Academic literature on the topic 'Stöber silica'

Magnetic silica nanocomposites (magnetic nanoparticles core coated by silica shell) have the wide promising applications in the biomedical field and usually been prepared based on the famous Stöber process. However, the flocculation of Fe3O4 nanoparticles easily occurs during the silica coating, which limits the amount of magnetic silica particles produced in the Stöber process. In this paper, PMMA/Fe3O4 nanoparticles were used in the Stöber process instead of the “nude” Fe3O4 nanoparticles. And coating Fe3O4 with PMMA polymer beforehand can prevent magnetic nanoparticles from the aggregation that usually comes from the increasing of ionic strength during the hydrolyzation of tetraethoxysilane (TEOS) by the steric hindrance. The results show that the critical concentration of magnetic nanoparticles can increase from 12 mg/L for “nude” Fe3O4 nanoparticles to 3 g/L for PMMA/Fe3O4 nanoparticles during the Stöber process. And before the deposition of silica shell, the surface of PMMA/Fe3O4 nanoparticles had to be further modified by hydrolyzing them in CH3OH/NH3˙H2O mixture solution, which provides the carboxyl groups on their surface to react further with the silanol groups of silicic acid.

ABSTRACTWe demonstrate an alternative route to synthesize functionalized silica nanoparticles through incorporation of alcohol compounds in the Stöber process. The Stöber process has been widely utilized for the synthesis of silica nanoparticles due to its simplicity and reliability. Silane based compounds have been incorporated in this process in order to tailor surface properties of the silica nanoparticles. These compounds do, however, have limitations in their utility due to side reactions with water and intermolecular polymerization. In this article, we report the incorporation of alcohol based reagents in the Stöber process as an alternative means of synthesis and functionalization of silica nanoparticles. In particular, choline chloride was chosen as an exemplary alcohol to be incorporated in the process for tuning overall surface charge of the silica nanoparticles. These silica nanoparticles with incorporated choline chloride were characterized by atomic force microscopy (AFM), zeta potential measurements, and X-ray photoelectron spectroscopy (XPS) in comparison with silica nanoparticles synthesized from the traditional Stöber process. While the size and shape of the nanoparticles exhibited little difference between the two synthetic routes, the zeta potential of the choline chloride incorporated nanoparticle was ∼10 mV higher than that of the traditional silica nanoparticles. Composition of the choline chloride containing silica nanoparticles was verified by XPS with the observation of strong N1s and C1s signals. The methods introduced in this article could be expanded to incorporate a range of alcohol containing compounds including choline chloride for the synthesis of silica nanoparticles with a tuned surface chemistry.

Polystyrene (PS) chains with molecular weights comprised between 8000 and 64000g⋅mol-1and narrow polydispersities were grown from the surface of silica nanoparticles (Aerosil A200 fumed silica and Stöber silica, resp.) through nitroxide-mediated polymerization (NMP). Alkoxyamine initiators based on N-tert-butyl-1-diethylphosphono-2,2-dimethylpropyl nitroxide (DEPN) and carrying a terminal functional group have been synthesized in situ and grafted to the silica surface. The resulting grafted alkoxyamines have been employed to initiate the growth of polystyrene chains from the inorganic surface. The maximum grafting density of the surface-tethered PS chains was estimated and seemed to be limited by initiator confinement at the interface. Then, the PS-grafted Stöber silica nanoparticles were entrapped inside latex particles via miniemulsion polymerization. Transmission electron microscopy indicated the successful formation of silica-polystyrene core-shell particles.

Microporous Stöber silica was synthesized by controlling the post-drying conditions. Using the silica as support, a highly dispersed Ni catalyst was successfully prepared by a simple impregnation method.

The “pre-Ouzo” structure directed synthesis of mesoporous silica nanoparticles (MSNs) in the absence of surfactant templates probably also explains the origin of highly monodisperse size distribution of classical Stöber silica NPs.

Role of silane-treated stöber silica as reinforcing filler for nitrile rubber (NBR) has been studied. Stöber silica is synthesized by sol–gel method, and the surface of silica is modified with the treatment of silane-coupling agent viz. γ-mercaptopropyltrimethoxysilane (γ-MPS) in varying proportions. Average particle size of stöber silica of spherical shape in the range of 200 to 400 nm is evident from scanning electron microscopy (SEM). Surface modification of silica particle with silane-coupling agents decreases surface energy and reduces agglomeration of silica particles in rubber matrix. Stress–strain study and dynamic mechanical analysis of silica-filled composites are compared with the unfilled ones. Analysis of cross-linking density, mechanical properties, and storage moduli indicates a strong rubber–filler interaction in the silane-treated, silica-filled NBR composites. Silane treatment is found to be effective in uniform dispersion of silica in rubber matrix and in improving the mechanical properties of rubber composite. Different functionalities of organosilane at its both end improve the compatibility of silica with rubber matrix and offer better rubber–filler interaction.

Orientador: Ivo Milton Raimundo Júnior
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química
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Resumo: Neste trabalho foram desenvolvidos nanossensores fluorescentes reutilizáveis para determinação de íons Cu(II) através do encapsulamento da rodamina B em nanopartículas de sílica (NPSRB ¿ 5), sintetizadas com base no método de Stöber. Objetivando identificar, compreender e, consequentemente, controlar todos os parâmetros envolvidos na síntese, foram realizados estudos uni e multivariado. No estudo univariado foram avaliados os efeitos da temperatura, velocidade de agitação, concentração do catalisador (hidróxido de amônio), concentração de água, razão molar [água] / [TEOS] e [etanol] / [TEOS]. No estudo multivariado foram avaliados os efeitos da água, TEOS, etanol e hidróxido de amônio. Os resultados do estudo univariado mostraram que todos os parâmetros estudados apresentaram influência no tamanho e morfologia das nanopartículas. No estudo multivariado foi possível identificar que as variáveis envolvidas na síntese apresentam tais efeitos somente em condições específicas. Após a identificação e, consequentemente, um maior controle dos parâmetros envolvidos na síntese de nanopartículas, iniciou-se o desenvolvimento dos nanossensores fluorescentes reutilizáveis. Neste trabalho dois nanossensores foram desenvolvidos com concentração do catalisador (NH3) de 0,18 mol L-1 para o nanossensor 1, e 0,70 mol L-1 para o nanossensor 2. O nanossensor 2, produzido em uma síntese de 2 h, não apresentou resposta a íons Cu(II) (supressão de fluorescência), isso porque as nanopartículas não possuíam porosidade, o que impediu o acesso dos íons Cu(II) à rodamina. O nanossensor 1, desenvolvido em uma síntese de 7 h, apresentou resposta a íons Cu(II). O reagente luminescente foi adicionado em diferentes estágios da síntese (2, 3, 4 e 5 h), onde o nanossensor com a adição da rodamina B em 5 h de síntese apresentou os melhores resultados. O nanossensor apresentou faixa linear entre 2,0 ¿ 12,0 µmol L-1, limite de detecção de 0,40 µmol L-1, limite de quantificação de 1,3 µmol L-1, tempo de resposta de 50 s e seletivo a íons Cu(II) podendo ser reutilizado 3 vezes. O nanossensor foi aplicado na determinação de íons Cu(II) em cachaça, produzindo resultados que não diferiram significativamente ao nível de confiança de 95 % dos resultados obtidos por espectrometria de absorção atômica
Abstract: In this work, a reusable fluorescent nanosensor for determination of Cu(II) ions was developed by encapsulating rhodamine B in silica nanoparticles synthesized based on Stöber method. In preliminary studies, it was possible to identify a relationship between the performance of nanossensor and the properties of the silica nanoparticles. In order to identify, understand and thus control all the parameters involved in the synthesis, univariate and multivariate studies were performed. In the univariate study, it was evaluated the effect of temperature, stirring speed, catalyst concentration (ammonium hydroxide), water concentration, and [water] / [TEOS] and [ethanol] / [TEOS] molar ratios. In the multivariate study, it was evaluated the effect of water, TEOS, ethanol and ammonium hydroxide. Results obtained in the univariate study showed that all parameters affect the size and the morphology of the nanoparticles. In the multivariate study, it was found that the variables involved in the synthesis have such effects only under specific conditions. After identification and, consequently, better control of the parameters involved in the synthesis of nanoparticles, the development of fluorescent nanosensors was carried out. Two nanosensors were developed, synthesized with catalyst concentration (NH3) of 0.18 mol L-1 for the nanosensor 1, and 0.70 mol L-1 for the nanosensor 2. The nanosensor 2, developed in a synthesis of 2 h, did not present response to Cu(II) ions (fluorescence quenching), because nanoparticles did not present porosity, which prevented the access of Cu(II) ion to rhodamine. The nanosensor 1, developed in a synthesis of 7 h, showed response to Cu(II) ions. The luminescent reagent was added at different stages of the synthesis (2, 3, 4 and 5 hours), and the nanosensor obtained with addition of rhodamine B after 5 h of synthesis showed the best results. The nanosensor showed linear range from 2.0 to 12.0 µmol L-1, detection limit of 0.40 µmol L-1, quantification limit of 1.3 µmol L-1, response time of 50 s and selectivity to Cu(II) ions which can be reused 3 times. The nanosensor was applied to the determination of Cu(II) in sugar cane spirit and the results obtained did not show significant differences from those obtained by atomic absorption spectrometry at a confidence level of 95 %
Mestrado
Quimica Analitica
Mestre em Química

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In this work, we synthesized core/shell magnetic composite type consisting of maghemite nanoparticles covered with a coating layer of amino-functionalized silica. The experimental procedure was based on four steps: i) synthesis of magnetite nanoparticles and subsequent oxidation to maghemite, ii) preparation of aqueous colloidal dispersions (ferrofluids), from maghemite nanoparticles with modal diameter of 8.4 nm or 7.2 nm functionalized with citrate ion, iii) preparation of silica magnetic nanospheres (NMS) by the modified Stöber method using different amounts of ferrofluids and tetraethoxysilane (TEOS), and iv) functionalization of silica nanospheres with amino groups using aminopropyltrimethoxysilane (APTS). Sample characteristics of NMS were determined from the iron content measurements, from high-resolution transmission electron microscopy (HRTEM) and from vibrating sample magnetometry (VSM) and they were evaluated on the basis of the synthetic parameters employed, these being the content of magnetic material (nFe/nTEOS = 0.05, nFe/nTEOS = 0.01 e nFe/nTEOS = 0.002) and the type of used ferrofluid; a freshly prepared ferrofluid or an aged ferrofluid. The study of ferrofluids by static magnetic birefringence (SMB) showed that both had aggregates of magnetic nanoparticles, although higher for the aged ferrofluid. Samples of NMS were heterogeneous, showing fractions with different amounts of magnetic material embedded. Samples obtained from the aged ferrofluid, especially those prepared from smaller ferrofluid volumes (nFe/nTEOS = 0.01 e nFe/nTEOS = 0.002), showed the presence of magnetic silica particles and "empty" silica particles, that is, free from magnetic nanoparticles. This fact was attributed to xxvii the greater degree of maghemite nanoparticles aggregation in aged ferrofluid and therefore to fewer available magnetic cores in the reaction environment for the deposition of silica by heterogeneous nucleation mechanism. The NMS particles sizes ranged from 140 to 700 nm, and most particles were larger than the expected average size (150 nm), according to the molar ratio of reagents used in the Stöber synthesis. The presence of silica particles with spherical morphology was also observed, as well as coalesced silica particles. These morphological characteristics were attributed to the size and to the arrangement of magnetic nanoparticles in the cores (compact or dispersed), which were present in the reaction mixtures. After coating with silica, nanoparticles of maghemite remained superparamagnetic at room temperature, although there was a reduction in the value of saturation magnetization. The saturation magnetization value of maghemite within the ferrofluids was 62.1 or 68.7 emug-1, whereas saturation magnetization values of maghemite within the NMS ranged between 9.5 and 37 emug-1. Nanostructured magnetic materials obtained in this work, especially the NMS prepared from the higher ratio Fe/TEOS, have greater potential of use as magnetic beads due to higher values of saturation magnetization and the possibility of being quickly attracted by the magnetic field of a permanent magnet.
Neste trabalho, foram sintetizados compósitos magnéticos do tipo caroço/casca, constituídos por nanopartículas de maghemita recobertas com uma cobertura de sílica aminofuncionalizada. O procedimento experimental baseou-se em quatro etapas: i) síntese de nanopartículas de magnetita e, posterior oxidação para maghemita, ii) preparação de dispersões coloidais aquosas (ferrofluidos), a partir de nanopartículas de maghemita com diâmetro modal de 8,4 nm ou 7,2 nm e funcionalizadas com íons citrato, iii) preparação de nanoesferas magnéticas de sílica (NMS) pelo método de Stöber modificado, utilizando diferentes volumes dos ferrofluidos e tetraetoxissilano (TEOS), e iv) funcionalização das nanoesferas de sílica com grupos amino empregando-se aminopropiltrimetoxissilano (APTS). As características das amostras de NMS foram determinadas a partir de medidas do teor de ferro, microscopia eletrônica de transmissão de alta resolução (HRTEM) e magnetometria de amostra vibrante (VSM), e foram avaliadas em função dos parâmetros variados nas sínteses, sendo esses o teor de material magnético (nFe/nTEOS = 0,05, nFe/nTEOS = 0,01 e nFe/nTEOS = 0,002) e o tipo de ferrofluido empregado; um ferrofluido recém-preparado ou um ferrofluido envelhecido. O estudo dos ferrofluidos por birrefringência magnética estática (SMB) mostrou que ambos apresentavam agregados de nanopartículas magnéticas, embora maiores para o ferrofluido envelhecido. As amostras de NMS foram heterogêneas, apresentando frações com quantidades distintas de material magnético incorporado. Nas amostras obtidas a partir do ferrofluido envelhecido, principalmente naquelas preparadas a partir de volumes menores de ferrofluido (nFe/nTEOS = 0,01 e nFe/nTEOS = 0,002), foram observadas tanto a presença de partículas de sílica xxv magnética, quanto partículas de sílica “vazias”, ou seja, isentas de nanopartículas magnéticas. Esse fato foi atribuído ao maior grau de agregação das nanopartículas de maghemita no ferrofluido envelhecido e, portanto, ao menor número de núcleos magnéticos disponíveis no meio reacional para a deposição de sílica pelo mecanismo de nucleação heterogênea. O tamanho das partículas de sílica magnética variou entre 140 e 700 nm, sendo a maioria das partículas maiores do que o tamanho médio previsto (150 nm), conforme a proporção molar de reagentes utilizada nas sínteses de Stöber. Também foi observada a presença de partículas de sílica com morfologia esférica, bem como de partículas de sílica coalescidas. Essas características morfológicas foram atribuídas ao tamanho e ao modo de organização das nanopartículas magnéticas nos núcleos (arranjo compacto ou disperso), os quais estavam presentes nas misturas reacionais. Após o recobrimento com sílica, as nanopartículas de maghemita permaneceram superparamagnéticas na temperatura ambiente, embora tenha ocorrido redução no valor da magnetização de saturação. O valor da magnetização de saturação estimado para a maghemita nos ferrofluidos foi de 62,1 ou 68,7 emug-1, de acordo com o diâmetro modal, enquanto que para as amostras de NMS, os valores variaram entre 9,5 e 37 emug-1. Os materiais magnéticos nanoestruturados obtidos nesse trabalho, principalmente as NMS preparadas a partir da maior razão Fe/TEOS, apresentam potencialidades de uso como grãos magnéticos, devido aos maiores valores de magnetização de saturação e à possibilidade de serem atraídas rapidamente pelo campo magnético de um imã permanente.

Dans ce travail, les nanoparticles d'or supportées ont été étudiées en raison de leur fort potentiel dans les domaines de la catalyse. Des sphères de silice obtenues par la voie Stöber ont été synthétisées et utilisées comme supports des nanoparticules d'or. Les précurseurs d'or sont des solutions colloïdales possédant des nanoparticules d'or homogènes et de petite taille (environ 3 nm). Les matériaux préparés avec ou sans addition d'un nouvel élément ont été utilisés dans les réactions de l'oxydation du CO et une réaction inédite pour l'or: l'oxydation sélective de l'H2S.Les résultats indiquent que l'utilisation de colloïdes d'or comme précurseurs permet de contrôler la taille et la dispersion avant le dépôt et ceci est facilité par les propriétés optiques des nanoparticules de ce métal. Pour les propriétés catalytiques, outre la dispersion, on confirme très clairement par cette méthode de synthèse que l'interaction Au/Support joue un rôle majeur. L'addition d'un second métal augmente significativement l'activité des matériaux à base d'or. Les particules d'or et de Cu se rassemblent sous les conditions réactionnelles testées. Dans le cas de l'oxydation du CO, de petites quantités d'espèce d'or partiellement oxydée sont générées et forment une glue avec les espèces Cu2+ également formées au cours de la réaction et ceci permet de fixer les nanoparticules sur le support. Dans le cas de l'oxydation sélective de H2S, il a été montré que le système est résistant au soufre, y compris sur une longue durée de test. Les silices Stöber se sont avérées comme des supports catalytiques très intéressants car non poreux et formés de particules de petites tailles, ils sont aptes à exposer les phases actives de l'or aux réactifs, diminuant la pression de surface et facilitant le transfert thermique. Il a également été prouvé que ce matériau peut être mis en compétition avec les matériaux mésoporeux, ces derniers étant jugés indispensables pour obtenir de hautes activités en catalyse hétérogènes jusque là.

L’étude de la précipitation de la silice amorphe à partir de TétraEthylOrtoSilicate (TEOS) et d’eau, selon le procédé Stöber, a permis de quantifier la cinétique de réaction par spectroscopie Infra Rouge à Transformée de Fourrier. Nous avons montré que la croissance des particules se fait par agrégation des nuclei, qui sont formés tout au long de la réaction. La transposition de ce procédé en microémulsion eau-dans-huile a permis de synthétiser des nanoparticules de silice de tailles contrôlées. L’hydrolyse du TEOS est ici dix fois plus faible qu’en phase homogène. Lors de l’ajout du TEOS à la microémulsion, on observe une coalescence des gouttelettes accompagnée d’échanges inter-micellaires. Ce phénomène a pu être décrit par un noyau d’agrégation qui dépend des concentrations en tensioactif et en TEOS non hydrolysé. L’étude de ce procédé en macroémulsion a montré l’effet déstabilisateur de l’éthanol et la nécessité de stabiliser l’émulsion pour synthétiser des particules sphériques
The study of the precipitation of amorphous silica starting from Tetraethoxysilane (TEOS) and water according to the Stöber process, made it possible to quantify the kinetics of the reaction by Fourier-Transform Infrared spectroscopy. We demonstrated that the particles grow by aggregation of the nuclei, which are formed throughout the reaction.The transposition of this process in water-in-oil microemulsion made it possible to synthesize silica nanoparticules with controlled sizes. The hydrolysis of the TEOS is here ten times weaker than in homogeneous phase. When we add the TEOS to the microemulsion, we observe a coalescence of the droplets accompanied by inter-micellar exchanges. This coalescence is well described by a core of aggregation which depends on the concentrations of the surfactant and the non-hydrolysed TEOS. The study of this process in macroemulsions showed the destabilizing effect of ethanol and the need for stabilizing the emulsion to synthesize spherical particles

L’objectif était de développer et d’utiliser des nanoparticules hybrides de type«coeur-écorce» composées d’un coeur de silice dense entouré par des chaînes polymères fonctionnalisées par des ligands d’ATRP comme support catalytique pour la polymérisation du MMA par ATRP. Deux stratégies de synthèse de nanoparticules hybrides ont été élaborées. La première a consisté à immobiliser sur un support de silice, d’une manière covalente, des chaînes fonctionnelles synthétisées par NMP comportant des ligands capables de complexer le bromure de cuivre. Des nanoparticules de SiO2@polymère fonctionnel ayant de faibles densités de greffage en polymère ont été ciblées afin d’éviter leur recouvrement sur la surface. Cependant, les polymérisations n’étaient pas contrôlées probablement à cause d’un manque d’accessibilité de l’amorceur et des radicaux propageants aux complexes decuivre. Afin de rendre les catalyseurs supportés plus accessibles en solution, nous avons élaboré une seconde stratégie basée sur un système catalytique hybride réversible. Il consiste à immobiliser des chaînes α-fonctionnalisées par un motif donneur-accepteur de proton(DAD) via des liaisons hydrogène sur des particules de silice modifiées par un motif complémentaire (ADA). Des PMMA de masses molaires contrôlées ont été synthétisés avec des dispersités plus faibles que celles obtenues en ATRP homogène (en présence des chaînes libres). Après séparation du catalyseur du milieu réactionnel par centrifugation, nous avons montré qu’avec un excès du motif ADA, 96% du cuivre initialement introduit ont été récupérés
The aim of this project is to develop hybrid nanoparticles bearing well definedpolymer arms as supported catalyst for the atom transfer radical polymerization of methylmethacrylate. This new generation of “semi heterogeneous" catalysts was prepared by twostrategies. The first consisted of immobilizing the polymer arms bearing the ligands enablingcoordination of copper bromide onto silica particles by covalent bonds. Hybrid nanoparticleswith low polymer grafting density were targeted to prevent the overlapping of chains on thesurface. Unfortunately, the polymerizations were not controlled probably due to a lack ofaccessibility of the initiator and propagating radicals to the copper complexes. To improve theaccessibility, a reversibly supported catalyst was developed via self-assembly using hydrogenbonding between chains α-functionalized by a proton donor-acceptor unit (DAD) and acomplementary unit (ADA) anchored on silica particles. These new hybrid materials wereefficient in the controlled radical polymerization of MMA, yielding polymers with controlledmolecular weights and dispersities narrower than those obtained for homogeneous ATRP.Moreover, after catalyst separation from the reaction medium by centrifugation, more than96% of the originally used copper was recovered

Ziel der Diplomarbeit ist es, eine Dispersion aus Monomer und Silika-Partikeln auf ein festes Substrat aufzutragen, die so erhaltenen Versuchsträger mit dem Monomer/Partikel-Film (Modell Monomer/Partikel/festes Substrat) anschließend mit dem Rasterkraftmikroskop abzubilden und anschließend hinsichtlich der Oberflächenkrümmung und dem Kontaktwinkel zu untersuchen. Durch die Kontaktwinkelmessung am Dreiphasenpunkt soll eine erste Charakterisierung der kapillaren Oberfläche erfolgen, die jedoch nur ein Teilschritt bis zur vollständigen Optimierung von durch partikel-assistierte Benetzung hergestellte poröse Membranen ist.

La thermothérapie consiste à soigner un tissu cancéreux par la chaleur, par destruction directe de la tumeur (thermoablation) ou amélioration de traitements radiothérapeutiques ou chimiothérapeutiques (hyperthermie). Une des voies les plus prometteuses de thermothérapie consiste à utiliser l'échauffement de nanoparticules magnétiques La0. 75Sr0. 25MnO3 ont été synthétisées par voie Pechini. Ces nanoparticules présentent un échauffement magnétique autorégulé, c'est-à-dire que lorsque la température du milieu s'approche de leur température de Curie, les nanoparticules perdent leur capacité d'échauffement, empêchant tout risque de chauffage excessif. L'influence des conditions de synthèse de ces particules, ainsi que de la fréquence et de l'amplitude du champ magnétique sur l'échauffement de ces particules a été étudiée. L'appareil d'induction multifréquence, construit au cours de cette thèse, devrait à court terme permettre de mieux comprendre les phénomènes d'échauffement magnétique de ces particules. Les nanoparticules La0. 75Sr0. 25MnO3 ont été encapsulées dans de la silice par voie Stöber puis aminées par ajout d'aminosilanes : cette modification de surface ouvre de nombreuses possibilités (furtivité des nanoparticules vis-àvis dusysthème immunitaire par greffage de polyoxyéthylène, ciblage de cellules-cibles par greffage de ligands appropriés, etc. ). Un polymère thermosensible à base de poloxamers, capable de piéger des molécules-tests à "basse" température et de les libérer sous l'effet de l'échauffement magnétique, a été synthétisé et les premiers tests de libération de colorant sous l'effet de l'échauffement magnétique de nanoparticules La0. 75Sr0. 25MnO3 piégées dans ce gel se sont révélés très prometteurs.

Mesoporous silica nanoparticles provide a versatile drug-delivery platform due to their exceptional properties, such as, high payload uptake, tunable pore width and particle size and protection over the guest molecule. The external surface can be functionalize with bioactive molecules and stimuli responsive polymers, improving the biocompatibility and drug bioavailability, increasing the local dose delivered and decreasing the side effects. The objective of this work was to synthesize fluorescent hybrid MSNs, coated with a co-polymeric shell containing pH-responsive and carbohydrate blocks obtained through RAFT polymerization. Such combination opens the possibility of diagnosis, through carbohydrates recognition ability towards cancer cells, and therapy by a pH mediated controlled release. The fluorescent silica nanoparticles were prepared by the Stöber method, incorporating a high quantum yield perylenediimide (PDI) in the silica structure. The nanoparticles were characterized by transmission electronic microscopy, with diameters of 30 nm and 65 nm with low size dispersity. The homo and co-polymers were synthesized by RAFT polymerization and characterized by UV-Vis and size exclusion chromatography (SEC), with a polydispersity below 1.2. The external surface of the MSNs was functionalized to allow the immobilization of the smart polymer. Surface modifications were assessed and quantified using 1H-NMR, UV-Vis and ζ-Potential. Polymer immobilization on the MSNs external surface were performed using four different methods: “transfer to”, “graft to”, “graft from” and a hybrid method. The particles modified with the homo carbohydrate polymer were obtained with polymer weight percentage between 0.5% and 4.3%. The immobilization of the final pH-responsive/carbohydrate co-polymer was achieved with a 2% polymer weight via “graft to” method. The immobilization by the hybrid method was also achieved, with promising results, indicating that our strategy is correct.

Ziel der Diplomarbeit ist es, eine Dispersion aus Monomer und Silika-Partikeln auf ein festes Substrat aufzutragen, die so erhaltenen Versuchsträger mit dem Monomer/Partikel-Film (Modell Monomer/Partikel/festes Substrat) anschließend mit dem Rasterkraftmikroskop abzubilden und anschließend hinsichtlich der Oberflächenkrümmung und dem Kontaktwinkel zu untersuchen. Durch die Kontaktwinkelmessung am Dreiphasenpunkt soll eine erste Charakterisierung der kapillaren Oberfläche erfolgen, die jedoch nur ein Teilschritt bis zur vollständigen Optimierung von durch partikel-assistierte Benetzung hergestellte poröse Membranen ist.