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Zur Darstellung von Edelmetallnanopartikelüberstrukturen werden zunächst kolloidale Lösungen von Gold, Silber, Platin und Palladium synthetisiert. Dafür wird eine modifizierte Syntheseprozedur für Citrat stabilisierte Goldnanopartikel in wässriger Lösung unter Verwendung gleicher Konzentrationen auf die Systeme Silber, Platin und Palladium übertragen. Die Nanopartikellösungen werden mittels Absorptionsspektroskopie und Elektronenmikroskopie in mittlerer und hoher Auflösung charakterisiert. Die Platinnanopartikel werden verwendet, um mittels Keim vermitteltem Wachstum größere Platinnanopartikel darzustellen. Die resultierenden annähernd sphärischen Partikel haben eine sehr enge Größenverteilung mit einer Standardabweichung von drei bis sieben Prozent. Mit bis zu zwei Schritten des Keim vermittelten Wachstums können Partikel mit einem mittleren Durchmesser im Bereich von 10 bis 100 Nanometern hergestellt werden. Hochauflösende Elektronenmikroskopie zeigt, dass die Oberfläche der Partikel aus Platinkristalliten mit Durchmessern weniger Nanometer besteht, was zu einer Oberflächenrauhigkeit von drei bis zehn Nanometern führt. Mittels eines Kern-Schale-Modells werden Einzelteilchenextinktionsspektren berechnet, welche in sehr guter Übereinstimmung mit den experimentell bestimmten Extinktionsspektren des dispergierten Ensembles sind. Eine über weite Bereiche des sichtbaren Spektralbereichs lineare Abhängigkeit des Extinktionsmaximums vom Partikeldurchmesser wird beobachtet. Dadurch und zusammen mit der Einheitlichkeit der synthetisierten Platinsphären eröffnen sich Anwendungsmöglichkeiten im Bereich der Photonik, der Nanooptik und der oberflächenverstärkten Ramanspektroskopie. Geordnete Überstrukturen der Edelmetallnanopartikel können durch Infiltrieren von Templaten aus Block-Copolymer-Filmen mit wässriger Nanopartikellösung synthetisiert werden. In Abhängigkeit von der Vorbehandlung der Polymerfilme werden entweder zweidimensional periodische Anordnungen mit einer Periodizität von weniger als 30 Nanometern oder Fingerabdruck ähnliche Anordnungen mit einem Rillenabstand im selben Größenbereich hergestellt. Durch Entfernen des Polymers entstehen ein- bzw. zweidimensionale Anordnungen aus Platinnanodrähten bzw. -Nanopartikeln auf einem Siliziumwafer. Diese hochgeordneten Strukturen sind von fundamentalem Interesse für die Entwicklung von nanometerskaligen Schaltkreisen, Sensoren und als Substrate für die oberflächenverstärkte Ramanspektroskopie. Für die Herstellung ungeordneter Überstrukturen werden zwei unterschiedliche Ansätze gewählt: direkte Destabilisierung von Nanopartikellösungen, welche zu Hydrogelen und durch Trocknung zu Aerogelen führt, und Immobilisierung von Nanopartikeln auf einem in die Lösung implantierten Pilzmycel. Aus Gold-, Silber- und Platinnanopartikeln werden monometallische Hydro- und Aerogele synthetisiert. Unterschiedliche Destabilisierungsmittel sowie unterschiedliche Methoden zur Aufkonzentration der Nanopartikellösungen werden getestet. Abhängig von der Methode werden gelartige Überstrukturen mit teilweise komplexen Morphologien aus hierarchischen Anordnungen von Primär-, Sekundär-, Tertiärpartikeln beobachtet. Bimetallische Hydro- und Aerogele können aus Mischungen von Gold- oder Platin- mit Silbernanopartikellösungen hergestellt werden. Hochauflösende TEM-Aufnahmen zeigen ein polykristallines Netzwerk aus 2 bis 10 Nanometer dicken Drähten. Erste BET-Messungen zeigen, dass die Gold-Silber-Netzwerke eine Oberfläche von etwa 48 m2/g besitzen. Diese Systeme aus monometallischen und bimetallischen Nanopartikeln stellen erste Ansätze für hochporöse templatfreie Hydro- und Aerogele dar und besitzen großes Potential für den Einsatz in der heterogenen Gasphasenkatalyse, da fast die gesamte Oberfläche aus Übergangsmetall besteht. Es wird für eine Auswahl an unterschiedlichen Pilzen gezeigt, dass deren Wachstum direkt in den synthetisierten Nanopartikellösungen möglich ist. Ohne weitere Funktionalisierung findet eine Anlagerung von Nanopartikeln auf der Pilzoberfläche statt. Starke Variationen in den Affnitäten verschiedener Pilze zu den unterschiedlichen Metallnanopartikeln werden beobachtet. Auch werden Unterschiede der Nanopartikelaffnität mit Variation der Morphologie innerhalb desselben Hybridsystems beobachtet. Ein Platin-Pilz-Hybrid wird in wässriger Lösung erfolgreich als Katalysator einer Redoxreaktion getestet. Solche Hybridstrukturen besitzen ebenso wie die oben beschriebenen Aerogele großes Potential für den Einsatz in der heterogenen Katalyse, wobei die Verwendung von Pilzmycel als Trägermaterial eine kostengünstige Darstellung größerer Katalysatormengen ermöglichen könnte.

Organic materials such as polymer films surround us in many everyday applications ranging from food packaging and smartphone displays to medical purposes. One of their main usage scenarios is the thin, lightweight, and easy processable encapsulation to protect a particular target from molecular oxygen. Hence, the oxygen diffusion properties in these polymer films represent a key parameter. This work demonstrates a new method to determine and model the oxygen distribution in thin polymer films using light. It provides a significant advantage over many common methods since no vacuum machinery is needed. The working principle is based on the phosphorescent emission of an organic dopant which is quenched in the vicinity of molecular oxygen at room temperature. The model system used in this study consists of a polystyrene layer, which is doped with PtOEP (Platin(II)-2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin) and covered with a barrier layer of Ex-cevalTM. The oxygen concentration in the doped polystyrene film can be locally depleted under excitation with 365 nm UV light. To determine the oxygen diffusion coefficient, a concentration gradient is created and the time evolution of the luminescent pattern is recorded with a CCD-camera. The recorded data is reconverted to oxygen concentration equivalents and the impact of photoconsumption during the recording process is eliminated, before fitting it with a diffusion simulation. The result reveals a significant dependency on the processing conditions of the film, i.e. D = (1.49 ± 0.08) × 10−7 cm^2/s for unannealed and D = (0.71 ± 0.09) × 10−7 cm^2/s for an-nealed samples. The values lie well in the range reported in the literature.:Problem Goal Conception The physics behind the phenomenon Results More

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal.

Corrosion protection performance of a completely soluble polyaniline-dodecylbenzenesulfonic acid salt (PANI-DBSA) on C45 steel has been studied with electrochemical impedance and potentiodynamic measurements. Chloroform is the most suitable solvent to process the pristine PANI-DBSA because of negligible interaction of the solvent with the polyaniline (PANI) backbone. An anodic shift in the corrosion potential (<img src="http://scitation.aip.org/stockgif3/Dgr.gif" alt="Delta" align="bottom" border="0"><i>E</i>=~70&nbsp;&nbsp;mV), a decrease in the corrosion current and a significant increase in the charge transfer resistance indicate a significant anti-corrosion performance of the soluble PANI deposited on the protected steel surface. Corrosion protection follows the mechanism of formation of a passive oxide layer on the surface of C45 steel. In situ UV-Vis spectroscopy was used to investigate the differences in permeability of aqueous anions into PANI-DBSA. Preliminary results of electron diffraction studies show that PANI-DBSA possesses an orthorhombic type of crystal structure. An increase in the feed ratio of DBSA to aniline increases the tendency of aggregation of spherical particles of PANI obvious in transmission electron microscopy. PANI-DBSA slowly loses its electrochemical activity in acid free electrolyte without undergoing degradation.

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal

When azobenzene-modified photosensitive polymer films are irradiated with light interference patterns, topographic variations in the film develop that follow the electric field vector distribution resulting in the formation of surface relief grating (SRG). The exact correspondence of the electric field vector orientation in interference pattern in relation to the presence of local topographic minima or maxima of SRG is in general difficult to determine. In my thesis, we have established a systematic procedure to accomplish the correlation between different interference patterns and the topography of SRG. For this, we devise a new setup combining an atomic force microscope and a two-beam interferometer (IIAFM). With this set-up, it is possible to track the topography change in-situ, while at the same time changing polarization and phase of the impinging interference pattern. To validate our results, we have compared two photosensitive materials named in short as PAZO and trimer. This is the first time that an absolute correspondence between the local distribution of electric field vectors of interference pattern and the local topography of the relief grating could be established exhaustively. In addition, using our IIAFM we found that for a certain polarization combination of two orthogonally polarized interfering beams namely SP (↕, ↔) interference pattern, the topography forms SRG with only half the period of the interference patterns. Exploiting this phenomenon we are able to fabricate surface relief structures below diffraction limit with characteristic features measuring only 140 nm, by using far field optics with a wavelength of 491 nm. We have also probed for the stresses induced during the polymer mass transport by placing an ultra-thin gold film on top (5–30 nm). During irradiation, the metal film not only deforms along with the SRG formation, but ruptures in regular and complex manner. The morphology of the cracks differs strongly depending on the electric field distribution in the interference pattern even when the magnitude and the kinetic of the strain are kept constant. This implies a complex local distribution of the opto-mechanical stress along the topography grating. The neutron reflectivity measurements of the metal/polymer interface indicate the penetration of metal layer within the polymer resulting in the formation of bonding layer that confirms the transduction of light induced stresses in the polymer layer to a metal film. / Azobenzolhaltige Polymere gehören zu einer Klasse funktionaler Materialien, bei denen durch ein äußeres Strahlungsfeld eine starke mechanische Reaktion ausgelöst werden kann. Durch die Bindung an das Polymerrückgrat können die Azobenzole, die unter UV-Belichtung eine Photoisomerisierung ausführen, was zum Teil drastische Effekte zur Folge hat. Unter Belichtung mit Intensitätsmustern, d.h. mit räumlich variierender Verteilung der Polarisation oder der Intensität des einfallenden Lichts verändert sich die Topographie der azobenzolhaltigen Filme, was zur Bildung von Oberflächengittern (engl. Surface Relief Gratings, SRG) führt. In dieser Arbeit wurde eine neue Methode vorgeschlagen, bei der das Verhalten elastischer/morphologischer Eigenschaften unter verschiedenen Belichtungsbedingungen, d.h. mit unterschiedlicher Verteilung der Polarisation und der Intensität in situ lokal als Funktion der Position entlang der SRG aufgenommen werden kann. Außerdem wurde hier vorgeschlagen, opto-mechanische Spannungen, die innerhalb der photosensitiven Polymerfilme während der Belichtung entstehen, mit Hilfe dünner aufgebrachter metallischen Schichten abzubilden und zu analysieren.

Artificial lipid bilayers formed on solid surface supports are widespread model systems to study physical, chemical, as well as biological aspects of cell membranes and fundamental interfacial interactions. The approach to use a thin polymer film representing a cushion for lipid bilayers prevents incorporated membrane proteins from pinning to the support and mimics the native environment of a lipid bilayer in certain aspects of the extracellular matrix and intracellular structures. A key component for cell anchorage to extracellular fibronectin is the transmembrane adhesion receptor alpha(5)beta(1) integrin. Its transport dynamics and clustering behavior plays a major role in the assembly of focal adhesions, which mediate mechanical forces and biochemical signals of cells with their surrounding. The system investigated herein is envisioned to use extrinsically controlled stimuli-responsive polymer cushions to tune the frictional drag between polymer cushion and mobile membranes with incorporated integrins to actively regulate lipid membrane characteristics. To attain this goal, a temperature- and pH-responsive polymer based on poly(N-isopropylacrylamide) copolymers containing varying amounts of carboxyl-group-terminated comonomers at different aliphatic spacer lengths (PNIPAAm-co-carboxyAAM) was surface-grafted to a poly(glycidyl methacrylate) anchorage layer. The swelling transitions were characterized using atomic force microscopy, ellipsometry and quartz crystal microbalance with dissipation monitoring (QCM-D) and found to be tunable over a wide range of temperature and pH. In agreement with the behavior of the polymers in solution, longer alkyl spacers decreased the phase transition temperature T(P) and higher contents of carboxylic acid terminated comonomers increased T(P) at alkaline conditions and decreased T(P) at acidic conditions. Remarkably, the point where the degree of carboxyl group deprotonation balances the T(P)-lowering effect of the alkyl spacer was distinctive for each alkyl spacer length. These findings illustrate how the local and global balance of hydrophilic and hydrophobic interactions along the copolymer chain allows to adjust the swelling transition to temperatures below, comparable, or above those observed for PNIPAAm homopolymers. Additionally, it could be shown that surface-grafting leads to a decrease in T(P) for PNIPAAm homopolymers (7°C) and copolymers (5°C - 10°C). The main reason is the increase in local polymer concentration of the swollen film constrained by dense surface anchorage in comparison to the behavior of dilute free chains in solution. In accordance with the Flory-Huggins theory, T(P) decreases with increasing concentration up to the critical concentration. Biological functionalization of the PNIPAAm-co-carboxyAAm thin films was demonstrated for the cell adhesion ligand peptide cRGD via carbodiimide chemistry to mimic extracellular binding sites for the cell adhesion receptors integrin. The outcome of QCM-D measurements of cRGD-functionalized surfaces showed a maintained stimuli-responsiveness with slight reduction in T(P). A drying/rehydration procedure of a 9:1 lipid mixture of the cationic lipid dioleoyl-trimethylammoniumpropane (DOTAP) and the zwitterionic dioleoyl-phosphatidylcholine (DOPC) was utilized to form lipid bilayer membranes on PNIPAAm-co-carboxyAAM cushions. Fluorescence recovery after photobleaching (FRAP) revealed that lipid mobility was distinctively higher (6.3 - 9.6) µm2 s-1 in comparison to solid glass support ((3.0 - 5.9) µm2 s-1). In contradiction to the initial expectations, modulation of temperature and pH led to poor variations in lipid mobility that did not correlate with the PNIPAAm cushion swelling state. The results suggested a weak coupling of the lipid bilayer with PNIPAAm polymer cushions that can be slightly tuned by electrostatic interactions. The transmembrane adhesion receptor alpha(5)beta(1) integrin was reconstituted into liposomes consisting of DOPC/sphingomyelin/cholesterol 2:2:1 for the formation of polymer cushioned bilayers. PNIPAAm- co-carboxyAAM and maleic acid (MA) copolymers were used as cushions, both with the option for cRGD functionalization. On the MA copolymer cushions, fusion of proteoliposomes resulted in supported bilayers with mobile lipids as confirmed by FRAP. However, incorporated integrins were immobile. In an attempt to explain this observation, the medium-sized cytoplasmic integrin domain was accounted to hamper the movement by steric interactions with the underlying polymer chains in conjunction with electrostatic interactions of the cationic cytoplasmic domain with the oppositely charged MA copolymer. On the PNIPAAm-co-carboxyAAM cushion only a drying/rehydration procedure lead to bilayer formation. However, again the integrins were immobile, presumably due to the harsh treatment during preparation. Nevertheless, the results of the investigated set of PNIPAAm copolymer films suggest their application as temperature- and pH-responsive switchable layers to control interfacial phenomena in bio-systems at different physiological conditions. The PNIPAAm-co-carboxyAAm cushioned bilayer system represents a promising step towards extrinsically controlled membrane – substrate interactions.

Submitted by Eliseu Antonio Cavalini null (cavaliniea1356@ig.com.br) on 2017-01-08T01:45:41Z No. of bitstreams: 1 Tese Dout V Final.pdf: 2360887 bytes, checksum: 17f60dc9305936e9dd9ea3744d049148 (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2017-01-11T13:28:41Z (GMT) No. of bitstreams: 1 cavalini_ea_dr_guara.pdf: 2360887 bytes, checksum: 17f60dc9305936e9dd9ea3744d049148 (MD5) / Made available in DSpace on 2017-01-11T13:28:41Z (GMT). No. of bitstreams: 1 cavalini_ea_dr_guara.pdf: 2360887 bytes, checksum: 17f60dc9305936e9dd9ea3744d049148 (MD5) Previous issue date: 2016-12-09 / Plasmas de gases e / ou vapores orgânicos produzem filmes finos ou pós apresentando características poliméricas, especialmente quando os plasmas são derivados de monômeros das famílias dos hidrocarbonetos alcoóis, siloxanos, silazanos, e outro. Neste trabalho, os filmes finos foram obtidos a partir da mistura de ácido cítrico-etilenoglicol-metal complexador depositado a plasma, com 13,56 MHz de radiofrequência na potência de 10 a 50 W e pressão fixada a 10 Pa. Os resultados da análise de espectroscopia de infravermelho FTIR mostrou que os grupos vibracionais dos filmes estavam preservados, mas com modificações em suas estruturas moleculares. Foram observados nos resultados obtidos por espectroscopia fotoelétrica de raios-X modificações na composição química da ligação oxigênio-carbono e oxigênio-hidrogênio com variação da potência de 10 a 50 W. A taxa de deposição dos filmes finos diminuiu de 0,10 a 0,08 nm/minuto com o aumento da potência de 10 a 50 W. As propriedades óticas das amostras como o índice de refração, coeficiente de absorção, gap ótico foram investigados por espectroscopia UV- visível. Destas análises foram possíveis obter valores n de 1,54 a 1,50 e energia do gap entre 4,75 e 4,85 eV. A técnica de ângulos de contato e foi utilizada para investigar a molhabilidade das amostras, que apresentaram caráter hidrofílico em todas as condições de deposição dos filmes. A técnica de EDS foi usada para investigar as composições químicas das amostras. Além disso, os filmes obtidos apresentaram valores de condutividade elétrica superior a 10-8 (Ωcm)-1 e constantes dielétricas entre 2,4 e 2,7. / Plasmas from gases and / or organic vapors produce thin films or powders presenting polymeric characteristics, especially when the plasmas are derived from monomers of the families of hydrocarbons, alcohols, siloxanes, silazanes, and others. In this work, thin films were obtained by citric acid / ethylene glycol / complex metal deposited by 13.56 MHz RF plasma at 10 and 50 W fixed pressure 10 Pa. FTIR spectroscopy showed that the main vibrational groups of the films were preserved, but with modifications in their molecular structures. It was observed by X –ray photoelectron spectroscopy chemical composition modifications in oxygen – carbon and oxygen – hydrogen bond while the deposition power changed from 10 to 50 W. The deposition rate of the samples decreased from 0.10 to 0.08 nm / minute while the RF power increases from 10 to 50 W. The samples optical properties as refractive index n, absorption coefficient, optical gap Eg were investigated by UV – Visible spectroscopy. From these analysis were possible to obtain values of n from 1.54 to 1.50 and Eg between 4.75 and 4.85 eV. Contact angle and surface energy measurements were used to investigate the wettability of composite Polymer films, for all depositions conditions the films presented hydrophilic character. EDS was used investigate components of the samples. Moreover, the film showed electrical conductivity values greater than 10-8(Ωcm)-1 and dielectric constant between 2.2 and 2.7.

Artificial lipid bilayers formed on solid surface supports are widespread model systems to study physical, chemical, as well as biological aspects of cell membranes and fundamental interfacial interactions. The approach to use a thin polymer film representing a cushion for lipid bilayers prevents incorporated membrane proteins from pinning to the support and mimics the native environment of a lipid bilayer in certain aspects of the extracellular matrix and intracellular structures. A key component for cell anchorage to extracellular fibronectin is the transmembrane adhesion receptor alpha(5)beta(1) integrin. Its transport dynamics and clustering behavior plays a major role in the assembly of focal adhesions, which mediate mechanical forces and biochemical signals of cells with their surrounding. The system investigated herein is envisioned to use extrinsically controlled stimuli-responsive polymer cushions to tune the frictional drag between polymer cushion and mobile membranes with incorporated integrins to actively regulate lipid membrane characteristics. To attain this goal, a temperature- and pH-responsive polymer based on poly(N-isopropylacrylamide) copolymers containing varying amounts of carboxyl-group-terminated comonomers at different aliphatic spacer lengths (PNIPAAm-co-carboxyAAM) was surface-grafted to a poly(glycidyl methacrylate) anchorage layer. The swelling transitions were characterized using atomic force microscopy, ellipsometry and quartz crystal microbalance with dissipation monitoring (QCM-D) and found to be tunable over a wide range of temperature and pH. In agreement with the behavior of the polymers in solution, longer alkyl spacers decreased the phase transition temperature T(P) and higher contents of carboxylic acid terminated comonomers increased T(P) at alkaline conditions and decreased T(P) at acidic conditions. Remarkably, the point where the degree of carboxyl group deprotonation balances the T(P)-lowering effect of the alkyl spacer was distinctive for each alkyl spacer length. These findings illustrate how the local and global balance of hydrophilic and hydrophobic interactions along the copolymer chain allows to adjust the swelling transition to temperatures below, comparable, or above those observed for PNIPAAm homopolymers. Additionally, it could be shown that surface-grafting leads to a decrease in T(P) for PNIPAAm homopolymers (7°C) and copolymers (5°C - 10°C). The main reason is the increase in local polymer concentration of the swollen film constrained by dense surface anchorage in comparison to the behavior of dilute free chains in solution. In accordance with the Flory-Huggins theory, T(P) decreases with increasing concentration up to the critical concentration. Biological functionalization of the PNIPAAm-co-carboxyAAm thin films was demonstrated for the cell adhesion ligand peptide cRGD via carbodiimide chemistry to mimic extracellular binding sites for the cell adhesion receptors integrin. The outcome of QCM-D measurements of cRGD-functionalized surfaces showed a maintained stimuli-responsiveness with slight reduction in T(P). A drying/rehydration procedure of a 9:1 lipid mixture of the cationic lipid dioleoyl-trimethylammoniumpropane (DOTAP) and the zwitterionic dioleoyl-phosphatidylcholine (DOPC) was utilized to form lipid bilayer membranes on PNIPAAm-co-carboxyAAM cushions. Fluorescence recovery after photobleaching (FRAP) revealed that lipid mobility was distinctively higher (6.3 - 9.6) µm2 s-1 in comparison to solid glass support ((3.0 - 5.9) µm2 s-1). In contradiction to the initial expectations, modulation of temperature and pH led to poor variations in lipid mobility that did not correlate with the PNIPAAm cushion swelling state. The results suggested a weak coupling of the lipid bilayer with PNIPAAm polymer cushions that can be slightly tuned by electrostatic interactions. The transmembrane adhesion receptor alpha(5)beta(1) integrin was reconstituted into liposomes consisting of DOPC/sphingomyelin/cholesterol 2:2:1 for the formation of polymer cushioned bilayers. PNIPAAm- co-carboxyAAM and maleic acid (MA) copolymers were used as cushions, both with the option for cRGD functionalization. On the MA copolymer cushions, fusion of proteoliposomes resulted in supported bilayers with mobile lipids as confirmed by FRAP. However, incorporated integrins were immobile. In an attempt to explain this observation, the medium-sized cytoplasmic integrin domain was accounted to hamper the movement by steric interactions with the underlying polymer chains in conjunction with electrostatic interactions of the cationic cytoplasmic domain with the oppositely charged MA copolymer. On the PNIPAAm-co-carboxyAAM cushion only a drying/rehydration procedure lead to bilayer formation. However, again the integrins were immobile, presumably due to the harsh treatment during preparation. Nevertheless, the results of the investigated set of PNIPAAm copolymer films suggest their application as temperature- and pH-responsive switchable layers to control interfacial phenomena in bio-systems at different physiological conditions. The PNIPAAm-co-carboxyAAm cushioned bilayer system represents a promising step towards extrinsically controlled membrane – substrate interactions.