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Williams, Timothy Philip. "Computer simulation of randomly cross-linked polymer networks." Thesis, University of Bristol, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271736.
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Ferrier, David Christopher. "Nucleic acid detection using oligonucleotide cross-linked polymer composites." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/28944.
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There has been much interest in recent years about the potential of microRNA as a new source of biomarkers for the diagnosis of disease. The delivery of new diagnostic tools based on this potential has been limited by shortcomings in current microRNA detection techniques. This thesis explores the development of a new method of microRNA detection through the incorporation of conductive particles into oligonucleotide-functionalised polymers to form oligonucleotide cross-linked polymer composites. Such composites could provide a simple, rapid, and low-cost means of microRNA detection that could be easily multiplexed, providing a valuable tool for point-of-care medical diagnostics. This work presents oligonucleotide-functionalised carbon/polyacrylamide composites which demonstrate a selective swelling response in the presence of analyte oligonucleotide sequences and for which the electrical conductivity decreases with swelling. The composites were synthesised via UV-initiated free-radical polymerisation of carbon/- monomer mixtures upon custom electrode devices, consisting of interdigitated platinum electrodes fabricated upon a silicon substrate. The optimal cross-linker density and carbon loading concentration were determined as well as the best means of dispersing the carbon particles within the polymer. Various types of carbon particles, with differing sizes and aspect ratios, were compared and their performances as conductive additives for polymer swelling transduction evaluated. The swelling behaviour of these composites was evaluated by analysing images of composite microdroplets as they swell. The electrical characteristics of the composites were determined by measuring either the two-terminal resistance or the complex impedance of composite microdroplets on the electrode devices. Alternating and direct current measurement techniques were compared to determine the best approach for the transduction of composite swelling. The volumetric and electrical responses of oligonucleotide-functionalised carbon/polyacrylamide composites were analysed in solutions of analyte oligonucleotide and non-complementary controls. It has been demonstrated that, using carbon nanopowder composites and a direct current two-terminal resistance measurement, it is possible to differentiate between analyte and control solutions to concentrations as low as 10 nM, with single-base precision, in less than three minutes. However, the inability to detect at concentrations below this value, difficulties in differentiating between different analyte concentrations and thermal instability mean that, in their current form, oligonucleotide cross-linked polymer composites are unsuitable for the detection of circulating microRNA at clinically relevant concentrations. Potential avenues of work to address these challenges are discussed. Also presented are collaborative results for oligonucleotide-responsive polymers functionalised with morpholino nucleic acid analogues, in what is believed to be the first example of such a material. These morpholino-functionalised polymers offer significant advantages, in terms of stability and sensitivity, over their nucleic acid equivalents for bio-responsive polymer applications.
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Scavuzzo, Joseph J. "Elastomers Physically Cross-Linked By Oligo(ß-Alanine)." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1412937878.
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Breed, Peter G. "Organic chemistry on highly functionalised supports." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312151.
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O'Neill, Jason Michael. "Multidimensional Mass Spectrometry Studies on Amphiphilic Polymer Blends and Cross-Linked Networks." University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1624375174939496.
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D, Aguiar Donna-Leigh. "Surface modified cross-linked poly(vinyl alcohol)/poly(vinyl pivalate) suspension particles." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/5475.
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Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2010.ENGLISH ABSTRACT: In papermaking, fillers and additives are used to enhance paper properties. In this study spherical modified poly(vinyl alcohol) (PVA) particles were prepared for use as fillers. In order to determine the mechanism of adhesion of additives to cellulose (paper) fibres, these particles were modified to have surface functionality, with cationic and anionic surface charges, similar to charged polyelectrolyte additives. Typically, retention aids used to improve the fibre–fibre and fibre–filler bonding are able to conform to the surface of the fibres and fillers. Oppositely charged components show strong affinity for each other, e.g. cationic polyelectrolyte groups adhere to anionic surface charges on the fibres. The spherical PVA particles were prepared by the saponification of spherical poly(vinyl pivalate) (PVPi) precursor particles. These PVPi particles, prepared via suspension polymerisation, were cross-linked with a divinyl ether comonomer. The vinyl pivalate (VPi) suspension polymerisation was successfully carried out and afforded relatively uniformly distributed PVPi particles, with diameters of 0.5–10 mm. The cross-linked PVPi particles were then saponified in tetrahydrofuran (THF) as swelling solvent, to afford PVA with various degrees of saponification (DS). The spherical shape was lost and fibrous material was obtained when uncross-linked PVPi particles were saponified. Cross-linking the spherical PVPi particles (PVA precursor) proved innovative, and essential in maintaining the spherical form during saponification to PVA/PVPi. By varying the saponification time periods, various DS were obtained, as characterised by solid state NMR spectroscopy. Surface modification of the PVA/PVPi particles was carried out with cationic and anionic groups via the Williamson ether synthesis. Ionic modification of these rigid spherical PVA/PVPi particles was carried out in order to study their adherence to cellulose fibres, compared to the adherence of similarly modified starches with cellulose fibres. Fluorescent labelling of the different modified particles was carried out using two complimentary coloured fluorescent markers. Fluorescence imaging and scanning electron microscopy (SEM) enabled the observation of particle– fibre and particle–particle interaction. Results indicated that the negative groups are sparse on the cellulose fibres, and therefore particles with low functionality but which are able change shape and conform and adhere to the surface of the cellulose fibres are required for effective adhesion. These modified spherical PVA/PVPi particles are unique as they mirror the chemistry of functionalised starch and cellulose particles, yet maintain their shape and have a fixed size, measurable by SEM and transmission electron microscopy (TEM). Field-flow fractionation was also used to characterise and measure these relatively large cross-linked and fixed diameter particles.
AFRIKAANSE OPSOMMING: In papierproduksie word vulstowwe en bymiddels gebruik om die eienskappe van papier te verbeter. In hierdie studie is sferiese poli(vinielalkohol) (PVA) partikels berei vir gebruik as vulstowwe. Om ten einde die meganisme van die bymiddelklewing aan die sellulose vesels (papier) te bepaal, is die oppervlakke van hierdie partikels gewysig met kationiese of anioniese groepe, om 'n oppervlak soortgelyk aan dié van funksionele poliëlektrolietbymiddels te verskaf. Die retensiemiddels wat gebruik word om die vesel–vesel en vesel–vulstof binding te verbeter is tipies in staat om te konformeer aan die oppervlak van die vesels en vulstowwe. Teenoorgesteldgelaaide komponente toon 'n sterk affiniteit vir mekaar, bv. kationiese poliëlektrolietgroepe is vasklewend aan die anioniesgelaaide oppervlakke van die vesel. Die sferiese PVA partikels is berei deur die verseping van sferiese poli(vinielpivalaat) (PVPi) partikels. Hierdie voorloper PVPi partikels, berei deur suspensiepolimerisasie, is gekruisbind met 'n divinieleter ko-monomeer. Die vinielpivalaat (VPi) suspensiepolimerisasie is suksesvol uitgevoer en relatief eenvormig verspreide sferiese PVPi partikels is berei, met deursnitte tussen 0.5–10 mm. Die gekruisbinde PVPi partikels is daarna gesaponifiseer in tetrahidrofuraan (THF) as oplosmiddel, om PVA met verskillende grade van verseping (DS) te berei. Die sferiese vorm raak verlore en veselagtige materiaal is verkry wanneer PVPi partikels met geen kruisbinding verseep is. Kruisbinding van die sferiese PVPi partikels (PVA voorloper) is voordelig en noodsaaklik om die sferiese vorm tydens die verseping tot PVA/PVPi te behou. Deur die tydsduur van verseping te verander, is verskeie grade van verseping verkry en bevestig deur vaste toestand KMR spektroskopie. Oppervlakwysiging van die PVA/PVPi partikels, om kationiese en anioniese groepe aan te heg, is uitgevoer via die Williamson etersintese. Ioniese wysiging van hierdie stram, sferiese PVA/PVPi partikels is uitgevoer om ten einde hul klewing met sellulose vesels te bestudeer en te vergelyk met die klewing van soortgelyk gewysigde stysels. Fluoressensie merking van die verskillende gewysigde partikels is uitgevoer met behulp van twee komplimentêre gekleurde fluoressensie merkers. Fluoressensie beeldvorming en SEM verskaf die waarneming van partikel–vesel en partikel–partikel interaksie. Die resultate dui daarop dat die negatiewe groepe van die sellulose vesels skaars is, en daarom is partikels met ‘n lae funksionaliteit, maar wat in staat is om van vorm te verander, aan te pas en te konformeer aan die oppervlak van die sellulose vesels, nodig vir effektiewe adhesie. Hierdie gewysigde sferiese PVA/PVPi partikels is uniek aangesien hulle die chemie van gewysigde stysel en sellulose partikels naboots, maar steeds hul vorm behou met 'n vaste grootte; meetbaar deur SEM en TEM. Veld-vloei-fraksionering is ook gebruik vir die karakterisering van hierdie relatief groot, stram, gekruisbinde partikels met bepaalde deursneë.
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Patra, Leena. "Volume-Phase Transitions in Responsive Photo-Cross-Linked Polymer Network Films." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4197.
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The overall thrust of this project is to gain an insight into a class of surface-tethered cross-linked thin films of poly(N-alkylacrylamides) that display a lower critical solution temperature (LCST).The structure of the alkyl group and the modification of the amide groups determine the LCST and resultant volume-phase transition behavior. The aim of this study involves synthesis and characterization of thin films and to correlate the volume-transition behavior to the structure of the alkyl group. For better understanding the volume-transition behavior, the polymer films are perturbed by the Hofmeister salt series to examine trends between different alkyl groups. While most of the studies have been done with bulk gels, the majority of the applications require the use of gels at surfaces and interfaces. Surface attached polymer networks provide an alternative to bulk gels showing superior response times, thus efficiency. Hence it is significant to understand the impact of confinement on the phase transition behavior of a polymer network. Anchoring a polymer network to a surface produces volume phase transition perpendicular to the substrate. The parallel swelling and collapse of the network is highly restricted due to lateral confinement, thus impacting properties such as structure, mechanical properties, dynamics and permeability of the network. Several studies have been done with poly(N-isopropylacrylamide) anchored to a substrate, which have shown significantly different behavior than unconstrained networks. Notable examples include a gradual as opposed to a sharp volume-phase transition, and significantly less swelling above and below the LCST. These studies only looked at poly(NIPAAm); therefore it
remains unknown if these results are universal and will apply to other LCST polymers. Hence, we expanded upon these studies to also investigate a library of different LCST polymers belonging to the category of N-alkylacrylamides.
I have synthesized the copolymers comprising of N-alkylacrylamides and methacryloxybenzophenone (MaBP). The benzophenone moiety in MaBP is photoreactive, allowing us to cross-link the copolymers by UV irradiation. Surface attached thin films were fabricated by spin coating the solution of copolymers and cross-linking by UV irradiation. The volume phase transitions of the coatings were studied under the influence of temperature and the salts of the Hofmeister series. Information concerning the state of responsive layers, the precise temperature at which the collapse occurs, and the changes in the molecular environment during the transition were investigated by ellipsometry and ATR-FTIR. In a longer perspective, understanding the transition behavior and the influence of salts governing this transition provides a better understanding of the interactions of biopolymers in natural systems.
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Deng, Guodong. "SYNTHESIS AND CHARACTERIZATION OF IONICALLY CROSS-LINKED NETWORKS THROUGH THE USE OF ION-PAIR COMONOMERS." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1534124831858723.
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Michon, Marie-Laure. "Heterogeneous epoxy-amine networks from the dispersion of cross-linked polymer microparticles." Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0018/document.
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Lors de cette étude, il a été étudié l'influence de l'ajout de microparticules de polymère réticulé (CPM) dans des formulations d'époxy-amine, sur la cinétique, la morphologie et les propriétés thermo-mécaniques des réseaux finaux obtenus. Tout d'abord, un protocole simple, robuste et bien contrôlé a été développé afin d’ obtenir une large gamme de taille de CPM, de Tg et de fonctionnalité amine. Ce protocole de polymérisation par précipitation, basé sur les phénomènes de séparation de phases, a également été appliqué à différentes compositions chimiques et différents monomères époxy hydrosolubles, ceci montrant les grandes possibilités de cette méthode. Une bonne interface entre les CPMs et la matrice a été recherchée en synthétisant les CPMs en excès de groupes amines. La quantification de ces groupes amines réactifs sur les CPMS était d'un grand intérêt et a donc été étudiée en profondeur. Le titrage des amines de surface a été réalisé en mettant au point un nouveau protocole qui a permis la quantification des amines primaires et secondaires sur les CPMs. Il a ensuite été mis en évidence que, bien que ces microparticules réticulées ne soient pas poreuses, des fonctions amines sont disponibles au cœur des particules et peuvent réagir avec d'autres molécules qui sont capables de diffuser dans la CPM. Il a été montré que lorsque les CPM ont été dispersées dans des mélanges d'époxy- amine, la diffusion des monomères dans le cœur de la CPM s'est produite mais différemment selon le procédé de dispersion. En effet, en utilisant le tétrahydrofurane comme solvant pour aider à la dispersion, la diffusion de la DGEBA est amplifiée et modifie les propriétés thermo-mécaniques du réseau final en modifiant le rapport stœchiométrique de la matrice. Le même phénomène a été observé mais moins amplifié lorsque les microparticules sont uniquement dispersées mécaniquement. En dispersant les CPMs dans l'amine qui est l'agent réticulant, on observe l'absorption complète de l'amine au coeur des CPMs, conduisant ainsi à la désorption de celle-ci dans une deuxième étape, permettant de créer le réseau. Ainsi, un comportement très complexe des CPM a été mis en évidence en présence des monomères et/ou solvant : le gonflement et les phénomènes de diffusion qui dépendent d'un certain nombre de paramètres tels que la température, la densité de réticulation des CPM, les paramètres de solubilité, etc. L'intensité du phénomène de diffusion conduit à une variété de comportements lorsque les CPMs sont ajoutées dans une formulation d'époxy-amine tels que: (a) une légère diminution du temps de gélification et l'augmentation de la conversion, (b) la modification de la température de transition vitreuse de la matriceThroughout this work, the influence of the addition of cross-linked polymer microparticles (CPMs) in epoxy-amine formulations on the kinetics, morphology and thermo-mechanical properties of the final networks have been investigated. First, an easy, robust and well-controlled protocol was developed to obtain a large range of CPM size, Tg and amine functionality. This protocol based on reaction induced phase separation via precipitation polymerization was also applied to different chemistries and water soluble epoxy pre-polymers showing the large possibilities of this method. The capacity of obtaining a good compatibility between the CPMs and the matrix was ensure by synthesizing the CPMs in excess of amino groups. The study of the remaining reactive amino groups on the CPMS was of great interest and therefore deeply investigated. The titration of the surface amine was performed by developing a new protocol that enabled the quantification of primary and secondary amines on CPMs. It was then highlighted that even though these cross-linked microparticles were not porous, amino groups are available into the core and can react with other molecules that are able to diffuse into the CPM core. It was shown that when CPMs were dispersed into epoxy-amine blends, the diffusion of monomers into the CPM core occurred but differently depending on the dispersion process. Indeed, using tetrahydrofuran as solvent to help for the dispersion increased the diffusion of DGEBA into the CPM core and changed the thermo-mechanical properties of the final network by modifying the stoichiometric ratio of the matrix. Same phenomenon was observed but less amplified when CPMs were mechanically dispersed in DGEBA. Regarding the dispersion of CPMs in the amine cross-linker, IPD, its complete absorption could be observed into the CPMs, leading then to the desorption of IPD to create the network. Thus, a very complex behavior of CPMs was highlighted in presence of monomers or/and solvent: swelling and diffusion phenomena that are dependent on a number of parameters such as temperature, CPM cross-link density, solubility parameters, etc. The intensity of those phenomena leads to a variety of behaviors when CPMs are added into an epoxy-amine formulation: (a) slight decrease of gel times and increase of conversion, (b) modification of glass transition temperature of the matrix
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Shmelin, George. "A new rheological polymer based on boron siloxane cross-linked by isocyanate groups." Thesis, University of Hertfordshire, 2012. http://hdl.handle.net/2299/13901.
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The research described in this thesis originated from an idea to develop new body protection for the sport of fencing. The ultimate goal is to develop body armour which would be flexible, wearable, washable, light and breathable, offer protection from injuries and cover the entire body of a sportsman. A new material which exhibits shear thickening behaviour has been specially developed for this purpose in the process of this investigation. The material was designed and synthesised as a soft polymeric system which is flexible, chemically stable and able to increase the value of its modulus of elasticity upon impact at a high strain rate, while remaining in its soft gel-like elastomeric state when low strain rate deformation is applied. The polymeric system that has been developed is based on interpenetrating polymeric networks (IPN) of immiscible polyurethane/urea-ester/ether and poly(boron)n(dimethylsiloxane)m (where on average m ≈ 16 n). In addition, as the polydimethylsilane (PDMS) based polymeric system strongly tends to phase separation, the siloxane polymeric network was chemically cross-linked to the polyurethane polymeric network through polyurethane chemical cross-link-bridges. In order to introduce polyurethane cross-links to a siloxane-based polymeric network, some of the attached methyl groups in the PDMS polymeric backbone were substituted by ε-pentanol groups. The resulting polymeric system combines properties of an alternating copolymer with IPN. The actual substitution of the methyl groups of PDMS into alternating ε-pentanol groups was performed by Grignard reaction of trifunctional chlorosilane monomers, magnesium and 1,5-dibromopentane. Chemical analytical techniques like FT-IR, 13C NMR and 1H NMR spectroscopy were used to reveal the chemical structure of the synthesised polymeric network. The mechanical and dynamical properties of the obtained polymeric system were analysed by dynamic mechanical analysis (DMA). This part of the investigation indicated that the novel polymeric system exhibited shear thickening behaviour, but only at a narrow diapason of deformations (i.e., deformations between 2 to 3 % of the length of the sample). At this limited diapason of deformation an effective increase of the modulus of elasticity from 6 MPa (at lower frequencies, i.e., up to ≤6 Hz of the applied oscillating stress) to 65 MPa (at frequencies between 12.5 to 25 Hz) was obtained. However, no increase in the modulus of elasticity was recorded at deformations below 1.5 % or above 3.5 % of length of the sample at the same frequencies (0 to 25Hz) of the applied oscillating stress.
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ten, Brummelhuis Niels. "Self-assembly of cross-linked polymer micelles into complex higher-order aggregates." Phd thesis, Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2011/5232/.
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The creation of complex polymer structures has been one of the major research topics over the last couple of decades.
This work deals with the synthesis of (block co-)polymers, the creation of complex and stimuli-responsive aggregates by self-assembly, and the cross-linking of these structures. Also the higher-order self-assembly of the aggregates is investigated.
The formation of poly-2-oxazoline based micelles in aqueous solution and their simultaneous functionalization and cross-linking using thiol-yne chemistry is e.g. presented. By introducing pH responsive thiols in the core of the micelles the influence of charged groups in the core of micelles on the entire structure can be studied. The charging of these groups leads to a swelling of the core and a decrease in the local concentration of the corona forming block (poly(2-ethyl-2-oxazoline)). This decrease in concentration yields a shift in the cloud point temperature to higher temperatures for this Type I thermoresponsive polymer. When the swelling of the core is prohibited, e.g. by the introduction of sufficient amounts of salt, this behavior disappears.
Similar structures can be prepared using complex coacervate core micelles (C3Ms) built through the interaction of weakly acidic and basic polymer blocks. The advantage of these structures is that two different stabilizing blocks can be incorporated, which allows for more diverse and complex structures and behavior of the micelles.
Using block copolymers with either a polyanionic or a polycationic block C3Ms could be created with a corona which contains two different soluble nonionic polymers, which either have a mixed corona or a Janus type corona, depending on the polymers that were chosen. Using NHS and EDC the micelles could easily be cross-linked by the formation of amide bonds in the core of the micelles. The higher-order self-assembly behavior of these core cross-linked complex coacervate core micelles (C5Ms) was studied. Due to the cross-linking the micelles are stabilized towards changes in pH and ionic strength, but polymer chains are also no longer able to rearrange.
For C5Ms with a mixed corona likely network structures were formed upon the collapse of the thermoresponsive poly(N-isopropylacrylamide) (PNIPAAm), whereas for Janus type C5Ms well defined spherical aggregates of micelles could be obtained, depending on the pH of the solution. Furthermore it could be shown that Janus micelles can adsorb onto inorganic nanoparticles such as colloidal silica (through a selective interaction between PEO and the silica surface) or gold nanoparticles (by the binding of thiol end-groups).
Asymmetric aggregates were also formed using the streptavidin-biotin binding motive. This is achieved by using three out of the four binding sites of streptavidin for the binding of one three-arm star polymer, end-functionalized with biotin groups. A homopolymer with one biotin end-group can be used to occupy the last position. This binding of two different polymers makes it possible to create asymmetric complexes. This phase separation is theoretically independent of the kind of polymer since the structure of the protein is the driving force, not the intrinsic phase separation between polymers. Besides Janus structures also specific cross-linking can be achieved by using other mixing ratios.In den letzten Jahrzehnten war die Herstellung von komplizierten Polymerstrukturen ein wichtiges Forschungsthema für Polymerchemiker. Diese Arbeit behandelt die Synthese von (Blockco-)Polymere, die Herstellung von komplexen und stimulus-responsiven Aggregaten (Mizellen) durch Selbstorganisation, sowie die Vernetzung dieser Strukturen. Auch die Anordnung dieser Mizellen zu Aggregaten mit höherer Ordnung wurde untersucht. Zum Beispiel wird die Bildung von Poly(2-oxazolin) basierter Mizellen in wässriger Lösung und die gleichzeitige Funktionalisierung und Vernetzung dieser Mizellen mittels Thiol-In-Chemie beschrieben. Durch die Einführung von pH-responsiven Gruppen in den Kern der Mizellen konnte der Einfluss von geladenen Gruppen im Kern auf das gesamte Aggregat untersucht werden. Das Einführen von Ladung führt zum Quellen des Mizellkerns und damit zu einer niedrigeren lokalen Konzentration von wasserlöslichem Poly(2-ethyl-2-oxazolin) (PEtOx). Diese niedrigere Konzentration ergibt eine Verschiebung des Trübungspunkt dieses Typ I thermoresponsiven Polymers zu höheren Temperaturen. Wenn die Ausdehnung des Kerns nicht erfolgt, z.B. in Anwesenheit einer hohen Salzkonzentration, findet dieser Effekt nicht statt. Ähnliche Strukturen können mithilfe von Mizellen mit komplexen Koazervatkern (English: Complex Coacervate Core Micelles, C3Ms) durch die Interaktion zwischen Polymeren mit negativ und positiv geladenen Blöcken hergestellt werden. Der Vorteil dieser Strukturen ist, dass zwei verschiedene stabilisierende Polymerblöcke in einem Aggregat vereint werden können, was zur Bildung einer Vielzahl noch komplizierterer Strukturen und zu mehr Responsivität führen kann. Mithilfe von Blockcopolymeren, bestehend aus jeweils einen polyionischen Block und einem neutralen Block (z.B. PEtOx, PEO oder poly(N-isopropylacrylamid) (PNIPAAm)), konnten C3Ms hergestellt werden, in denen zwei neutrale Polymere vereint wurden. Es konnte gezeigt werden, dass diese Polymere sowohl gemischt als auch phasensepariert vorliegen können (letzteres ergibt Janus Mizellen), abhängig welche Polymere gewählt werden. Durch Vernetzung im Kern konnten die Mizellen stabilisiert und fixiert werden (C5Ms). Die Selbstanordnung dieser vernetzten Mizellen zu größeren Aggregaten wurde untersucht. Wenn eine Lösung mit vernetzten Mizellen über den Trübungspunkt von PNIPAAm erhitzt wurde, bildeten sich Netzwerke aus Mizellen mit einer gemischten Korona, während Janus Mizellen sich zu wohldefinierten Aggregaten höherer Ordnung anordneten. Weiterhin konnte gezeigt werden, dass Janus Mizellen sich auf der Oberfläche von anorganischen Nanopartikeln anlagern können; z.B. durch die selektive Wechselwirkung zwischen PEO und Silica oder durch die Adsorption von Thiolgruppen auf Gold-Nanopartikeln. Asymmetrische Aggregate konnten auch mithilfe des Streptavidin-Biotin Komplexes erhalten werden. Durch das Binden der Biotin-Endgruppen eines dreiarmigen Sternpolymeren an eine Streptavidin-Einheit und anschließende Belegung der verbliebenen Bindungsstelle mit der Biotin-gruppe eines Homopolymers, können sehr spezifisch zwei verschiedene Polymere in einem Janus Aggregat vereint werden. Auch die Vernetzung des Streptavidins kann erzielt werden, indem andere Mischverhältnisse gewählt werden.
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Tymichova, Michaela. "Relation between toughness and molecular coupling at cross-linked polymer/solid interfaces." Access electronically, 2005. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20060712.125012/index.html.
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Witte, Judith [Verfasser], Michael [Akademischer Betreuer] Gradzielski, Michael [Gutachter] Gradzielski, and Regine von [Gutachter] Klitzing. "Near surface dynamics of cross-linked and non-cross-linked polymer architectures at solid planar surfaces / Judith Witte ; Gutachter: Michael Gradzielski, Regine von Klitzing ; Betreuer: Michael Gradzielski." Berlin : Technische Universität Berlin, 2021. http://d-nb.info/1238141331/34.
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Al, Lafi Abdul Ghaffar. "Cross linked sulphonated poly (ether ether ketone) for the development of polymer electrolyte membrane fuel cell." Thesis, University of Birmingham, 2009. http://etheses.bham.ac.uk//id/eprint/396/.
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Ion irradiation has been investigated as a route for the preparation of mechanically stable and highly durable cross linked sulphonated PEEK for fuel cell application. The formation of cross linking was confirmed by solvent extraction using the well known Charlsby–Pinner equation. The DSC results indicated that the cross links retard the crystallization, but no changes were observed in the mechanism of crystallization. The thermal kinetic data for irradiated PEEK quantitatively suggest that these films still have sufficient thermal stability for long term applications as fuel cell membranes. Analysis of the dielectric response by Cole-Cole, Havrilak and Negami and Williams and Watts equations indicated that the dipole relaxation was broadened and becoming more asymmetric with cross link density. The sulphonation of the cross linked PEEK in concentrated sulphuric acid indicated that the rate of reaction decreased with cross linking density and was consistent with diffusion control kinetics. Increasing cross link density resulted in more bound water in the equilibrated membranes and the nano-structure present was comparable to that of Nafion. Cross linking improved the chemical stability of PEMs in particular in methanol solution.The measurement of power output and energy efficiency suggested that the cross linked PEMs produced are promising candidates to replace Nafion membranes but more information are required, in particular on their long term stability under fuel cell operating conditions.
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Gaitzsch, Jens, Dietmar Appelhans, Andreas Janke, Maria Strempel, Petra Schwille, and Brigitte Voit. "Cross-linked and pH sensitive supported polymer bilayers from polymersomes: studies concerning thickness, rigidity and fluidity." Royal Society of Chemistry, 2014. https://tud.qucosa.de/id/qucosa%3A36392.
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Polymersomes are at the leading edge of biomedical and nanoparticle research. In order to get closer insights into their mechanical properties, the bilayer forming them needs to be studied thoroughly. Here, we report on the bilayer formation, swelling behaviour, rigidity and fluidity of our membranes derived from pH sensitive and photo-cross-linkable polymersomes.
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Ayres, Neil. "The polymerisation of vinyl monomers via transition metal mediated living radical polymerisation from an insoluble cross-linked polymer matrix." Thesis, University of Warwick, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250975.
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Máša, Bohuslav. "Numerické modelování chování částicového kompozitu se sesíťovanou polymerní matricí." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229477.
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The master's thesis deals with the determination of macroscopic behavior of a particulate composite with cross-linked polymer matrix under tensile load. The main focus of thesis is estimation of mechanical properties of a composite loaded by tensile loading using numerical methods (especially finite elements method). Investigated composite is composed of matrix in a rubbery state filled by alumina-based particles (Al2O3). Hyperelastic properties of the matrix have been modeled by the Mooney-Rivlin material model. Different compositions of particles, their different shape, orientation and different volume fractions have been considered. For all these characteristics of composite numerical models have been developed. The damage mechanisms of the matrix have also been taken into account. Results of numerical analyses have been compared with experimental data and good agreement between numerical models with damage mechanisms of matrix and experimental data has been found.
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You, Therese. "Negative energy elasticity and a model for the behavior of the residual strain in doubly cross-linked gels fabricated by shear strain." Thesis, Uppsala universitet, Polymerkemi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-420125.
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Doubly cross-linked gels were fabricated based on tetra-poly(ethylene glycol) (Tetra-PEG) by shear strain. These are gels with two network structures present in the same polymeric network. The second network structure is introduced by applying a mechanical field to the first natural network structure. These doubly cross-linked gels indicated a negative energy elasticity supporting earlier findings where the energy elasticity was found significantly negative for Tetra-PEG gel. Acquired results indicate implications for past research on the elasticity of polymer gels where the energy contribution was approximated to zero. Obtained results also indicated that the modulus of rigidity for the doubly cross-linked gels is constant regardless of applied shear strain during fabrication. This would indicate that the same second network structure is formed for the interval of 25-800% applied shear strain. The residual strain for the fabricated gels can be well-described using an exponential fitting of the apparent shear modulus of the first network structure and an expression derived from the two-network theory and classic rubber theory. These theories also seem to predict the experimental residual strains for lower strain regions (<100%) quite well. However for larger strain regions (>100%) non-linear effects seem to affect the results causing a deviation. A slight increased modulus of rigidity was noted for the doubly cross-linked gels compared to the regular Tetra-PEG gel. However as the reproducibility of the concluded measurements could not be confirmed during this thesis the results are not conclusive and only indicate the conclusions mentioned above.
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Shams, Es-haghi Siamak. "Mechanics of Tough Chemically Cross-linked Hydrogels." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1430411138.
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Hespel, Louise. "Nouveaux systèmes micellaires intelligents à partir d'huile de lin : synthèse, comportements physico-chimiques et encapsulation." Phd thesis, INSA de Rouen, 2013. http://tel.archives-ouvertes.fr/tel-00924698.
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Les micelles apparaissent comme prometteuses dans le domaine de la vectorisation de médicaments. Afin d'améliorer leur biocompatibilité nous nous intéressons ici à des synthèses originales de copolymères amphiphiles comportant un bloc hydrophobe lipidique biosourcé. Un polymère intelligent constitue le bloc hydrophile. L'huile de lin subit une modification chimique afin d'introduire un site amorceur de polymérisation. Le bloc hydrophile est alors ajouté par polymérisation contrôlée. Deux copolymères sont obtenus, le lipide-b-poly(acide acrylique), pH-sensible et le lipide-b-poly(2-isopropyl-oxazoline), thermo-sensible. Une caractérisation physico-chimique complète révèle des concentrations micellaires critiques basses et des micelles de 10 nm. Un système mixte est préparé par mélange des deux copolymères. L'étude de ce système prouve une sensibilité aux deux stimuli. Afin d'améliorer la stabilité des micelles, nous proposons la photo-réticulation des insaturations de la chaîne lipidique.
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Melnikov, Alexei. "Damage and Fatigue in Cross-Linked Rubbers." University of Akron / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=akron1280198428.
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Barry, John J. A. "A supercritical fluid route to cross-linked polymeric scaffolds." Thesis, University of Nottingham, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.407094.
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Harwood, Eric Alexander. "Chemical synthesis and structural characterization of a nitrous acid interstrand cross-linked duplex DNA /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/8702.
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Zhang, Long. "Infrared Spectroscopic Study of Cross-Linked Polyamines for CO2 Separation." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1367232019.
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Khunniteekool, Chonlada. "Structure/property relationships of cross-linked polyethylene and ethylene vinyl acetate copolymer foams." Thesis, University of Manchester, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390453.
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Read, Elizabeth Sarah. "Synthesis of Primary Amine-based Methacrylic Polymers and Novel Shell Cross-linked Micelles." Thesis, University of Sheffield, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.505573.
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Gräfe, David, Jens Gaitzsch, Dietmar Appelhans, and Brigitte Voit. "Cross-linked polymersomes as nanoreactors for controlled and stabilized single and cascade enzymatic reactions." Royal Society of Chemistry, 2014. https://tud.qucosa.de/id/qucosa%3A36304.
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Polymeric vesicles or polymersomes are one of the supramolecular entities at the leading edge of synthetic biology. These small compartments have shown to be feasible candidates as nanoreactors, especially for enzymatic reactions. Once cross-linked and equipped with a pH sensitive material, the reaction can be switched off (pH 8) and on (pH 6) in accordance with the increased permeability of the polymersome membranes under acidic conditions. Thus cross-linked and pH sensitive polymersomes provide a basis for pH controlled enzymatic reactions where no integrated transmembrane protein is needed for regulating the uptake and release of educts and products in the polymersome lumen. This pH-tunable working tool was further used to investigate their use in sequential enzymatic reactions (glucose oxidase and myoglobin) where enzymes are loaded in one common polymersome or in two different polymersomes. Crossing membranes and overcoming the space distance between polymersomes were shown successfully, meaning that educts and products can be exchanged between enzyme compartments for successful enzymatic cascade reactions. Moreover the stabilizing effect of polymersomes is also observable by single enzymatic reactions as well as a sequence. This study is directed to establish robust and controllable polymersome nanoreactors for enzymatic reactions, describing a switch between an off (pH 8) and on (pH 6) state of polymersome membrane permeability with no transmembrane protein needed for transmembrane exchange.
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Alhwaige, Almahdi A. "NOVEL BIOBASED CHITOSAN/POLYBENZOXAZINE CROSS-LINKED POLYMERS AND ADVANCED CARBON AEROGELS FOR CO2 ADSORPTION." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1396437860.
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Gao, Hongrong. "Stabilisation des Membranes Perfluorosulfoniques par Réticulation et Développement de Membranes Composites Inorganique-organique. Application aux Piles à Combustible à Moyenne Température." Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20236.
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Ce travail décrit le développement de membranes réticulées et de membranes composites inorganique-organique basées sur des polymères perfluorosulfoniques (PFSA) à chaîne longue (LSC) et courte (SSC) et à faible masse équivalente, pour application dans une pile à combustible fonctionnant à moyenne température et à faible humidité relative. Des membranes (LSC-PFSA) réticulées par des groupements sulfonimide ont été préparées à partir de membranes fonctionnalisées par des groupements fluorure de sulfonyle. Les membranes réticulées de type SSC-PFSA ont été préparées à partir d'un polymère à chaînes 2-bromo-1,1,2,2-tetrafluoroéthoxy pendantes et réticulables, par traitement thermique pour former des ponts perfluoro. Les membranes préparées ont été caractérisées par spectroscopies IR, Raman, RMN et XPS, par MEB-EDX et ATG. Les membranes de LSC-PFSA et SSC-PFSA réticulées présentent une stabilité dimensionnelle accrue et une meilleure performance en pile à combustible hydrogène-oxygène jusqu'à 110°C que celles des membranes de PFSA non modifiées. Une procédure d'échange ionique/précipitation a été utilisée pour la préparation de systèmes composites à partir de membranes de LSC-PFSA et SSC-PFSA. Plusieurs techniques ont été utilisées pour caractériser les matériaux préparés. Les membranes de type SSC-PFSA-ZrP présentent une morphologie distincte, et différente de celle des membranes LSC-PFSA-ZrP. En pile à combustible, ces membranes composites autorisent une température de fonctionnement plus élevée et une humidité relative plus faible, que les membranes non modifiéesThe objective of this research was to develop cross-linked and composite inorganic-organic membranes based on long and short side chain (LSC, SSC) perfluorosulfonic acid (PFSA) polymers with low equivalent weight/high ion exchange capacity for operation at medium temperature and low relative humidity in proton exchange membrane fuel cells. Covalently cross-linked LSC-PFSA membranes were prepared from sulfonyl fluoride form membranes by reaction with an ammonium base followed by thermal processing to give cross-linking through sulfonimide groups. Covalently cross-linked SSC-PFSA membranes were prepared by formation of perfluoro-cross-links under thermal treatment of solution cast polymers containing cross-linkable 2-bromo-1,1,2,2-tetrafluoroethoxy side chains. Evidence for cross-linking was provided by IR, Raman, NMR and XPS spectroscopies, SEM-EDX, tensile testing and TGA. Cross-linked LSC and SSC-PFSA membranes have increased dimensional stability and improved performance in a single hydrogen-oxygen cell fuel up to 110°C compared with the corresponding non-cross-linked membranes. Composite PFSA-zirconium phosphate membranes, based on LSC and SSC PFSA (or cross-linked PFSA) membranes were prepared using an ion exchange/precipitation procedure. The physical properties of LSC-PFSA-ZrP and SSC-PFSA-ZrP have been compared and the morphology of the composite membranes shown to differ in SSC and LSC membranes. Composite membranes enabled fuel cell operation at higher temperature/lower RH than non-composite PFSA. Preliminary results indicated that association of cross-linking and composite membrane formation is a clear future perspective of this work
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Alghunaim, Abdullah. "Immobilization of Poly(N-Isopropylacrylamide) on Hydroxylated Surfaces Using Cross-linked Organosilane Networks." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1467858917.
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Liu, Fangyao [Verfasser], and Franz Xaver [Akademischer Betreuer] Schmid. "Linear and Cross-linked UCST-Type Polymers : Synthesis and Properties / Fangyao Liu. Betreuer: Franz Xaver Schmid." Bayreuth : Universität Bayreuth, 2015. http://d-nb.info/1075807840/34.
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Xie, Wa. "Surface Topography and Aesthetics of Recycled Cross-Linked Polyethylene Wire and Cable Coatings." Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc799512/.
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Our research focuses on re-using a waste a material, cross-linked polyethylene abbreviated XLPE, which is a widely used coating for wires. XLPE is strong and has excellent thermal properties due to its chemical structure - what leads to the significance of recycling this valuable polymer. Properties of XLPE include good resistance to heat, resistance to chemical corrosion, and high impact strength. A wire is usually composed of a metal core conductor and polymeric coating layers. One creates a new coating, including little pieces of recycled XLPE in the lower layer adjacent to the wire, and virgin XLPE only in the upper layer. Industries are often wasting materials which might be useful. Mostly, some returned or excess products could be recycled to create a new type of product or enable the original use. This method helps cleaning the waste, lowers the costs, and enhances the income of the manufacturing company. With the changing of the thickness of the outer layer, the roughness changes significantly. Moreover, different processing methods result in surfaces that look differently.
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Over, Lena Charlotte [Verfasser], and M. A. R. [Akademischer Betreuer] Meier. "Sustainable Derivatization of Lignin and Subsequent Synthesis of Cross-Linked Polymers / Lena Charlotte Over ; Betreuer: M. A. R. Meier." Karlsruhe : KIT-Bibliothek, 2017. http://d-nb.info/1140118439/34.
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Tran-Math, Carolyn. "Synthesis of poly(NIPAM-co-vmbpy) microspheres and transition metal monomers for metallopolymeric material construction." Scholarly Commons, 2014. https://scholarlycommons.pacific.edu/uop_etds/271.
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Poly-N-isopropylacrylamide (PNIPAM) gels grafted to redox-active metal monomers undergo sudden expansion-contraction activity in response to change in environmental conditions, such as temperature, pH, ion concentration, and oxidation states of the metal. The relevance of these conditions to biological systems has garnered attention for PNIPAM-based polymer as potential biomedical materials. Candidate transition metal monomers containing ruthenium and nickel cores were designed and synthesized for copolymerization with NIPAM and cross-linker methylene-bis-acrylamide in order to attain metallopolymer microspheres with a high percentage of metal incorporation. Synthesis of 4-vinyl-4'-methyl-2,2'-bipyridine (vmbpy) was optimized from literature procedures for usage in the metal-containing monomers. Metal-containing monomers were then synthesized, purified, and characterized using electrospray ionization mass spectrometry (ESI-MS), proton nuclear magnetic resonance ( 1 H-NMR), X-ray diffraction, Ultraviolet-Visible light (UV-Vis) spectroscopy, and spectrofluorometry. While the Ru complex was pure and exhibited interesting photochemical properties, lability of the ligands on the Ni monomers resulted in complication of their synthesis. Polymer microspheres of poly(NIPAM-co-vmbpy), the cross-linked copolymer constructed from NIPAM and vmbpy monomers, were synthesized from modified emulsion polymerization procedures. Experimental setup parameters and conditions—such as the methods of injection of initiator and stirring, the time duration for incubating the emulsion, and the initiation temperature—were varied to assess their influences on the material properties of the final product. The polymers were tested for size and morphological uniformity by dynamic light scattering (DLS) and scanning electron microscopy (SEM). While varying the method of initiator injection had no measurable effect on the product, strong mechanical stirring and incubation of the polymer emulsion for 15-25 minutes at 71 °C procured similar polymer products. Consistent properties ensured the polymers' suitability for further material development. Preliminary morphological and spectroscopic characterization was conducted of metallopolymers made from Ru and Ni grafted to PNIPAM. Metallopolymers containing polypyridyl Ru cores exhibited desirable spectroscopic properties and spherical morphology.
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Saxena, Shubham. "Nanolithography on thin films using heated atomic force microscope cantilevers." Thesis, Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-08302006-223629/.
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"Controlled fabrication of cross-linked polymer films using low energy hydrogen(+) ions." 2003. http://library.cuhk.edu.hk/record=b6073553.
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"August 2003."Thesis (Ph.D.)--Chinese University of Hong Kong, 2003.
Includes bibliographical references.
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Mode of access: World Wide Web.
Abstracts in English and Chinese.
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Tsai, Yi-Yuan, and 蔡亦媛. "Cross-linked composite polymer electrolyte using surface modified mesoporous silica MCM-41." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/54116249824954020621.
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碩士國立中央大學
化學研究所
91
The thesis divided into two parts. First, we are interested that the effect of addition of Mesoporous silica MCM-41 with surface modification of (3-glycidyloxypropyl)trimethoxysilane (GLYMO) to poly(ethylene oxide) (PEO) complexed with LiClO4 has been explored by alternating current (AC) impedance, powder X-ray diffraction (XRD) , differential scanning calorimeter (DSC), and multinuclear solid-state NMR measurements. The presence of small quantity of GLYMO modified MCM-41 enhances the ionic conductivity of the resulting composite electrolyte as compared to present PEO/LiClO4 electrolyte. The enhancement in conductivity is directly correlated with the improved compatibility between PEO and surface modified MCM-41 as a result of blending PEO with GLYMO group. Addition of high concentration of surface modified MCM-41 leads to a decrease in the conductivity of the composite electrolyte, mainly because MCM-41 filler acts an insulator that impedes the lithium ion transport. DSC results show that both the polymer segmental motion and the proportion of amorphous PEO phase are affected by addition of MCM-41 filler. The change of portion of crystalline PEO phase can be explained by Lewis acid-base interactions between PEO chain, MCM-41 surface, and lithium cation. Solid-state 7Li NMR measurements show that the 7Li linethwidth narrowing begins at temperature much lower than the glass transition temperature of PEO chains, indicative of the presence of an additional conduction mechanism with lithium ions moving along (both interior and exterior) the mesoporous channels of MCM-41.The additional mechanism is unique for the composite electrolytes doped with mesoporous silica MCM-41, and is absent in the case of other spherical fillers such as Al2O3 and SiO2 particles in PEO-based electrolytes. Variable temperature proton decoupled 7Li MAS (magic angle spinning) NMR spectra reveal that at least two different lithium environments are present in the composite electrolyte, serving as an evidence for the existence of interaction between lithium cation and MCM-41 surface. In the second part of my thesis, the effect of addition of uncalcined or calcined mesoporous silica MCM-41 to poly(ethylene oxide) (PEO) complexed with LiClO4 has been explored by alternating current (AC) impedance, powder X-ray diffraction (XRD) , differential scanning calorimeter (DSC), and multinuclear solid-state NMR measurements. The present of small quantity of uncalcined MCM-41 do not enhance the ionic conductivity of the resulting composite electrolyte as compared to present PEO/LiClO4 electrolyte. However, the present of small quantity of calcined MCM-41 enhances the ionic conductivity of the resulting composite electrolyte as compared to present PEO/LiClO4 electrolyte. The enhancement in conductivity is directly correlated with Lewis acid-base interactions between PEO chain, MCM-41 surface, and lithium cation. Addition of high concentration of uncalcined or calcined MCM-41 leads to a decrease in the conductivity of the composite electrolyte, mainly because uncalcined or calcined MCM-41 filler acts an insulator that impedes the lithium ion transport. Variable temperature proton decoupled 7Li MAS (magic angle spinning) NMR spectra reveal that at least two different lithium environments are present in the composite electrolyte, serving as an evidence for the existence of interaction between lithium cation and MCM-41 surface.
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Jiwpanich, Siriporn. "Design and synthesis of a new class of self-cross-linked polymer nanogels." 2011. https://scholarworks.umass.edu/dissertations/AAI3465020.
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The design and engineering of nanoscopic drug delivery vehicles that stably encapsulate lipophilic drug molecules, transport their loaded cargo to specific target sites, and release their payload in a controlled manner are of great interest in therapeutic applications, especially for cancer chemotherapy. This dissertation focuses on chemically cross-linked, water-soluble polymer nanoparticles, termed nanogels, which constitute a promising scaffold and offer the potential to circumvent encapsulation stability issues. A facile synthetic method for a new class of self-cross-linked polymer nanogels, synthesized by an intra/intermolecular disulfide cross-linking reaction in aqueous media, is described here. This simple emulsion-free method affords noncovalent lipophilic guest encapsulation and surface functionalization that may allow for targeted delivery. The encapsulation stability of lipophilic molecules sequestered within these nanoscopic containers is evaluated by a fluorescent resonance energy transfer (FRET) based method developed by our research group. We demonstrate that the encapsulation stability of noncovalently encapsulated guest molecules in disulfide cross-linked polymer nanogels can be tuned and that guest release can be achieved in response to a biologically relevant stimulus (GSH). In addition, varied hydrophobicity in the self-cross-linked nanogels affects the lipophilic loading capacity and encapsulation stability. We reveal that optimal loading capacity is limited by encapsulation stability, where over-loading of lipophilic molecules in the nanoscopic containers may cause undesirable leakage and severely compromise the viability of such systems for drug delivery and other biological applications.
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Hsiao, Ming-Chieh, and 蕭明傑. "Synthesis of Cross-linked Polymer Supported Vanadium Complexes and Their Application on Catalysis." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/35178229887442933776.
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碩士臺灣大學
化學研究所
98
The main focus of this study is to immobilize the catalysts on the solid supports and make them recyclable. Compared with the general inorganic supports, the cross-linked polymer supports promoted the activities of the catalysts by providing the affinity with the reactants. Here, we synthesized poly(methyl acrylate) with different chain lengthes via atom transfer radical polymerization (ATRP), and turned it into more stable material by reaction with two kind of cross-linker CL1 and CL2 respectively, and then hydrolyzed the ester group into the carboxylate functional group under basic aqueous solution, followed by reaction of VOSO4 under neutral aqueous solution to afford the insoluble polymer complexes, which were characterized by IR、solid UV、and ICP-MASS。 This complex could be used to catalyze cyclooctene into cyclooctene oxide completely with TBHP (tert-butyl hydroperoxide) under 60 ℃ in 15hr, and the same experiment result could be reached by replacing TBHP with KHSO5 at the room temperature. Besides, a series of oxidation of olefins were performed under similar reaction condition, and the final products gave either the diols or the acids from the oxidative cleavage depending on the amounts of the oxidants used in the reaction. This type of catalyst would remain in the water layer and still mantained 90 ％ activity after 5 times recycled.
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朱俊嘉. "Cross-Linked Polymer Materials for Nonlinear Optics Cured Acrylic Monomer Bearing Azobenzene Dye." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/53593854241266848954.
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碩士輔仁大學
化學學系
85
A new thermoseting second-order nonlinear optical (NLO) polymer was synthesized from 4'-[[[2-(methacryloyloxy)ethyl]- ethyl]amino]-4-nitroazobenzene (DRIM), MMA, and a crosslinking agent (I), di(ethylene glycol) dimethacrylate. The NLO molecule, DRIM was systhesized from Disperse Red I and methacryloyl chloride. This polymer was then crosslinked by thermal process under electric field poling. The crosslinked polymers containing higher content of crosslinking agent exhibited a higher Tg and Td, and the decay speed of their second-harmonic generation signal also lowered. From the DSC analyses, the crosslinked polymers depending on the amount of crosslinking agent I exhibited higher Tg values ranging from 120℃ to 256℃, and the Td values also varied from 225℃ to 302℃, as detected by TGA analyses. When the crosslinked polymer containing 60wt% crosslinking agent I, its NLO property can retain up to 80% at 120℃, and can retain up to 60% at 80℃ after 192 hours. Another thermoseting polymer system was synthesized from 4'-[[2-(acryloyloxy)ethyl]ethyl]ethylamino]-4-nitroazobenzene (DRIA), MA, and crosslinking agent II, pentaerythritol tetraacrylate. With incorporating of 20wt% crosslinking agent II, the NLO property of the crosslinked polymers can remain up to 70% at 120℃.
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Yun-TseLin and 林昀澤. "Synthesis and Behavior of Cross-Linked Gel Polymer Electrolytes in Various Degrees for Lithium Batteries." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/bn4x85.
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Chang, Ruei-Gang, and 張睿罡. "Sensitivity Improvement of Single Fiber SERS Sensor Based on Surface Modification of Cross-linked Polymer." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/34109967861447445390.
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Alghunaimi, Fahd. "The Performance of a Thermally Cross-Linked Polymer of Intrinsic Microporosity (PIM-1) for Gas Separation." Thesis, 2013. http://hdl.handle.net/10754/293323.
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Gas transport properties of PIM-1 (the first ladder polymer with intrinsic microporosity) and TC-PIM-1 (thermally cross-linked PIM-1) at 35°C and different pressures were thoroughly studied. The purpose of this study was to evaluate and compare the performance of the TC-PIM-1 membranes with PIM-1 for natural gas separation. The TC-PIM-1 polymer was prepared by post-modification of PIM-1 at 300°C for a period of two days. Sorption isotherms of seven gases, including N2, O2, CH4, CO2, C2H6, C3H8 and n-C4H10, were determined for PIM-1 and TC-PIM-1 using the dual-volume barometric sorption technique at 35°C at different pressures. The sorption isotherms followed the dual-mode sorption model, which is typical for glassy polymers. Moreover, permeability (P) of eight gases, including He, H2, N2, O2, CH4, CO2, C3H8 and n-C4H10, were determined for PIM-1 and TC-PIM-1 at 35°C and 2.0 atm. Furthermore, average diffusion coefficients (D ̅) were calculated from the permeability and solubility data for all tested gases for both polymers. The sorption (S), permeability (P) and average diffusion coefficients (D ̅) for the TC-PIM-1 membrane exhibited lower values than the PIM-1 membrane. However, the TC-PIM-1 membrane showed exceptional gas separation performance. The TC-PIM-1 membrane had a helium (He) permeability of 1218 barrer with He/CH4 and He/N2 ideal selectivities of 27.1 and 23.9 respectively, and carbon dioxide (CO2) permeability of 1088 barrer with CO2/CH4 and CO2/N2 ideal selectivities of 24.2 and 21.3 respectively. Additionally, the TC-PIM-1 membrane showed a hydrogen (H2) permeability of 2452 barrer with an ideal H2/CH4 selectivity of 54.5.
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Brummelhuis, Niels ten [Verfasser]. "Self-assembly of cross-linked polymer micelles into complex higher-order aggregates / von Niels ten Brummelhuis." 2011. http://d-nb.info/101425597X/34.
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Cao, Fong-Yi, and 曹&;#23791;溢. "Self-Assembled and Cross-Linked Fullerene Interlayer on Titanium Oxide for Highly Efficient Inverted Polymer Solar Cells." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/64847237905648388663.
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碩士國立交通大學
應用化學系分子科學碩博士班
99
This research contains two independent parts, the first part is self-assembled and cross-linked fullerene interlayer on titanium oxide for highly efficient inverted polymer solar cells, and the second part is morphological stabilization by incorporation of a pentafluoro phenyl-containing fullerene for highly stable oganic solar cells. In first part, we used two oxetane-functionalized fullerene derivatives, [6,6]-phenyl-C61-butyric oxetane ester (PCBO), and [6,6]-phenyl-C61-butyric oxetane dendron ester (PCBOD) in the inverted solar cells to achieve higher power conversion efficiency. We demonstrated that the oxetane functionality with neutral nature can anchor onto the TiOx surface via cationic ring-opening reaction under thermal and UV treatment, as evidenced by the contact angle measurement and x-ray photoelectron spectroscopy. The self-assembly of PCBO, functionalized with one oxetane group, on the TiOx surface forms an adhesive monolayer with intimate contact. Inverted bulk-heterojunction device B (ITO/TiOx/SA-PCBO/P3HT:PCBM(1:1, w/w)/MoO3/Ag) with this self-assembled PCBO (SA-PCBO) modifier showed an impressive power conversion efficiency of 4.1%, which outperforms the reference device A (PCE = 3.6%) without this monolayer (ITO/TiOx/P3HT:PCBM(1:1, w/w)/MoO3/Ag). This SA-PCBO modifier exerts multi-positive effects on the interface, including improvement of exciton dissociation efficiency, reduction of charge recombination, decrease of the interface contact resistance and passivation of the surface electron-traps at the interface of TiOx. Furthermore, PCBOD, containing two oxetane groups, is capable of self-assembling on the TiOx surface and simultaneously undergoing cross-linking, generating a dense, robust and pinhole-free multi-molecular interlayer to further strengthen the interface characteristics. Device C (ITO/TiOx /C-PCBOD/P3HT:PCBM(1:1, in wt%)/MoO3/Ag) incorporating this cross-linked PCBOD (C-PCBOD) interlayer delivered the highest PCE of 4.5% which represents 26% enhancement over device A. This simple and easy strategy smartly integrates the advantages of self-assembly and cross-linking in a single fullerene-based molecule, showing promise in producing highly efficient inverted PSCs. A primary area of concern for traditional P3HT:PC61BM system is the morphological instability. Upon heating, spherical PCBM with high molecular mobility tends to diffuse out of the P3HT matrix and aggregate into larger cluster or single crystals. Such a progressive phase-segregation eventually leads to micron-sized D-A domains with concomitant reduction of device efficiency. In the second part, we have designed a pentafluorophenyl-containing fullerene -[6,6]-phenyl-C61-butyric pentafluorophenyl ester (PCBFP) which was doped into the P3HT:PC61BM active layer to form a ternary blending system. Physical polymerization through the attractive quadrupole-quadrupole interaction between pentafluorophenyl groups and C60 core-structure was demonstrated to effectively prevent the thermal-driven phase separation. The device based on the P3HT:PCBM:PCBFP(6:5:1 in wt %) blend showed extremely stable device characteristics, delivering an average power conversion efficiency (PCE) of 3.7 % during the long-term thermal heating at 150 ℃ for 25 hours.
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Zieren, Shelley Marie. "Synthesis of cross-linked sulfonated polysulfone and mechanical properties of SPEEK-based membranes for direct methanol fuel cells." Thesis, 2011. http://hdl.handle.net/2152/ETD-UT-2011-05-3418.
Full textAbstract:
Direct methanol fuel cells (DMFC) are being investigated for use as low-power electrochemical energy conversion devices. These types of fuel cells can be useful for portable electronics. The polymer electrolyte membrane plays a critical role in the overall performance of DMFC. The commercially available membrane, Nafion, suffers from high methanol permeability and a resulting methanol crossover from the anode to the cathode; it is also expensive. Accordingly, alternative membrane materials, such as sulfonated hydrocarbons, are intensively pursued for DMFC. For example, sulfonated poly (ether ether ketone) (SPEEK) and sulfonated polysulfone (SPsf) are two such candidates.
This thesis focuses first on a simple synthesis method for a cross-linked sulfonated polysulfone membrane. Sulfonated polysulfone (Psf) membranes, with high IEC (1.4 - 2.2 meq/g), were characterized by nuclear magnetic resonance spectroscopy (NMR), proton conductivity, and water uptake. The degree of sulfonation was calculated by NMR and verified by acid-base titration analysis. Although the membranes showed good proton conductivity, they suffered from excessive swelling at high temperatures. Furthermore, the post-sulfonation of a carboxyl-substituted polysulfone (Psf-COOH) was carried out with trimethylsilyl chlorosulfonate, and solubility issues of the Psf-COOH in chlorinated solvents led to difficulty in controlling the degree of sulfonation (DS) and in purification. Accordingly, this approach to cross-linking sulfonated polysulfone was rejected as a viable method.
This thesis then focused on the investigation of the mechanical properties of acid-base blend membranes based on SPEEK and heterocycle-tethered Psf and cross-linked membranes based on SPEEK that were previously reported by our group; these membranes were known to exhibit good performance in DMFC. However, the assessment of the mechanical stability of any new membranes developed is critical for their practical viability in DMFC. Accordingly, the mechanical strength and ductility of these membranes were investigated and compared for various membrane compositions. The acid-base blend membranes investigated consisted of SPEEK (acidic polymer) and a heterocycle-tethered Psf (basic polymer); for example, blends consisting of SPEEK and amino-benzimidazole-tethered Psf (SPEEK/Psf-ABIm) and SPEEK and benzotriazole tethered Psf (SPEEK/Psf-Btraz) were investigated. The cross-linked SPEEK was made by Friedel-Craft acylation with Psf-COOH (DS = 1 or 2). The two blend membranes showed superior mechanical properties compared to Nafion 115 and comparable to plain SPEEK. The crosslinked membranes showed good mechanical properties and better strength than Nafion 115, but they were more brittle than both Nafion 115 and plain SPEEK. Further optimization of cross-linking conditions is necessary to produce the best performing membrane.text
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Vengala, Kalyan Chakravarthy. "Building a modified impedance tube for measurement of sound transmission loss and absorption coefficients of polymer cross-linked aerogel core composites." 2009. http://digital.library.okstate.edu/etd/Vengala_okstate_0664M_10589.pdf.
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Chakraborty, Twarita. "Molecularly Imprinted Polymers Based On Fluorescent And Template Binding Cross-Linker." Thesis, 2007. http://etd.iisc.ernet.in/handle/2005/2006.
Full textAbstract:
The synthesis of materials with molecular recognition properties has become a topic of great technological and scientific interest. Molecular imprinting is one of the most effective strategies in preparing highly selective synthetic receptors. The technique of molecular imprinting involves the copolymerization of functional and cross-linking monomers in the presence of a molecular template. Following polymerization and subsequent removal of the template, the molecularly imprinted polymer (MIP) retains a “molecular memory” of the template. During rebinding, the resultant polymer shows higher affinity and selectivity towards the molecular template when compared to other structural analogs. Ease of preparation and high thermal and chemical stability of this class of materials offers a broad range of potential applications. Promising areas of application include separation, chromatography, catalysis, sensors, antibody mimics, and drug delivery etc.
The thesis entitled “Molecularly Imprinted Polymers based on Fluorescent and Template binding Cross-linker” deals with the design and synthesis of several molecularly imprinted polymers (MIPs) using different functional and cross-linking monomers, the main focus being use of preformed template-monomer complex, use of fluorescent cross-linker and development of functional group containing cross-linker.
Chapter 1: An Introduction to Molecularly Imprinted Polymers.
The first chapter provides an introduction to the field of molecularly imprinted polymers. It presents an overview of molecular imprinting process including a brief history of its discovery and its evolution to the present form. This chapter further elaborates on the principle of molecular imprinting with an emphasis on different parameters that directly affect their performance. It also provides a brief review of the applications of molecularly imprinted polymers.
Chapter 2: Highly Cross-linked Metal Ion Imprinted Polymers.
The second chapter deals with the synthesis of series of highly cross-linked metal-ion imprinted polymers. The process of metal ion-imprinting usually involves carrying out the polymerization and cross-linking directly in presence of the appropriate metal ion. In the present study, chemical-immobilization method was adopted which involves the use of preformed metal complexes with polymerizable group for the imprinting. Acrylate complexes of various metal-ions, such as Cu2+, Zn2+, Co2+, Ni2+, Pb2+ and Cr3+, were synthesized prior to polymerization. These pre-assembled complexes were then used to prepare MIPs, in the anticipation that this would lead to enhanced selectivity. Ethyleneglycol dimethacrylate (EGDMA) was used as the cross-linking monomer. As a control, the respective non-imprinted polymers (NIPs) were also made in absence of the template metal ion. Following polymerization, the template metal ion was extracted from the resultant metal ion-imprinted polymer. The selectivity of the metal ion-imprinted polymers was examined by a batch process using analytical tools, such as, Atomic Absorption Spectroscopy (AAS) and Inductively Coupled Plasma Spectroscopy (ICP). The spectroscopic studies revealed significant selectivity of all the MIPs towards the template metal ion. Among all six metal ion-imprinted polymers, Pb2+ and Cr3+ ion-imprinted polymer showed remarkable selectivity, followed by Cu2+ and Zn2+ ion-imprinted polymers. The Co2+ and Ni2+ ion-imprinted polymers exhibited comparatively poor selectivity. Representative plots depicting the selectivity exhibited by Pb2+ and Cr3+ ion-imprinted polymers are shown in Figure 1. These observations were rationalized based on the size and geometric preferences imposed by the imprinted site on the ion that binds to it.
Figure 1. Selectivity study for (a) Pb2+ ion-imprinted polymer, (b) Cr3+ ion-imprinted polymer.
Chapter 3. Molecularly Imprinted Fluorescent Chemosensor for Copper (II).
Cu(II) is a source of important pollutant and therefore, the development of sensors that can detect Cu(II) selectively as well as remove Cu(II) from contaminated samples is an important objective. The use of molecular imprinting technique is an appealing approach in this regard. For this, a fluorophore containing cross-linker, namely 9,10-bis-(acryloyloxymethyl)anthracene (BAMA) was synthesized. This fluorescent cross-linker was used along with the standard cross-linker, EGDMA, for preparing Cu2+ ion-imprinted polymer. The complex of copper methacrylate (Cu-MAA) was prepared prior to polymerization used for the preparation of MIP. The resultant imprinted polymer exhibited quenching of the fluorescence in presence of Cu2+ ion, both in organic and aqueous medium. The efficiency of quenching of NIP (prepared in absence of Cu2+ ion) was significantly lower than that of MIP. A typical stack spectra showing the quenching process, along with a comparison of the quenching efficiency of MIP and NIP is shown in Figure 2.
The imprinted polymers showed significant selectivity over other non-template metal ions, thereby reaffirming the importance of the imprinting process. The sensitivity of the fluorescence detection could be enhanced by increasing the level of the fluorophore incorporation. The increased sensitivity in detecting Cu2+ ion, demonstrated by the MIP suggests that a statistically random incorporation of the fluorophore into MIP matrices could be a useful approach for imparting a sensing element to MIPs.
Figure 2. Fluorescence spectra of the (a) imprinted (MIP-1) and (b) non-imprinted (NIP-1) polymers in the presence of various concentration of Cu(OAc)2 in methanol. (c) Comparison of quenching efficiency of MIP-1 and NIP-1. Data were collected 3 h after addition of copper solution. I0 and I are the fluorescence intensities at 399 nm of the polymers in the absence presence of copper respectively. Two individual runs are presented in (c).
Chapter 4. Molecularly Imprinted Turn-Off-On Sensor.
This chapter describes the design and synthesis of molecularly imprinted fluorescent turn-off-on sensor utilizing the same fluorescent cross-linker, BAMA. Combining the process of fluorescence resonance energy transfer (FRET) with molecular imprinting technique, a novel turn-off-on sensor was developed. A molecularly imprinted polymer was prepared using a fluorescent template Coumarin-30 (C-30). C-30 was chosen as the template to ensure a significant overlap of the emission spectra of BAMA and the absorption spectra of C-30, thereby optimizing for FRET.
Figure 3. Structures of relevant molecules.
The C-30 imprinted polymer exhibited simultaneous quenching in fluorescence (turn-off) of BAMA and enhancement in fluorescence (turn-on) of C-30 (Figure 4). The imprinted polymer showed significantly better performance over the non-imprinted polymer (NIP).
Figure 4. Fluorescence spectra of the (a) imprinted (MIP) and (b) non-imprinted (NIP) polymers with increasing concentration of the template Coumarine-30 in methanol.
The UV-vis studies revealed that the more effective quenching is indeed due to the affinity for C-30 exhibited by the higher binding imprinted polymer. The imprinted polymer also showed significant selectivity over structurally analogous molecules. Therefore, both high sensitivity and selectivity were realized in such novel off-on sensor. Extension of this concept to other biologically relevant fluorescent templates could lead to potentially useful applications.
Chapter 5. Design of New Template Binding Cross-linker.
In molecularly imprinted polymers (MIP), high cross-linking density (~80 to 90 mole percent) is essential to ensure high selectivity, which limits the functional (binding) monomer to about 10-20 mole percent. Methacrylic acid (MAA) and ethyleneglycol dimethacrylate (EGDMA) are the most common combination of functional monomer and cross-linker, respectively, used in molecular imprinting. Generally a molecularly imprinted polymer made with this combination, contains only 10-20% binding sites. This limitation of binding site density is an aspect that has largely been overlooked. In order to improve the efficiency of MIP materials by enhancing the number of binding sites, a new cross-linking monomer (CYDI, 1) with two carboxylic acid groups was designed and synthesized by coupling itaconic anhydride with cyclohexane dimethanol (Figure 5).
Figure 5. Structures of relevant molecules. The new functional group bearing cross-linking monomer (1) Itaconate ester of cyclohexanedimethanol (CYDI), the template (2) theophylline (Theop) and the structural analogue of template (3) caffeine (Caff).
This new cross-linking monomer was then employed for preparing molecularly imprinted polymer using a drug molecule, theophylline (Theop 2, a bronchodilator) as the template. Seven molecularly imprinted polymers were synthesized with different ratios of CYDI and EGDMA, keeping the cross-linking density constant. The binding efficiency and the selectivity of these imprinted polymers were thoroughly investigated. It was seen that while saturation binding values for theophylline increased continuously with functional cross-linker (CYDI) content, the optimum selectivity with respect to analogous substrate, caffeine, was attained at 40 mol% CYDI. These studies suggest that the approach of using functional group containing cross-linkers could lead to improved MIP performance.
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Pereira, Nelson. "Synthesis of novel linear and cross-linked polymers." 2007. http://hdl.handle.net/1993/20534.
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Mabire, A. B., Q. Brouard, Anaïs Pitto-Barry, R. J. Williams, H. Willcock, N. Kirby, E. Chapman, and R. K. O'Reilly. "CO2/pH-responsive particles with built-in fluorescence read-out." 2016. http://hdl.handle.net/10454/15381.
Full textAbstract:
yesA novel fluorescent monomer was synthesized to probe the state of CO2-responsive cross-linked polymeric particles. The fluorescent emission of this aminobromomaleimide-bearing monomer, being sensitive to protic environments, can provide information on the core hydrophilicity of the particles and therefore indicates the swollen state and size of the particles. The particles’ core, synthesized from DEAEMA (N,N-diethylaminoethyl methacrylate), is responsive to CO2 through protonation of the tertiary amines of DEAEMA. The response is reversible and the fluorescence emission can be recovered by simply bubbling nitrogen into the particle solution. Alternate purges of CO2 and N2 into the particles’ solution allow several ON/OFF fluorescence emission cycles and simultaneous particle swelling/shrinking cycles.
British Petroleum Company (BP), Engineering and Physical Sciences Research Council (EPSRC)