabývá přípravou nanovlákenných biomateriálů s potenciální aplikací v medicíně. První studie je zaměřena na přípravu a charakterizaci nových hydrolyticky stabilních antibakteriálních želatinových nanovláken modifikovaných pomocí oxidované celulózy. Unikátní inhibiční účinky nanovláken byly testovány na kmenu bakterie Escherichia coli pomocí metody chemické bioluminiscence. Kultivované buňky lidského papilárního adenokacinomu plic prokázaly dobrou adhezi a proliferaci k povrchu nanovláken. Druhá část popisuje vliv zdroje a množství anorganických halloysitových nanotrubek na strukturu a vlastnosti amfifilních nanovláken ze směsi želatiny a syntetického polykaprolaktonu. Přídavek HNT zlepšil tepelnou stabilitu, mechanické vlastnosti (jak tuhost, tak prodloužení) a snížil krystalinitu nanovláken. HNT z různých zdrojů neměl vliv na chování buněk, ale mírně ovlivnil proliferaci a životaschopnost buněk na povrchu nanovláken.
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Polycaprolactone, synthesis, characterization, and degradability
Boháčová, Zdeňka ; Vojtová, Lucy (referee) ; Hermanová, Soňa (advisor)
Presented diploma thesis deals with the study of ring-opening polymerization (ROP) of caprolactone catalyzed by novel organic and organometallic compounds. In the theoretical part of the thesis a summary of polymerization strategies and catalytic/initiators systems for ROP of polyesters is overviewed on the basis of reported background research. In experimental part a series of caprolactone polymerization runs with the view of polymerization conditions (solution/monomer ratio, catalyst/initiator ratio, monomer/initiator ratio and monomer concentration) at the temperature range of 25-70 °C was carried out. The experimental study was focused on catalytic precursors based on organic carbenes (tBuNCH=CHN+tBu)CH Cl- (NHC-tBu) in tetrahydrofuran solution and complex of aluminium{O,O’-[4,5-P(O)Ph2tz]-AlMe2} Ph = phenyl, tz = triazole, (OAlMe2) in chlorobenzene solution. Obtained polymers were precisely characterized by means of 1H NMR spectroscopy (Bruker Avance), Differential scanning calorimetry (TA Instruments Q 2000) and Gel permeation chromatography (Agilent Technologies 1100 series) methods. The microbial degradability of synthesized polymer sample having Mn = 12 kg/mol, Mw/Mn = 2.5 and crystallinity degree of 53 % was examined. The polymer in the form of melt-pressed films and powder form was bacterially aged in Bacillus subtilis (BS) strain inoculated mineral and nutrient media for 42 days. Scanning electron microscopy (SEM) and Confocal laser scanning microscopy (CLSM) confirmed the crack development on the surface of films as the consequence of microbial attack in comparison with unchanged control samples. Moreover, the pink coloration of polymer suspension was observed as the consequence of bacterial activity.
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The Polymerization and Copolymerization of e-caprolactone using Organic and Organometallic Catalysts
Smrčková, Markéta ; Vojtová, Lucy (referee) ; Hermanová, Soňa (advisor)
Aliphatic polyesters due to their both biodegradability and biocompatibility appear as a class of promising candidates for biomaterials. Nevertheless, their utilization in practical biomedical systems relies on reproducible synthesis of defined products with the absence of residual toxics giving rise to undesired immunological response in human host. The literature review aim at reporting on the initiators/catalytic systems and synthetic strategies of polycaprolactone preparation. The experimental objective of this work was to verify the presence of catalytic residues based on organic carbenes and organometallic complexes of aluminium in prepared polyesters. A series of polycaprolactone (PCL) samples was purified by re-precipitation in methanol at -10 °C. The presence of catalytic residues in PCL after each purification step was monitored by 1H NMR (Bruker Avance). The residual amount of aluminium was determined by means of Atomic Absorption Spectrometry (AAS) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS).
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Wheat B-starch based polymeric materials
Kotek, Jiří ; Kruliš, Zdeněk ; Šárka, E.
The contribution is aimed at preparation of a thermoplastic material derived from the wheat B-starch. Two ways have been followed, namely blending of the starch with poly(ε-caprolactone) (PCL) and plasticizing of the starch. In both cases, properties of the materials based on the B-starch are comparable to analogous materials based on the A-starch. The prepared materials have potential application as biodegradable films for agriculture.
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