Tailoring of structure of plasma polymers

The thesis was targeted on the preparation of thin film plasma polymers with Plasma assisted vapour thermal deposition technique. As a characterised precursor was chosen the poly lactic acid because of its interesting biodegradable properties. The set of samples prepared with varying plasma power was obtained. It was found that the PLA structure is still preserved after repolymerisation, moreover, new carbon rich compound was formed. The strong changes of behaviour of samples in water were observed around plasma power of 30 W. The sample prepared in weaker plasma had properties of hydrogel. The samples prepared above 30 W of plasma power were solid and did not dissolve in water.Diplomová práce cílila na přípravu tenkých vrstev plasmových polymerů technikou plazmově asistované termální depozice. Jako charakterizovaný prekurzor byla vybrána kyselina polymléčná pro své zajímavé biodegradabilní vlastnosti. Vzorky byly připraveny za různých výkonů plazmatu. Bylo zjištěno, že struktura kyseliny polymléčné je po repolymerizaci zachována a nadto vzniká složka bohatá na uhlík. Vzorky připravené za různých výkonů plazmatu vykazovali velice rozdílné vlastnosti po ponoření do vody. Byly naměřeny velké změny vlastností připravených vrstev po ponoření do vody. Vrstvy připravené při výkonech menších než 30 W vykazovali charakter hydrogelu. Vzorky připravené za vyšších výkonů byly kompaktní a ve vodě se nerozpustilyKatedra makromolekulární fyzikyDepartment of Macromolecular PhysicsFaculty of Mathematics and PhysicsMatematicko-fyzikální fakult

Degradable poly(ethylene oxide)-like plasma polymer films used for the controlled release of nisin

Poly(ethylene oxide) (PEO)-like thin films were successfully prepared by plasma-assisted vapor thermal deposition (PAVTD). PEO powders with a molar weight (Mw) between 1500 g/mol and 600,000 g/mol were used as bulk precursors. The effect of Mw on the structural and surface properties was analyzed for PEO films prepared at a lower plasma power. Fourier transform (FTIR-ATR) spectroscopy showed that the molecular structure was well preserved regardless of the Mw of the precursors. The stronger impact of the process conditions (the presence/absence of plasma) was proved. Molecular weight polydispersity, as well as wettability, increased in the samples prepared at 5 W. The influence of deposition plasma power (0-30 W) on solubility and permeation properties was evaluated for a bulk precursor of Mw 1500 g/mol. The rate of thickness loss after immersion in water was found to be tunable in this way, with the films prepared at the highest plasma power showing higher stability. The effect of plasma power deposition conditions was also shown during the permeability study. Prepared PEO films were used as a cover, and permeation layers for biologically active nisin molecule and a controlled release of this bacteriocin into water was achieved. © 2020 by the authors.Czech Science FoundationGrant Agency of the Czech Republic [GA17-10813S]; TBU in Zlin [IGA/CPS/2020/001

Polyester urethane (PLA/PEG) polymer based films prepared by plasma assisted vapour thermal deposition

Polyester urethane polymer was synthesized as linked biocompatible poly (lactide)/poly (ethylene oxide) polymers. The bulk polymer was subsequently used as precursor material for plasma assisted vapour thermal deposition of thin plasma polymer films under varying RF discharge power. The effect of plasma polymerization on the final physico-chemical characteristics was investigated. The chemical analysis of the films was performed using X-ray photoelectron spectroscopy and infrared spectroscopy. Structural analysis of plasma polymer thin film revealed the similar molecular structure as in case of precursor since PEU-characteristic bonds were preserved after the plasma polymerization. Surface properties analysed by a contact angle measurement revealed an increase of wettability in the samples prepared at higher RF power. At the same time a surface energy evaluated according to acid-base model decreased. The results indicate that plasma polymer films properties could be tuned depending on applied deposition conditions. © NANOCON 2019.All right reserved.Czech Science FoundationGrant Agency of the Czech Republic [GA17-10813S

Structure of plasma (re)polymerized polylactic acid films fabricated by plasma-assisted vapour thermal deposition

Plasma polymer films typically consist of very short fragments of the precursor molecules. That rather limits the applicability of most plasma polymerisation/plasma-enhanced chemical vapour deposition (PECVD) processes in cases where retention of longer molecular structures is desirable. Plasma-assisted vapour thermal deposition (PAVTD) circumvents this limitation by using a classical bulk polymer as a high molecular weight “precursor”. As a model polymer in this study, polylactic acid (PLA) has been used. The resulting PLA-like films were characterised mostly by X-ray photoelectron spectroscopy (XPS) and nuclear magnetic resonance (NMR) spectroscopy. The molecular structure of the films was found to be tunable in a broad range: from the structures very similar to bulk PLA polymer to structures that are more typical for films prepared using PECVD. In all cases, PLA-like groups are at least partially preserved. A simplified model of the PAVTD process chemistry was proposed and found to describe well the observed composition of the films. The structure of the PLA-like films demonstrates the ability of plasma-assisted vapour thermal deposition to bridge the typical gap between the classical and plasma polymers. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Czech Science FoundationGrant Agency of the Czech Republic [GA17-10813S]; Charles University [SVV 260 579-2020]Univerzita Karlova v Praze, UK; Grantová Agentura České Republiky, GA ČR: GA17-10813

Nanostructured films of plasma polymerized hexamethyldisilazane and lactic acid deposited by atmospheric plasma JET

In this work, composite layers of hexamethyldisilazane (HMDSN) and lactic acid (LA) were prepared using chemical vapor deposition process by a nitrogen atmospheric pressure plasma jet source. The HMDSN vapours were introduced into the plasma jet. Varying LA admixture was added into the jet in the form of aerosol. The chemical composition, morphology and wettability of resulting films were studied. Infrared spectra and XPS analysis show both Si-O like and hydrocarbon structures. With increasing amount of LA admixture, the oxidation of the layers increases. The morphology of the films was measured with SEM. The films prepared with no LA have a foam-like structure. With increasing amount of LA the structure changes into more fractal-like. The X-ray diffraction analysis suggests the presence of amorphous SiO2 domains in the films. The films exhibited superhydrophobic properties that can be modified by the post-treatment of the samples in DBD discharge. © NANOCON 2019.All right reserved.Czech Science FoundationGrant Agency of the Czech Republic [17-10813S

Plasma polymers as targets for laser-driven proton-boron fusion

Laser-driven proton-boron (pB) fusion has been gaining significant interest for energetic alpha particles production because of its neutron-less nature. This approach requires the use of B- and H-rich materials as targets, and common practice is the use of BN and conventional polymers. In this work, we chose plasma-assisted vapour phase deposition to prepare films of oligoethylenes (plasma polymers) on Boron Nitride BN substrates as an advanced alternative. The r.f. power delivered to the plasma was varied between 0 and 50 W to produce coatings with different crosslink density and hydrogen content, while maintaining the constant thickness of 1 μm. The chemical composition, including the hydrogen concentration, was investigated using XPS and RBS/ERDA, whereas the surface topography was analyzed using SEM and AFM. We triggered the pB nuclear fusion reaction focusing laser pulses from two different systems (i.e., the TARANIS multi-TW laser at the Queen’s University Belfast (United Kingdom) and the PERLA B 10-GW laser system at the HiLASE center in Prague (Czech Republic)) directly onto these targets. We achieved a yield up to 108 and 104 alpha particles/sr using the TARANIS and PERLA B lasers, respectively. Radiative-hydrodynamic and particle-in-cell PIC simulations were performed to understand the laser-target interaction and retrieve the energy spectra of the protons. The nuclear collisional algorithm implemented in the WarpX PIC code was used to identify the region where pB fusion occurs. Taken together, the results suggest a complex relationship between the hydrogen content, target morphology, and structure of the plasma polymer, which play a crucial role in laser absorption, target expansion, proton acceleration and ultimately nuclear fusion reactions in the plasma

Temperature changes in thin films of nanoparticles

Many properties of nanoparticles are different from general bulk properties. This work is focused on coalescence of nanoparticles depending on temperature.Coalsescence was experimentaly measuered on gold nanoparticles, copper nanoparticles and silver nano- islands.The samples were characterised by SEM, AFM and in-situ ellipsometry in range between 20řC and 350 řC. In the theoretical part was analyzed existing semi-analytical model of coalescence and then it was created a new model based on previous one. In the end, the comparison between experimental data and model was done. New model predicts greater coalescence of nanoparticles, what corresponds to experimental data

Tailoring of structure of plasma polymers

The thesis was targeted on the preparation of thin film plasma polymers with Plasma assisted vapour thermal deposition technique. As a characterised precursor was chosen the poly lactic acid because of its interesting biodegradable properties. The set of samples prepared with varying plasma power was obtained. It was found that the PLA structure is still preserved after repolymerisation, moreover, new carbon rich compound was formed. The strong changes of behaviour of samples in water were observed around plasma power of 30 W. The sample prepared in weaker plasma had properties of hydrogel. The samples prepared above 30 W of plasma power were solid and did not dissolve in water

Temperature changes in thin films of nanoparticles

Many properties of nanoparticles are different from general bulk properties. This work is focused on coalescence of nanoparticles depending on temperature.Coalsescence was experimentaly measuered on gold nanoparticles, copper nanoparticles and silver nano- islands.The samples were characterised by SEM, AFM and in-situ ellipsometry in range between 20řC and 350 řC. In the theoretical part was analyzed existing semi-analytical model of coalescence and then it was created a new model based on previous one. In the end, the comparison between experimental data and model was done. New model predicts greater coalescence of nanoparticles, what corresponds to experimental data.Mnohé vlastnosti nanočástic jsou velmi odlišné od "bulk" materiálu. V mé práci jsem se zabýval sléváním nanočástic, které je závislé na teplotě. Experimentálně bylo proměřeno slévání zlatých nanočástic, měděných nanočástic a stříbrných nanoostrůvků. Experimenty byly charakterizovány pomocí SEM, AFM a in-situ elipsometrie v rozsahu teplot od 20řC do 350řC. V teoretické části byl realizován existující polo-analytický model slévání a následně byl vytvořen nový model vycházející z původního. Nakonec bylo provedeno srovnání experimentu s modely. Upravený model předpovídá větší slévání nanočástic, což je v lepším souladu s experimentem.Katedra makromolekulární fyzikyDepartment of Macromolecular PhysicsFaculty of Mathematics and PhysicsMatematicko-fyzikální fakult