Dissertations / Theses on the topic 'Copolymers'
To see the other types of publications on this topic, follow the link: Copolymers.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Copolymers.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Thunga, Mahendra. "Rheological and Mechanical behaviour of Block copolymers, Multigraft copolymers and Block copolymer Nanocomposites." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-19634.
Full textAbstract:
Block copolymers are commercially significant and fundamentally interesting class of polymeric materials. The ability to undergo interfacial thermodynamics-controlled microphase separation from a completely disordered state in the melt to a specifically defined ordered structure through self-organization makes the block copolymers based materials unique. Block copolymer are strongly replacing many of the commercially available polymers due to their unique microstructure and properties. The most practical interests of block copolymers lie in the area of thermoplastic elastomers (TPEs). The objective of the present thesis work is to developing novel roots for enhancing the physical and mechanical properties in block copolymer and multigraft copolymers. Initially the properties are tailored by controlling chemical architecture at synthesis level and by selective blending at production level. This gives an easy access for improvement of the material properties and this is one of my major tasks in the present research modules.
Further the block copolymer based TPEs are cross-linked in presence of electron beam (EB) radiation for developing materials with superior properties. The electron beam radiation has the ability to alter material parameters at molecular level for enhancing the macroscopic properties. The desirable physical and chemical properties can be easily attained by varying the radiation beam parameters. In addition to that, controlling the material at nanometer scale is one of the greatest challenges for current nanocomposite research. In elastomeric materials it is very prominent to fill the rubber matrix with nano particles from carbon or silica by melt mixing technique for enhancing the material properties. Other than conventional melt mixing technique, sol–gel processing is also a versatile technique, which making it possible to produce a wide variety of materials and to provide existing materials with novel properties. A combination of in situ sol-gel reaction with electron beam cross-linking in TPEs from triblock copolymer has been demonstrated for the first time as one of the novel nanocomposite system in this work. The main advantage of this system lies in controlling the material behaviour by finely tuning the size of silica nano particle generated inside TPE during in situ sol-gel reaction. Finally, the various roots employed for enhancing the material behaviour in block copolymers in the above research module were secussfully employed on super elastic multigraft copolymers for improving their strength withour sacrificing the super elastic nature.
2
Thunga, Mahendra. "Rheological and Mechanical behaviour of Block copolymers, Multigraft copolymers and Block copolymer Nanocomposites." Doctoral thesis, Technische Universität Dresden, 2008. https://tud.qucosa.de/id/qucosa%3A25047.
Full textAbstract:
Block copolymers are commercially significant and fundamentally interesting class of polymeric materials. The ability to undergo interfacial thermodynamics-controlled microphase separation from a completely disordered state in the melt to a specifically defined ordered structure through self-organization makes the block copolymers based materials unique. Block copolymer are strongly replacing many of the commercially available polymers due to their unique microstructure and properties. The most practical interests of block copolymers lie in the area of thermoplastic elastomers (TPEs). The objective of the present thesis work is to developing novel roots for enhancing the physical and mechanical properties in block copolymer and multigraft copolymers. Initially the properties are tailored by controlling chemical architecture at synthesis level and by selective blending at production level. This gives an easy access for improvement of the material properties and this is one of my major tasks in the present research modules.
Further the block copolymer based TPEs are cross-linked in presence of electron beam (EB) radiation for developing materials with superior properties. The electron beam radiation has the ability to alter material parameters at molecular level for enhancing the macroscopic properties. The desirable physical and chemical properties can be easily attained by varying the radiation beam parameters. In addition to that, controlling the material at nanometer scale is one of the greatest challenges for current nanocomposite research. In elastomeric materials it is very prominent to fill the rubber matrix with nano particles from carbon or silica by melt mixing technique for enhancing the material properties. Other than conventional melt mixing technique, sol–gel processing is also a versatile technique, which making it possible to produce a wide variety of materials and to provide existing materials with novel properties. A combination of in situ sol-gel reaction with electron beam cross-linking in TPEs from triblock copolymer has been demonstrated for the first time as one of the novel nanocomposite system in this work. The main advantage of this system lies in controlling the material behaviour by finely tuning the size of silica nano particle generated inside TPE during in situ sol-gel reaction. Finally, the various roots employed for enhancing the material behaviour in block copolymers in the above research module were secussfully employed on super elastic multigraft copolymers for improving their strength withour sacrificing the super elastic nature.
3
Tsartolia, E. "Graft copolymers." Thesis, University of Sussex, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381632.
Full text
4
Coetzee, Liezel. "Adamantane copolymers." Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52075.
Full textAbstract:
Thesis (PhD)--Stellenbosch University, 2001.ENGLISH ABSTRACT: This study concerns the incorporation of adamantane containing monomers 3-(1-adamantyl)-1-propene and 1-(1-adamantyl)-4-vinylbenzene into ethene, propene and higher a-olefins using different catalytic systems. The effect of the incorporation of the adamantane monomer on the physical and thermal properties of the polymers was investigated. A thorough study on the background of adamantane in general, as well as polymerization reactions involving the above-mentioned monomers and a-olefins was done. 3-(1-Adamantyl)-1-propene as well as 1,.(1-adamantyl)-4-vinylbenzene was sucessfully synthesized. The homo polymers of each monomer were made. The above-mentioned monomers were also polymerized: • . 3-( 1-adamantyl)-1-propene with ethene, propene and higher a-olefins, • 1-(1-adamantyl)-4-vinylbenzene with ethene and styrene. The copolymers of 3-(1-adamantyl)-propene as well as 1-(1-adamantyl)- 4-vinylbenzene were characterized as far as possible to show the influence of the incorporation of the adamantane group on the physical and chemical properties of the polymers. A series of 3-phenyl-1-propene copolymers with higher a-olefins were synthesized to compare the influence of the phenyl group to the adamantyl group on the relevant properties of the polymers.
AFRIKAANSE OPSOMMING: Hierdie studie behels die inkorporasie van adamantaan-bevattende monomere, 3-( 1-adamantiel)-1-propeen en 1-(1-adamantiel)-4-vinielbenseen in eteen, propeen en hoër a-olefiene met behulp van verskillende katalitiese sisteme. Die effek wat die inkorporasie van die adamantaan monomeer op die fisiese en chemiese eienskappe van die polimere het, is ondersoek. 'n Deeglike studie van die agtergrond van adamantaan in die geheel, sowel as die polimerisasie reaksies van die bogenoemde monomere met a-olefiene, is gedoen. 3-( 1-Adamantiel)-1-propeen sowel as 1-(1-adamantiel)-4-vinielbenseen is suksesvol berei. Die homopolimere van bogenoemde monomere is gesintetiseer. Bogenoemde monomere is gepolimeriseer: • 3-(1-adamantiel)-1-propeen met eteen, propeen en hoër a-olefiene, • 1-(1-adamantiel)-4-vinielbenseen met eteen en stireen. Die kopolimere van 3-(1-adamantiel)-1-propeen en 1-(1-adamantiel)- 4-vinielbenseen is sover moontlik gekarakteriseer om die invloed van die adamantaan groep op die fisiese en chemiese eienskappe van die polimeer te toon. 'n Reeks kopolimere van 3-(1-feniel)-1-propeen met hoër a-olefiene is gesintetiseer om die verwantskap tussen die invloed van die fenielgroep en die adamantielgroep op die relevante eienskappe van die polimere te toon.
5
Farias, Mancilla Bárbara Isabel. "Asymmetric copolymers : neither block nor random." Thesis, Toulouse 3, 2020. http://www.theses.fr/2020TOU30288.
Full textAbstract:
Les monomères d'un copolymère statistique sont aléatoirement mélangés, tandis que ceux d'un copolymère à bloc sont nettement séparés en sections de compositions différentes. Entre ces deux structures modèles existent des copolymères asymétriques, qui sont définis comme une distribution de monomères au sein de la chaîne qui n'est ni complètement ségrégée comme pour un copolymère à bloc ni statistiquement distribuée de manière indépendante de la position au long de la chaîne comme dans le cas des copolymères statistiques. Ainsi, les propriétés des copolymères asymétriques devraient combiner les caractéristiques des structures à bloc et statistiques. Dans cette étude, des copolymères d'acide acrylique-(acrylate de n-butyle) (AA-n-BA) et diméthylacrylamide-N-isopropylacrylamide (DMA-NIPAM), avec des masses molaires ciblés de 10 kg mol-1 et 20 kg mol-1 , ont été obtenus par polymérisation RAFT en utilisant une synthèse forcée et par étapes. Les deux systèmes de copolymères sont des polymères sensibles aux stimuli : des macromolécules qui subissent des transitions de phase lorsqu'elles subissent de subtils changements des conditions environnementales. Les copolymères P(AA-n-BA) réagissent au pH et les copolymères P(DMA-NIPAM) sont thermosensibles. Lors de cette étude, la composition des copolymères a été fixée (50% AA ou 50% NIPAM), mais la distribution des unités de monomères au sein de la chaîne varie. En effet, des structures à blocs, statistiques, à gradient, asymétriques dibloc et tribloc ont été obtenues dans le but de comparer leurs propriétés physiques et d'auto-assemblage. Les caractéristiques macromoléculaires des copolymères ont été obtenues par spectroscopie de résonance magnétique nucléaire (1H RMN) et chromatographie d'exclusion stérique (SEC). Les copolymères P(AA-n-BA) en solution à différents pH ont été étudiés par diffusion dynamique de la lumière (DLS), microscopie électronique à transmission cryogénique (cryo-TEM) et diffusion de neutrons aux petits angles (SANS) et il a été possible de démontrer les changements de taille et de comportement d'auto-assemblage en fonction du pH des différentes solutions de copolymères. Les résultats ont montré que les copolymères asymétriques P(AA-n-BA) forment des agrégats de morphologie différente selon le pH, par exemple des vésicules à pH 4 ou des micelles et des micelles vermiculaires à pH 5. D'autre part, la morphologie des copolymères à bloc de même composition, n'est pas influencée par les changements de pH. Les copolymères de P(DMA-NIPAM) ont été analysés en solution par DLS, SANS et 1H RMN en fonction de la température. L'évolution de la taille hydrodynamique en fonction de la température a pu être suivie par DLS. La micellisation induite par le changement de température a été analysée par SANS. Enfin, l'effondrement de la structure induit par la température et la perte de mobilité résultante des chaînes polymères ont été suivis à un niveau moléculaire par 1H RMN. Des résultats intéressants ont été obtenus, car les copolymères à bloc de faible masse molaire (Mn = 10 kg mol-1) présentent un comportement similaire au copolymère à gradient de masse molaire plus élevé (Mn = 20 kg mol-1). Ce phénomène a été observé par SANS et 1H RMN, et il a été attribué à la faible longueur du copolymère à bloc : une fraction significative des unités NIPAM dans le copolymère à bloc peuvent être en contact avec le DMA du bloc adjacent, conduisant à un changement progressif de la composition effective du polymère en fonction de la longueur de la chaîneBlock copolymers are made from polymer chains of different chemical composition that are covalently joined via their respective end groups. On the other hand, there are statistical copolymers whose monomers are randomly copolymerized together. Between these structures exist asymmetric copolymers, which are defined as a distribution of monomers within the chain which is neither completely segregated as for a block copolymer nor statistically distributed in a manner that is independent of the position along the chain as in the case of statistical copolymers. Based on the latter, the properties of asymmetric copolymers are expected to combine characteristics of block and statistical structures. In this investigation, acrylic acid-(n-butyl acrylate) (AA-n-BA) copolymers and dimethylacrylamide-N-isopropylacrylamide (DMA-NIPAM) copolymers, with targeted molecular weights of 10 kg mol-1 and 20 kg mol-1, were obtained by RAFT polymerization using forced and stepwise synthesis. Both copolymer systems are stimuli-responsive polymers: macromolecules which undergo phase transitions when they experience subtle changes in the environmental conditions. P(AA-n-BA) copolymers are pH-responsive and P(DMA-NIPAM) copolymers are thermosensitive. The composition of the copolymers was always the same (50% AA or 50% NIPAM), but the distribution of the monomer units within the chain was different. Block, statistical, gradient, asymmetric diblock and triblock structures were obtained with the aim to compare their physical and self-assembly properties. The macromolecular characteristics of copolymers were obtained by nuclear magnetic resonance spectroscopy (1H NMR) and size exclusion chromatography (SEC). P(AA-nBA) copolymers in solution at different pH were studied by dynamic light scattering (DLS), cryogenic transmission electron microscopy (cryo-TEM) and small angle neutron scattering (SANS) and it was possible to demonstrate the changes in size and self-assembly behavior as a function of pH of the copolymers solutions. The results showed that the P(AA-nBA) asymmetric copolymers form aggregates of different morphology depending on the pH, for example vesicles at pH 4 or micelles and worms at pH 5. On the other hand, the morphology of block copolymers with the same composition, is not influenced by changes in pH. P(DMA-NIPAM) copolymers in solutions were analyzed by DLS, SANS and 1H NMR as a function of temperature. The evolution of hydrodynamic size as a function of temperature could be followed by DLS and the temperature-induced micellization was analyzed by SANS whereas by 1H NMR, the temperature-induced collapse and resulting loss of mobility of the polymer chains could be followed at a molecular level. Interesting results were obtained, since low molar mass block copolymers (Mn = 10 kg mol-1) displayed similar behavior to the corresponding to high molar mass gradient copolymer (Mn = 20 kg mol-1). This phenomenon was observed by SANS and 1H NMR, and it was attributed to the short length scale of the block copolymer, in which the chain is short enough that a significant fraction of the NIPAM units in the block copolymer are strongly affected by the DMA of the adjoining block, leading to a gradual change in the effective composition of the polymer as a function of chain length
6
Wheatley, G. W. "Polyaryletherketone block copolymers." Thesis, University of Lincoln, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383989.
Full text
7
Kay, Christopher James. "Polyethylene block copolymers." Thesis, University of Warwick, 2014. http://wrap.warwick.ac.uk/62620/.
Full textAbstract:
Chapter 1 introduces the concept of polyethylene (PE) end-functionalisation as a route to block copolymers, reviews the different literature methods for their synthesis this way, and compares the advantages and disadvantages of each. Finally, an existing method which makes use of PE terminated with a styrene derivative is identified as having fewer disadvantages than most literature procedures. Further investigation of the mechanism is proposed. Chapter 2 focusses on the different types of so-called dormant state formed in Ziegler-Natta catalysed olefin polymerisations, and in particular on the dormancy occurring after styrene insertion. Copolymerisations of ethylene with styrene, allylbenzene and 4-phenyl-1-butene in the presence of hydrogen are undertaken, and evidence for the presence of a dormant state or simply competitive rates of hydrogenation vs ethylene insertion is discussed. Increasing styrene concentration beyond that used by Chung is found to yield PE capped at both chain ends with styrene. A new mechanism – Catalytic Hydride Initiated Polymerisation (CHIP) – is consistent with these new observations. Chapter 3 focusses on extending the application of the CHIP mechanism to the synthesis of new examples of end-functional PE. Copolymerisations of ethylene with α-methylstyrene and related monomers 1,3/1,4-diisopropenylbenzene, α-methylstyrene dimer and limonene in the presence of hydrogen are investigated, resulting in the successful synthesis of a range of PE examples initiated with each comonomer. The effects of hydrogen pressure and comonomer concentration are also discussed. The advantages of CHIP are discussed, and the synthesis of end-functionalised PE incorporating DIB is studied in detail. An α-methylstyrene like end group is present at the start of the PE chains. Chapter 4 describes the free-radical copolymerisation of the new functionalised PE with acrylate monomers. Observations are consistent with a new reversible termination mechanism similar to nitroxide mediated polymerisation. The products are characterised by NMR, GPC, DLS, TEM and DSC, and the evidence is found to be consistent with the presence of block copolymers. Chapter 5 details the experimental procedures used to carry out the work in this thesis.
8
Elmaci, Aysegul. "Thermal Characterization Of Homopolymers, Copolymers And Metal Functional Copolymers Of Vinylpyridines." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609892/index.pdf.
Full textAbstract:
Although, the use of vinyl pyridine polymers, especially as matrices for
nanoparticle synthesis, is growing considerably, the knowledge of thermal
degradation behavior is still missing in the literature. In this study, thermal
degradation characteristics of the homopolymerspoly(4-vinylpyridine), P4VP, and poly(2-vinylpyridine), P2VP, the diblock copolymers
polystyrene-blockpoly( 2-vinylpyridine), (PS-b-P2VP) and polystyrene-block-poly(4-vinylpyridine), (PS-b-P4VP), and the metal functional vinyl polymers
cobalt-polystyrene-blockpoly( 2-vinylpyridine) and cobalt-polystyrene-block-poly(4-vinylpyridine) were investigated by direct pyrolysis mass spectrometry. The effects of the position of the nitrogen in the pyridine ring, composition and molecular weight of diblock copolymer and coordination of the metal to the pyridine ring of the copolymer on thermal behavior were also investigated. The results showed that unlike most of the vinyl polymers that decompose via depolymerization, P2VP degrades through opposing reaction pathways
depolymerization, proton transfer to N atom in the pyridine ring yielding unsaturated linkages on the polymer backbone that decompose slightly at higher temperatures and loss of pyridine units. On the other hand the thermally less stable P4VP decomposition follows v depolymerization in accordance to general expectations. Another finding was the independent decomposition of both components of the diblock polymers, (PS-b- P2VP) and (PS-b-P4VP). Thermal degradation occurs in two main steps, the thermally less stable P2VP or P4VP chains degrade in the first step and in the second step decomposition of PS takes place. It was also concluded that upon coordination of metal, thermal stability of both P2VP and P4VP increases significantly. For metal functional diblock copolymers thermal degradation of chains coordinated to Co metal through N in the pyridine ring occurred in three steps
cleavage of pyridine coordinated to Co, coupling and H-transfer reactions yielding unsaturated and/or crosslinked structure and decomposition of these thermally more stable unsaturated and/or crosslinked blocks. TEM imaging of the metal functional block copolymers along with the results of the pyrolysis mass spectrometry pointed out that PS-b-P2VP polymer is a better and more effective matrix for nanoparticle synthesis.
9
Nguyen, Duc Anh. "Cycloalkenyl macromonomers from new multifunctional inimers : a platform for graft, bottle-brush and mikto-arm star copolymers." Thesis, Le Mans, 2016. http://www.theses.fr/2016LEMA1001/document.
Full textAbstract:
Le sujet de cette thèse concerne l'élaboration de macromonomères, de copolymères greffés et de polymères étoiles de type 'mikto-arm'. De telles architectures macromoléculaires ont été synthétisées par la combinaison de techniques de polymérisation contrôlées/vivantes telles que la polymérisation par ouverture de cycle (par métathèse) (RO(M)P) etde chimie 'click' orthogonales : cycloaddition 1,3-dipolaireazoturealcyne catalysée au cuivre (CuAAC) et thiol-ène.Dans un premier temps, des macromonomères originaux à fonctionnalité polymérisable (oxa)norbornène portant deux chaînes macromoléculaires poly(e-caprolactone) (PCL) et/ou poly(oxyde d'éthylène) (POE) ont été synthétisés par combinaison ROP/CuAAC. Les macromonomères à fonctionnalité (oxa)norbornène avec deux chaînes PCL de masse molaire moyenne en nombre (Mn) compris entre 1400 et 5000 g/mol ont été obtenus par ROP organocatalysée. La synthèse des macromonomères POE44-b-PCLn à fonctionnalité norbornène avec un bloc PCL de longueur variable (1100 g/mol The objective of the present thesis was the preparation of complex macromolecules by the combination of controlled/livingpolymerization methods such as ring-opening (metathesis) polymerization (RO(M)P) and highly efficient orthogonal chemistries: copper-catalyzed azide-alkyne coupling (CuAAC) and thiol-ene reactions.In the first part of this work, a series of well-defined structural (co)polymers containing a cycloolefin (norbornene (NB) oroxanorbornene (ONB)) functionality bearing two polymer chains including poly(ε-caprolactone) (PCL) and/or poly(ethylene oxide) (PEO) have been successfully prepared using the combination of ring-opening polymerization (ROP) and CuAAC ‘click’ chemistry. Well-defined (oxa)norbornenyl-functionalized bis-PCL polymers with PCL chain ranging from 1400 to 5000 g/mol were obtained by organocatalyst-mediated ROP. Norbornenyl-functionalized PEO-b-PCL block copolymers with PCL block in the range 1100 to 4100 g/mol were synthesized from commercially available PEO 2000 g/mol by CuAAC followed by ROP of CL. The presence of a hydrophilic PEO chain and a hydrophobic PCL chain in norbornenylfunctionalizedPEO-b-PCL copolymers gives rise to self-assembling properties in water solution. Critical micellar concentrations (CMC)are in the range of 0.08 – 0.006 g/L for copolymers with PCL chain length ranging from 10 to 36 CL units, respectively. Thecorresponding micelles show hydrodynamic diameters in range of 10 – 23 nm with low polydispersities.In the second part of this work, well-defined copolymers were used to prepare bottle-brush and (mikto-arm) star copolymersthrough reactions involving the cycloolefin functionality. On the one hand, high density grafting bottle-brush copolymerspoly(oxa)norbornene-g-bisPCL, polynorbornene-g-PEO/PCL (PNB-g-(PEO/PCL)) and PNB-b-(PNB-g-(PEO/PCL)) were achieved by ROMP according to the ‘grafting through’ strategy using Grubbs’ catalysts. On the other hand, PCL, PEO, PNIPAM-based 3-arms star, 4-arms star copolymers were obtained via radical thiol-ene reactions as demonstrated by 1H NMR, SEC and MALDI-ToF MS analysis.The high reactivity of these copolymers toward ROMP and thiol-ene reactions makes them interesting candidates in order toprepare new well-defined copolymers with controlled structures and properties through highly efficient synthetic strategies
10
Ott, Marcell. "Nanostructuring with diblock copolymers." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=982533284.
Full text
11
Fleet, Reda. "RAFT mediated polysaccharide copolymers." Thesis, Link to the online version, 2006. http://hdl.handle.net/10019/1025.
Full text
12
Auden, Noel Geraint. "Ethylene-vinyl acetate copolymers." Thesis, Lancaster University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239046.
Full text
13
Holohan, Aidan. "Polyhydroxyether-polydimethylsiloxane graft copolymers." Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/46823.
Full text
14
Cho, Hansohl. "Mechanics of elastomeric copolymers." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/87972.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references.
Elastomeric copolymers have been versatile materials for a broad variety of engineering applications of critical importance ranging from ballistic protective coatings to self-healing microstructures, possessing a backbone structure composed of alternate hard and soft segments, where the hard/soft nomenclature corresponds to the thermodynamic glassy/rubbery state at ambient temperature. The thermodynamic incompatibility of microstructures often lead to a phase-separated morphology of the hard and soft domains which can be tailored depending on the chemical composition, molecular dispersion, processing and synthesis to give a variety of physical properties. The mechanical behavior of elastomeric copolymers is hence governed by the chemical composition as well as the morphology providing a hybrid performance by virtue of simultaneous contributions from constituent homopolymers often offering new and unique properties. In this research, the mechanics and physics of large deformation behavior of elastomeric copolymers are addressed in terms of their resilience and dissipation involving elastomeric "segmented" copolymers and elastomeric "ionic" copolymers. The presence of hard and soft domains yields to multiple molecular relaxations and hence multiple viscous dissipation mechanisms in elastomeric copolymers. In addition to the viscous dissipation, stretch-induced softening due to microstructural evolution revealed via x-ray scattering observation during deformation provides another major dissipation pathway. Furthermore the segmented copolymers exhibit a substantial shape recovery upon unloading in tandem with a remarkable amount of hysteresis. A microstructurally-informed constitutive model is proposed to address the main features of mechanical behavior of exemplar copolymers under a variety of loading conditions, employing multiple micro-rheological mechanisms representing hard and soft domains. The proposed model was found to be capable of capturing the salient features of resilient yet dissipative stress-strain behavior of materials at a wide range of strains and strain rates. The model was then furthered to examine the effect of weight fraction, morphology and segmental dynamics of hard and soft microstructures. Next, the resilience and dissipation in elastomeric segmented copolymers are examined in their connections to shape recovery under microindentation testing in experiments and numerical simulations. Numerical simulations imparting the proposed constitutive model were found to be capable of capturing the microindentation behavior of materials including force-displacement capable of capturing the microindentation behavior of materials including force-displacement responses under complicated loading scenarios. Additionally, the microindentation behavior revealed a substantial shape recovery of indented surfaces which was due to inelastic flow beyond elastic resilience. The elastically- and inelastically-driven shape recovery provides critical insight into a better understanding of shape memory, recovery and self-healing mechanisms in this class of segmented elastomers. The extreme nature of elastomeric copolymers under harsh mechanical environments is then addressed via Taylor impact testing, where an ultrafast deformation event is incurred. Numerical simulations of Taylor impact behavior of elastomeric copolymers are compared to experimental results in terms of overall and localized deformation profiles, revealing a three-dimensional capability of our framework under dynamic, inhomogeneous deformation field. Furthermore, energy dissipation under such an extreme event is examined by comparison to that found in "model" glassy and rubbery polymers revealing that copolymeric materials enable a highly recoverable, protective composite architecture for shock and ballistic mitigation by taking advantages of hybrid performance of glassy and rubbery polymers. Lastly, the mechanics of elastomeric "ionic" copolymers is addressed for a broad understanding of their resilience, dissipation and shape recovery under a wide range of mechanical loading conditions. Our viscoelastic-viscoplastic constitutive framework is further developed to address the large deformation behavior of ionic elastomers including ethylene methacrylic acid (EMAA) copolymer and its chemically-modified counterparts which are recently finding new avenues towards multi-functional soft materials involving their self-healing ability under severe deformation events. This study provides a simple yet intuitive framework to rationalize physically-sound deformation mechanisms of diverse elastomeric copolymers by employing a combination of novel modeling, experimentation and computation. Finally, potential topics for further research, to which the present work can directly contribute, are discussed in a wide variety of engineering contexts.
by Hansohl Cho.
Ph. D.
15
Taylor, William R. M. "Chromatographic characterisation of copolymers." Thesis, Loughborough University, 1997. https://dspace.lboro.ac.uk/2134/13601.
Full textAbstract:
Copolymers containing hydrophilic and hydrophobic segments find applications as polymeric surfactants in detergent formulations. The properties of such surfactants depend on molecular weight and composition of copolymer chains, and in particular on the heterogeneities in molecular weight distribution and chemical composition distribution within samples. Heterogeneity in copolymer composition may include the presence of a homopolymer which would not be active in a detergent application. In this thesis work is directed to the development of separation methods by reversed phase chromatography to characterise copolymers according to composition. Copolymer systems include acrylic acid/lauryl methacrylate, poly(ethylene oxide)lvinyl acetate, and polyesters based on terephthalic acid, poly( ethylene oxide) and glycerol. The outcome of these separations has been the isolation of poly acrylate and copolymer; poly(ethylene oxide), poly(vinyl acetate) and copolymer from their respective copolymer systems; and the separation of poly( ethylene oxide) and glycerol from the polyester samples. Spectroscopic analysis of the fractions for each copolymer enabled complete characterisation and quantification of the copolymers present.
16
Staisch, Ingrid. "Novel siloxane block copolymers." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/1303.
Full textAbstract:
Thesis (PhD (Chemistry and Polymer Science))--Stellenbosch University, 2008.The research presented in this dissertation was concerned with the living radical polymerization (LRP) of an amphiphilic, water-soluble, bi-substituted and biologically compatible acrylamide derivative, namely n-acryloylmorpholine (NAM). The primary objective of this research was the synthesis of novel block copolymers containing poly(dimethylsiloxane) (PDMS) and various chain lengths of poly(acryloylmorpholine) (polyNAM) using a LRP technique, namely reversibleaddition fragmentation chain transfer (RAFT) polymerization. This is the first report on the synthesis of these block copolymers using RAFT polymerization. These novel siloxane block copolymers were synthesized using a monohydroxyterminated PDMS material which had to first be modified into a thiocarbonylthiocontaining moiety in order for it to be used as macromolecular chain transfer agent (macroCTA) in the RAFT copolymerization with NAM. Suitable reaction conditions for the synthesis of these novel block copolymers had to, firstly, be determined, and secondly, optimized. In order to determine suitable reaction conditions, a series of homopolymerizations with NAM were first performed in order to compare which chain transfer agent (CTA), solvent, temperature etc. could possibly be best suited for the block copolymerizations of PDMS-b-polyNAM. Reported in this work is the first account of the homopolymerization of NAM and 2-(dodecylsulfanyl)thiocarbonylsulfanyl-2-methyl propionic acid (DMP) as CTA using RAFT polymerization. The resulting novel siloxane block copolymers are amphiphilic in nature and the existence of these structures was confirmed by size exclusion chromatography/multiangle light scattering (SEC/MALS), proton nuclear magnetic resonance (1H-NMR) spectroscopy, gel elution chromatography (GEC) and transmission electron microscopy (TEM). Interesting phase behaviour was observed in the latter technique.
17
Xiang, Yunjie. "Towards multifunctional supramolecular copolymers." Thesis, Strasbourg, 2014. http://www.theses.fr/2014STRAF015/document.
Full textAbstract:
Le but de cette thèse était de comprendre l'organisation supramoléculaire et le possible réarrangement dynamique de copolymères supramoléculaires multifonctionnels. Ainsi, nous avons synthétisé diverses molécules présentant un coeur urée ou pérylène fonctionalisé par différentes chaines latérales afin de combiner des propriétés de structuration, de fluorescence et de bioreconnaissance dans une même chaine de polymère supramoléculaire. En combinant différentes techniques de spectroscopie, de diffusion du rayonnement et de microscopie, nous avons montré que des molécules avec un même coeur mais des chaines latérales différentes conduisaient à des nanostructures différentes comme des rubans vrillés, des plaques 20 ou encore des fibres branchées. Enfin, plusieurs unités monomériques avec un même coeur mais des chaines latérales différentes ont été mélangées pour former des copolymères supramoléculaires multifonctionnels. La formation préférentielle d'une nanostructure unique dictée par un des monomères a été démontrée selon un mécanisme de tri dit social ( « social self-sorting » )The goal of this thesis was to understand the supramolecular organization and the possible dynamic rearrangement of multifunctional supramolecular copolymers. To this end, we havedeveloped a series of building blocks based on urea or perylene cores with various lateral side chains for combining structuring, fluorescence, and biorecognition properties in a singlesupramolecular polymer chain. Using a combination of spectroscopy, scattering, and microscopy techniques, we have shown that molecules with a same core but different lateral chains can lead to the formation of various nanostructures su ch as twisted ribbons, 20 plates, or branched fibers. Ultimately, by combining monomeric units with different functional side chains, multifunctional supramolecular copolymers have been obtained. Whereas radiation scattering and imaging techniques were used to demonstrate that one of the monomer can dictate the formation of a preferential nanostructure, optical spectroscopies revealed that the polymerization process of our systems indeed occurs via social self-sorting
18
Dobriyal, Priyanka. "Cylindrically confined diblock copolymers." Amherst, Mass. : University of Massachusetts Amherst, 2009. http://scholarworks.umass.edu/dissertations/AAI3359893/.
Full text
19
Dirany, Mohammed. "Films minces auto-organisés à base de copolymères à blocs de type PS-PLA." Thesis, Orléans, 2009. http://www.theses.fr/2009ORLE2048/document.
Full textAbstract:
Les films minces de copolymères à bloc PS-b-PLA peuvent servir de gabarits pour la fabrication de nano-objets sur une surface. Ce copolymère à bloc doit dans ce cas être organisé sous forme de cylindres de PLA orientés perpendiculairement et arrangés en hexagone dans une matrice de PS sur plusieurs micromètres. Le PLA extrait par hydrolyse conduit alors à un film mince poreux. Dans cette perspective, des films minces ont été préparés par spin-coating d’une solution d’un PS-PLA, de fraction volumique en PLA 0,35. Les analyses en AFM, MEB montrent que les films ainsi préparés présente un état métastable avec une structure nanoséparée avec des cylindres de PLA orientés perpendiculairement et arrangés en hexagone très localement. Il est nécessaire de réorganiser les films pour obtenir une organisation à longue distance. Les recuits thermiques sous vide s’avèrent peu efficace. L’exposition des films à des vapeurs de solvant (THF, acétone et chlorobenzène) entraîne la réorganisation des films. La nature du solvant, le temps d’exposition conditionnent la morphologie observée. Une étude détaillée de ces paramètres permet d’obtenir une organisation optimale pour les applications visées. Une irradiation UV permet d’immobiliser le film sur la surface rendant possible l’extraction du PLA par hydrolyse. Des films de PS à nanoporosité organisés sur plusieurs micromètres peuvent donc être produits. En parallèle, une stratégie de synthèse originale de copolymères diblocs PS-PLA fondée sur la combinaison d’ATRP et du ROP en utilisant le tribromoéthanol comme amorceur commercial a été essayé. Après purification des copolymères synthétisés sur une colonne de silice afin d’éliminer les homopolymères PLA, les différentes morphologies obtenues après dépôt par spin-coating ont été étudiées et des expositions à des vapeurs de solvants ont été réalisées afin d’améliorer l’ordre à grande échelle des films préparésBlock copolymers thin films (PS-PLA) can be used as templates to fabricate nano-objects on a surface. This block copolymer must be organized in the form of cylinders of PLA oriented perpendicularly and arranged in a hexagonal array in PS matrix over several micrometers. PLA extracted by hydrolysis leads to a porous thin film. In this perspective, thin films were prepared by spin-coating from a solution of PS-PLA, the PLA volume fraction was 0,35. Analysis by AFM, SEM showed that the films prepared after spin-coating has a metastable state with a nanoseparated structure with PLA cylinders oriented perpendicularly and arranged in hexagon very locally. It is necessary to reorganize the films to obtain a long range order. The thermal annealing have been shown to be ineffective. The exposition of films to solvent vapours (THF, acetone and chlorobenzene) improves the reorganization of block copolymers thin films. The solvent nature and exposure time determine the film morphology. With a detailed experimental study of these parameters we determine the experimental conditions to obtain thin films with cylinders of PLA oriented perpendicularly and arranged in hexagonal array over several micrometers (exposure to THF for 4H). UV irradiation immobilizes the film on the surface and therefore the extraction of PLA is possible by hydrolysis. Nanoporous polystyrene thin film organized over several micrometers can be produced. In parallel, original synthesis of PS-PLA based on the combination of ATRP and ROP using commercial dualinitiator tribromoethanol has been tried. After purification of copolymers synthesized on a silica column to remove the PLA homopolymer, the morphologies obtained after spin-coating have been studied and exposition to solvent vapours were performed to improve the film order-scale
20
York, Gregory A. "Structure-property relationships of multiphase copolymers." Diss., This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-07102007-142517/.
Full text
21
Morkel, C. E. "Synthesis and characterisation of amphiphilic block copolymers /." Link to the online version, 2005. http://hdl.handle.net/10019/1119.
Full text
22
Ding, Ke. "Architectures of DNA block copolymers." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=98214217X.
Full text
23
Weißbach, Thomas. "Blending of Proton Conducting Copolymers." Master's thesis, Universitätsbibliothek Chemnitz, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-61695.
Full textAbstract:
Highly proton conducting polymers for operation in hydrogen/oxygen proton exchange membrane fuel cells (PEMFCs) provide often a poor mechanical strength due to high water contents. To strengthen the conducting polymers, blends with different ratios of partially fluorinated sulfonic acid graft and diblock copolymers with perfluorinated polymers were prepared. To analyze the effect of the different quantities of the compounds, with regard to water sorption and proton conducting properties, membranes were prepared by dissolving the components and drop casting.
Partially sulfonated poly([vinylidene difluoride-co-chlorotrifluoroethylene]-g-styrene) (P(VDF-co-CTFE)-g-SPS) was blended with polyvinylidene difluoride (PVDF), decreasing the ion exchange capacity (IEC). The blended polymers absorbed less water. However, the by AC impedance spectroscopy determined proton conductivity stayed stable or increased slightly. The effective proton mobility remained constant. Partially sulfonated poly([vinylidene difluoride-co-hexafluoropropylene]-b-styrene) (P(VDF-co-HFP)-b-SPS) with two different PS-block lengths were blended with different amounts of poly(vinylidene difluoride-co-hexafluoropropylene) (P(VDF-co-HFP)). In that case, the polymers absorbed less water and the proton conductivity decreased stepwise by adding more than 20 wt% P(VDF-co-HFP). The results indicate that a blending of P(VDF-co-CTFE)-g-SPS with PVDF inhibits swelling without having an effect on the proton conductivity, though water sorption and IEC are reduced.
24
Parent, John Scott. "Catalytic hydrogenation of butadiene copolymers." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq21378.pdf.
Full text
25
Cooper, Kevin L. "Liquid crystalline multi-block copolymers." Diss., This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-05222007-091335/.
Full text
26
Cooney, D. T. P. "Nanoporous materials from block copolymers." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.597952.
Full textAbstract:
This project assesses the potential for block copolymers (BCPs) to be used in making nanoporous membranes. BCPs self assemble to produce structured phase morphologies based on their molecular composition. One such structure is composed of cylinders of one polymer phase in a matrix of another. It is proposed that nanoporous products could be produced by selectivity removing the material forming the cylindrical phase in an aligned BCP sample. Methods of inducing good phase alignment in BCP samples are reviewed. The effects of high shear rates on the orientation of a cylindrical phase formed by a triblock copolymer are investigated using the Cambridge Multipass Rheometer and a customised X-ray diffraction system. A new X-ray collection technique is developed and used to show that high shear rates can destroy phase orientation in a BCP melt. BCP etching is investigated. The removal of a cylindrical poly(lactide) phase in a P(S-b-LA) BCP by hydrolysis is examined. The method is shown to produce complete removal of the PLA phase, with the etch considered to be reaction limited. Diffusion of acid and alkali through such etched samples is observed in a specially designed cell. Transport in aqueous conditions is established through samples up to 7 mm long, proving pore continuity in the material and establishing the practical validity of the proposed idea. Thin films of BCP aligned using electric fields are obtained and etched. Acid transport through the films indicates porosity has been introduced. Size exclusion experiments using gold colloids prove that small particles are transmitted by these films, whilst large particles are retained. These experiments establish that size separation could be conducted using BCP products, as proposed, and form the basis for future work in developing such products.
27
Al-Samak, Basma. "Alternating ring-opened metathesis copolymers." Thesis, Queen's University Belfast, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343280.
Full text
28
Thompson, Jillian Margaret. "Olefin metathesis polymers and copolymers." Thesis, Queen's University Belfast, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314162.
Full text
29
Parker, James. "Graft copolymers of poly(methylphenylsilane)." Thesis, University of Kent, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274357.
Full text
30
Chisholm, M. S. "Copolymers containing polydimethylsiloxane graft chains." Thesis, University of Aberdeen, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374088.
Full text
31
Biggs, Simon Richard. "Block copolymers in microemulsion systems." Thesis, University of Bristol, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303769.
Full text
32
Barker, Phil. "Crystallization of hydroxybutyrate/hydroxyvalerate copolymers." Thesis, University of Bristol, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317156.
Full text
33
Wilson, D. "Polyurethane-polymethyl methacrylate graft copolymers." Thesis, Imperial College London, 1988. http://hdl.handle.net/10044/1/47306.
Full text
34
Chan, Vanessa Zee-Haye 1973. "Ceramic nanostructures for block copolymers." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/9132.
Full textAbstract:
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2000.Vita.
Includes bibliographical references (leaves 224-234).
The field of nanotechnology has received burgeoning interest in recent years as the characteristic dimensions for many applications (such as integrated circuits and magnetic storage media) become smaller and smaller. In this work, block copolymers are harnessed in order to produce both porous and relief nanostructures. The interest in using these materials is due to the unique morphologies that block copolymers form and the fact that these nanostructures do so by self assembly. With careful selection of the relative volume fraction and phases, nanostructures with highly ordered and complex pore structures with a vast range of different symmetries can be produced; structures that are not attainable by more conventional processing techniques such as lithography. In this thesis, we have produced porous and relief ceramic nanostructures from self-assembling (template free) block copolymer precursors using a one-step, room temperature technique. To accomplish this, a silicon containing block copolymer system was used where upon exposure to an oxidation process the material undergoes two steps 1) the selective removal of the hydrocarbon block and 2) the formation of a ceramic from the inorganic containing block, resulting in nanoporous and nanorelief ceramics. These structures have potential to be used at temperatures far above the T 8 of traditional nanoporous or nanorelief polymers. By choosing the appropriate morphologies and parent block copolymers, 30 nanostructured ceramics with interfacial areas of-40 m2/g, masks for one-step lithography with a density of-5 x 1011 dots/cm2 or templates for the next generation of nanomagnets can be produced. In addition to these applications, it is envisioned that these structures can be used as photonic band gap materials, high temperature membranes and low dielectric constant materials. Specifically, the formation of both nanoporous and nanorelief structures from an ABA triblock copolymer system of poly(pentamethyldisilylstyrene) P(PMDSS) with polyisoprene was studied. The focus of this thesis is on the oxidation of the double gyroid and ''inverse" double gyroid morphologies using either ozone/uv and oxygen plasma techniques. By transmission electron microscopy (TEM) and atomic force microscopy (AFM), it is shown that the PI can be preferentially removed by oxidation resulting in a nanoporous material in the case of the double gyroid morphology and a nanorelief material in the case of the inverse double gyroid morphology. Oxidation of the P(PMDSS) homopolymer was also studied chemically using X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), Fourier Transform Infra-red Spectroscopy (FTIR), Rutherford Backscattering Spectrometry (RBS) and Forward recoil Spectrometry (FRES) and morphologically by AFM. Through these chemical analysis techniques, it is demonstrated that the ozone + uv and uv only oxidation processes converts thin films of P(PMDSS) to a ceramic, specifically silicon oxycarbide, that is far more stable than the parent homopolymer.
by Vanessa Zee-Haye Chan.
Ph.D.
35
Rychkov, Igor. "Block copolymers under shear flow." 京都大学 (Kyoto University), 2004. http://hdl.handle.net/2433/145457.
Full textAbstract:
Kyoto University (京都大学)0048
新制・課程博士
博士(理学)
甲第11046号
理博第2824号
新制||理||1421(附属図書館)
22578
UT51-2004-J718
京都大学大学院理学研究科物理学・宇宙物理学専攻
(主査)教授 吉川 研一, 教授 小貫 明, 助教授 瀬戸 秀紀
学位規則第4条第1項該当
36
Pegg, Jonathan Charles. "Colloidal properties of random copolymers." Thesis, University of Bristol, 2017. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.738265.
Full text
37
SIDARI, DIEGO. "Cyclolefin copolymers via chain shuttling." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2015. http://hdl.handle.net/10281/77608.
Full textAbstract:
L’introduzione di co- e ter-monomeri nella catena di polietilene, ottenuta con catalizzatori Ziegler-Natta permette di modularne le proprietà fisiche e chimiche come la temperatura di transizione vetrosa (Tg) e di incrementare le proprietà meccaniche e termiche del materiale.
In particolare, i copolimeri etilene-norbornene (E-N) ottenuti per sintesi metallocenica hanno alta resistenza termica, elevata resistenza all’azione di solventi, elevate proprietà barriera ai gas e alta trasparenza ottica (I. Tritto, L. Boggioni, D.R. Ferro, Coordination Chemistry Reviews, 250, 212-241, (2006)). Copolimeri ad alto contenuto di norbornene mantengono queste ottime caratteristiche ma sviluppano una componente fragile. Per sopperire a questo svantaggio, si è deciso di esplorare una nuova strategia di sintesi, introdotta nel 2006 dalla Dow Chemical Company (D.J. Arriola, E.M. Carnahan, P.D. Hustad, R.L. Kuhlman, T.T. Wenzel, Science, 312, 714 (2006)), chiamata “Chain Shuttling polymerization” (CSP). CSP permette di ottenere copolimeri con microstruttura multiblocco in cui differenti microstrutture sono legate insieme in una sequenza alternata all’interno della stessa catena polimerica. Il sistema catalitico della CSP è composto da tre componenti fondamentali: due catalizzatori con differente affinità alle unità monomeriche e un trasferitore di catena (CTA) che scambia le catene crescenti da un centro catalitico ad un altro.
A questo proposito abbiamo selezionato: i) un catalizzatore con alta affinità al norbornene, ii) un catalizzatore con bassa incorporazione di norbornene, iii) dietilzinco come agente di chain shuttling (CSA) e studiato due diversi sistemi catalitici: i) due zirconoceni con differenti leganti, per valutare l'influenza del legante sulle proprietà finali del polimero; ii) due metalloceni con diverso metallo centrale e gli stessi leganti. L'attivazione del catalizzatore è stata effettuata con dimetilanilinio tetrakis(pentafluorofenil)borato per entrambi i sistemi (M. Bochmann, Organometallics, 29, 4711-4770 (2010)).
Tutte le sintesi sono state eseguite in autoclave ad alta pressione (4-19 bar) a diversi rapporti molari N/E pari a 1.3,4.8 e 26.0. Tutti i copolimeri E-N sono stati caratterizzati con 1H e 13C NMR, cromatografia di esclusione (GPC) e analisi termica DSC.
Un primo screening è stato effettuato per identificare le migliori condizioni di copolimerizzazione per mantenere la conversione di N inferiore al 15%. Successivamente sono state eseguite sintesi di copolimeri E-N con un singolo metallocene in presenza di dietilzinco a tre diverse concentrazioni di Zn in soluzione per valutare effetto del CSA sulle proprietà finali dei copolimeri. Infine, è stata sintetizzata una serie di copolimeri E-N via CSP con entrambi i sistemi catalitici in presenza di dietilzinco.
L'analisi termica dei copolimeri E-N ottenuti tramite CS ha mostrato per tutti i copolimeri un unico evento Tg con valori intermedi tra quelli dei copolimeri ottenuti senza CSA. Inoltre le Tg non sono influenzate dalla concentrazione di Zn in soluzione. Viceversa, i pesi molecolari dei copolimeri E-N ottenuti tramite CS diminuiscono all’aumentare della concentrazione di dietilzinco in soluzione per tutti i catalizzatori selezionati. Sono state ottenute strette distribuzioni dei pesi molecolari (PDI=1,9 – 2,2) mentre i prodotti delle reazioni di terminazione sono presenti in quantità trascurabile. Queste caratteristiche ci permettono di concludere che la polimerizzazione procede tramite il meccanismo CS ed è quindi possibile ottenere copolimeri E-N con struttura multiblocco.
38
Smith, Susan Abenes. "Synthesis and characterization of perfectly alternating segmented copolymers comprised of poly(dimethylsiloxane)s and engineering thermoplastics." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-03022010-020156/.
Full text
39
Colin, Charlotte. "Synthèse et caractérisation de copolymères Silicone/Polyuréthane réticulés pour l'encapsulation de modules de puissance." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLV028/document.
Full textAbstract:
L’électronique embarquée, notamment les modules de puissance, permet la gestion de l’énergie électrique et donc le développement de véhicules « décarbonés ». Toutefois, en vue d’être positionnés près du moteur thermique, ces composants électroniques devront résister à des environnements très divers et parfois à de sévères contraintes (humidité, agression chimique (huiles), vibrations…). Or, les matériaux d’encapsulation qui les protègent ne sont pas, aujourd’hui, assez performants pour répondre à ces nouvelles contraintes. Ainsi, le but de ces travaux de thèse est donc de développer de nouveaux polymères d’encapsulation. Pour cela, deux types de copolymères Silicone/Polyuréthane (Si/PU) réticulés ont été synthétisés, sans solvant, et avec des temps de polymérisation courts.Une première série de matériaux Si/PU contenant entre 55 et 76%m de motif silicone, a été synthétisée par polyaddition alcool-isocyanate à partir de précurseurs silicone, synthétisés ou commerciaux, et d’un pluriisocyanate, en présence d’un catalyseur. Une seconde série de copolymères Silicone/Polyhydroxyuréthane (Si/PHU) contenant 26 et 61%m de motif silicone a été obtenue sans isocyanate et sans catalyseur, à partir de poly(diméthylsiloxane) biscyclocarbonate et d’une triamine.Les propriétés mécaniques, thermiques et le caractère hydrophobe de tous ces matériaux ont été évalués. Dans le but d’améliorer les propriétés thermiques et de diminuer le coût de la résine d’encapsulation, des charges inorganiques ont été incorporées à certains polymères Si/PU.Les matériaux les plus intéressants ont été testés comme encapsulant dans des modules de puissance et les premières mesures électriques au cours de cyclages thermiques sont très prometteusesEmbedded electronics, particularly power modules, allows management of electric energy and therefore development of “carbon-free” vehicle. However, these electronic components, will shortly be located near heat engine automotive, and they must withstand various environments and sometimes, hard stresses (humidity, chemical aggression (oil), vibrations…). But actual encapsulation materials are not today efficient enough to match with these future imposed stresses. Thus, the aim of this work is to develop new encapsulation polymers. For this, two types of crosslinked Silicone/Polyurethane (Si/PU) copolymers were “solvent-free” synthesized and with short polymerization times.A first series of materials Si/PU containing between 55 and 76%wt silicone units were synthesized by alcool-iscyanate polyaddition from silicone precursor, synthesized or commercial, and a pluri-isocyanate, in the presence of catalyst. A second series of copolymers, Silicone/Polyhydroxyurethane (Si/PHU) containing 26 and 61%wt silicone units, was obtained without isocyanate or catalyst from poly(dimethylsiloxane) biscyclocarbonate and a triamine.Mechanical and thermal properties as well as hydrophobic character of all materials were evaluated. In order to improve thermal properties and decrease the cost of encapsulation resin, inorganic fillers were blended in some of Si/PU polymers.The most interesting materials were tested as encapsulant in power modules, and the first electrical measurements during thermal cyclings were very promising
40
Alakhras, Fadi. "Spectroelectrochemistry of Intrinsically Conducting Furan-Thiophenes Copolymers." Doctoral thesis, Universitätsbibliothek Chemnitz, 2008. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-200801350.
Full textAbstract:
Die elektrochemische Copolymerisation von Furan und Thiophen oder 3-Chlorothiophen wurde erfolgreich realisiert in einer Elektrolytlösung von Bortrifluorid-Diethylether + Ethylether (Verhältnis 1:2) bei konstantem Elektrodenpotenzial. Die Zugabe von Trifluoroessigsäure (TFA) (10 Vol-%) zu Bortrifluorid-Diethylether + Ethylether (Verhältnis 1:2) erniedrigte das Oxidationspotenzial der Monomere; die Polymerisationsgeschwindigkeit erhöhte sich, da TFA die Ionenleitfähigkeit des Elektrolyts vergrößert. Die Homopolymere zeigen nur einen Redoxpeak, verursacht durch Polymeroxidation und - reduktion. Die elektrochemische Copolymerisation wird bei verschiedenen Potenzialen und mit unterschiedlichen Thiophen- oder 3-Chlorothiophenkonzentrationen untersucht. Die Copolymere zeigen ein Redoxpeakpaar, dessen Position sich wesentlich von der der Homopolymere unterscheidet. Mit zunehmendem Polymerisationspotenzial und/oder zunehmender Konzentration an Thiophen- oder 3-Chlorothiophen werden auch mehr Thiophen- oder 3-Chlorothiopheneinheiten in den Copolymerfilm eingebaut. Ein Elektropolymerisationmechanismus wird für die Copolymere vermutet und die Copolymere weisen eine recht gute Langzeitstabilität der Redoxaktivität nach Zyklen in Acetonitril auf. In situ UV-Vis-Spektren der Homo- und Copolymerfilme wurden gemessen und λ1max, welches dem π → π*- Übergang entspricht, wurde bestimmt. Der optische Übergang bei λ2max vom Valenzband in das höhere Bipolaronband wurde ebenfalls bestimmt. Die Bandlücke für die Homo- und Copolymerfilme beim direkten Übergang wurde von der Kante im Absorptionsspektrum abgeschätzt. Die elektrochemische Thermodynamik für die Homo- und Copolymerfilme deutet darauf hin, dass jeweils ein Elektron von den Polymersegmenten, bestehend aus 4 Monomereinheiten, entfernt wird. Die untersuchten leitfähigen Filme zeigen einen Leitfähigkeitssprung mit einer stabilen Leitfähigkeit bis EAg/AgCl= 2 V. Diese Leitfähigkeitsänderung ist reversibel. Polyfuran hat verglichen mit Polythiophen eine geringere Leitfähigkeit und die Leitfähigkeit von Poly(3-chlorothiophen) ist rund eine Zehnerpotenz niedriger als die von Polythiophen. Da das in situ Leitfähigkeitsverhalten der Copolymere nicht die Summe der einzelnen Homopolymere bildet, kann man ausschließen, dass es sich bei den abgeschiedenen Copolymeren um Blockcopolymere handelt. Mit Hilfe der FTIR-Spektroskopie wurden Schwingungsspektren der Homo- und Copolymerfilme aufgenommen. Die Ergebnisse zeigen, dass es zur α-α'-Verknüpfung zwischen den Radikalkationen während der Copolymerisation kommt, was charakteristisch ist für α-substituierte fünfgliedrige heterozyklische Verbindungen. Der Mechanismus der elektrochemischen Degradation von Furan-Thiophen-Copolymeren wird ebenfalls mit Hilfe der gemessenen Spektren beschrieben. Die in situ Resonanz-Raman-Spektroskopie ergab, dass die spektroskopischen Eigenschaften der Copolymere zwischen denen der Homopolymere lagen. Bei höheren Polymerisationspotenzialen und höheren Konzentrationen an Thiophen oder 3-Chlorothiophen werden mehr Thiophen- oder 3- Chlorothiopheneinheiten in die Copolymerketten eingebaut. Es ist offensichtlich, dass die Ramanspektren der Copolymere wesentlich komplexer sind als die der Homopolymere, wodurch die Auswertung erschwert wird. Dennoch erinnern die Ramanspektren der Copolymere an die der Homopolymere. Die spektroelektrochemischen Eigenschaften der Copolymere haben bestätigt, dass deren Charakteristika zwischen denen der Homopolymere liegen, was deutlich macht, dass die Oxidation von Monomeren möglich ist und dass die Copolymerketten demnach aus Furan- und Thiophen- bzw. 3- Chlorothiopheneinheiten bestehen könnenElectrochemical copolymerization of furan and thiophene or 3-chlorothiophene was successfully realized in a solvent system consisting of boron trifluoride ethyl ether (BFEE) + ethyl ether (EE) (ratio 1:2) at constant electrode potential. The addition of trifluoroacetic acid (TFA) (10 % by volume) to BFEE + EE (ratio 1:2) decreased the oxidation potential of the monomers; the polymerization rate was also accelerated because TFA increases the ionic conductivity of the electrolyte. The homopolymers have only one redox peak caused by polymer oxidation and reduction. Electrochemical copolymerization both at different potentials and with different thiophene or 3-chlorothiophene concentrations is investigated. The copolymers show one anodic/cathodic peak couple that appears at a position quite different from the positions observed with homopolymers. More thiophene or 3-chlorothiophene units are incorporated into the copolymer film with an increasing polymerization potential of the copolymer and/or with an increasing concentration of thiophene or 3- chlorothiophene in the feed. An electropolymerization mechanism of copolymers has been proposed, and the copolymers show a fairly good long-term stability of the redox activity after cycling in acetonitrile. In situ UV-Vis spectra of the homo- and copolymer films were measured and λ1max which corresponds to the π → π* transition is determined. The optical transition with λ2max from the valence band into the higher bipolaron band is also assigned. The band gap (Eg) for homo- and copolymer films from a direct interband transition is estimated from the absorption edge of the spectrum. The redox thermodynamics of the homo- and copolymer films suggest that one electron is removed from polymer segments containing four monomer units. The studied conducting films show a single conductivity change with a stable conductivity up to EAg/AgCl= 2 V. The conductivity of these films is almost restored when the potential shift direction is reversed. Polyfuran compared to polythiophene, has a lower conductivity and the conductivity of poly(3-chlorothiophene) is around one order of magnitude lower than that of polythiophene. The in situ conductivity properties of the copolymers are not the sum of those of the individual homopolymers. This result may eliminate the possibility that the copolymers can be considered as block copolymers. Vibrational spectra of homo- and copolymer films investigated in this study have been obtained using FTIR spectroscopy. The results indicate that α-α' coupling of radical cations has taken place in the copolymerization. This is a characteristic of α-substituted five-membered heterocyclic compounds. The electrochemical degradation mechanism of furan-thiophene copolymers is also described using the obtained spectra. The in situ resonance Raman spectroscopy of the copolymers shows spectroscopic properties intermediate between those of homopolymers. At higher polymerization potentials and at higher concentrations of thiophene or 3-chlorothiophene in the feed more thiophene or 3-chlorothiophene units are incorporated into the copolymer chains. It is obvious that the Raman spectra of the copolymers are more complex than those of homopolymers, which makes the assignment difficult. However, the in situ Raman spectra of the copolymers are reminiscent of those of the homopolymers. The spectroelectrochemical properties of the copolymers confirmed that the copolymers show intermediate characteristics between the homopolymers, implying that oxidation of monomers is possible and the copolymer chains may accordingly be composed of furan and thiophene or 3-chlorothiophene units
41
Akoumeh, Rayane. "Films hiérarchiquement micro structurés en nid d’abeilles : élaboration, étude de la topographie et de la chimie de surface par TOF-SIMS." Thesis, Pau, 2016. http://www.theses.fr/2016PAUU3052/document.
Full textAbstract:
Dans le domaine des polymères, l'auto-organisation de la matière a été largement étudiée dans les dernières années et beaucoup de progrès dans le domaine des films ordonnés, générés par l'auto-assemblage de copolymères à blocs, ont été réalisés. Ce progrès est motivé par le fait que les films auto-assemblés possèdent des applications en biologie, photonique, adhésion. Le sujet initial de thèse est la fabrication des films structurés en nid d’abeilles formés par un bloc de copolymère contenant une partie hydrophobe ( à peu près 90%) et une partie hydrophile (10%) qui peuvent s’auto-organiser en nid d’abeilles. Les films de polymères préparés seront ultérieurement à la base d’une étude de complexation avec des métaux. Ceci sert à décontaminer les eaux usées des métaux ou pesticides. Durant ces années de thèse, une méthodologie d’analyse de surface est détaillée pour comprendre la topographie de ces films ainsi que la chimie de surface de ces derniers. Pour cette raison, divers techniques d’analyses sont utilisées pour décrire vigoureusement la surface de ces films afin d’optimiser ces films pour complexer les contaminants à origine industrielle.Une des techniques d’analyse de surface, i.e. TOF-SIMS (Time Of Flight-Secondary Ion Mass Spectroscopy), a prouvé être un outil efficace pour caractériser chimiquement la composition élémentaire et moléculaire de l’extrême surface et en profondeur. Cette technique était la technique de base de ces études. Elle la permis de décrire les empreintes spectrales ainsi que la distribution en surface et en profondeur de chaque polymère dans les films élaborés en nid d’abeillesSince its introduction in 1994, the preparation of ordered porous polymer films by the breath figure “BF” method has received a considerable interest. Self-organized porous polymer films, with pores ordered into a hexagonal pattern, can be elaborated by a fast solvent evaporation method under a humid atmosphere, also called “Breath Figure” approach. The honeycomb films have found a panel of perspective applications ranging from materials with optical properties, biomaterial sensors, and scaffold for tissue engineering or highly hydrophobic surfaces. The main objective of this PhD thesis project is the fabrication of sensitive hierarchically self-organized bio inspired films based on organic compound trapping block copolymers. It is worth noting that one of the advantages of using block copolymer structure is that the first block confers the hydrophobic character, required for the elaboration and stability of HC structure, and the second block could provide an additional functionality such as hydrophilicity, stimuli-responsive character or trapping of targeted molecules (especially metals).During this thesis, a methodology of surface analysis is performed in order to understand the topography of these films as well as its surface chemistry. For this reason, various analytical techniques are used to describe the surface of these films vigorously in order to optimize these films to complex industrial contaminants.One of the techniques of surface analysis, i.e. TOF-SIMS (Time of Flight-Secondary Ion Mass Spectroscopy), has proved to be an effective tool for chemical characterization of the surface and in depth. This technique was the basic technique of our studies. It allowed the description of spectral finger prints as well as the distribution on the surface and in depth of each polymer in the structured films
42
Alvarez, Fernández Alberto. "Hybridization of block copolymer thin films with plasmonic nanoresonators for optical metamaterials design." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0168/document.
Full textAbstract:
Le concept de metamatériaux est apparu au cours des années 2000 avec la réalisation de structures artificielles permettant une propagation non-conventionnelles des ondes électromagnétiques. La réponse électromagnétique des metamatériaux est liée à la présence d’éléments optiquement résonants, de dimensions inférieures aux longueurs d’onde d’excitation, arrangés dans une structure périodique prédéfinie.Afin de produire les structures géométriques inhérentes au design de metamatériaux, l’auto-assemblage des copolymères à blocs constitue une méthodologie émergente. En effet, les structures périodiques produites lors de la séparation de phase de ces matériaux peuvent être utilisées en tant que canevas pour la création de réseaux périodiques de nanoparticules. L’objectif principal de ces travaux de thèse a ainsi été de démontrer la validité de cette stratégie pour la réalisation, d’une manière simple et reproductible, d’une large gamme de nanostructures et de corréler les paramètres structuraux de ces réseaux de nanoparticules aux propriétés optiques.Une première démonstration de ce concept a été obtenue en utilisant un copolymère à blocs formant une structure lamellaire afin de réaliser des surfaces possédant des indices de réfraction élevés. La formation contrôlée de particules métalliques au sein de cette structure a permis de produire des surfaces décorées par ces nanoparticules, pour lesquelles une corrélation entre la teneur en or et l’indice de réfraction résultant a pu être établie. Ce concept a été poussé plus en avant en utilisant une gamme des copolymères à blocs de différentes masses molaires et formant une morphologie cylindrique. En effet, un contrôle accru des paramètres structuraux des réseaux de nanoparticules (diamètre et distance inter-particules) a permis la réalisation de metasurfaces aux propriétés optiques variées. Enfin la mise au point d’une stratégie d’auto-assemblage itérative nous a permis d’obtenir des metasurfaces au design complexe, avec notamment la production de surfaces décorées par des clusters bimétalliques ou des multicouches hybrides polymère/metal. Dans l’ensemble des cas, les surfaces décorées de nanoparticules ont été minutieusement caractérisées par des techniques de microscopie et de diffraction RX afin de mieux appréhender les propriétés optiques dérivées d’analyses d’ellipsométrie spectroscopique à angle variableThe concept of metamaterials appeared in the years 2000 with the achievement of artificial structures enabling nonconventional propagation of electromagnetic waves. The electromagnetic response of metamaterials is based on the presence of optically resonant elements of sub-wavelength size and well-designed morphology and organization.In order to create controlled geometrical structures inherent to metamaterials design, block copolymer self-assembly constitutes an emerging strategy. Indeed, the periodic structures inherent to their segregation behavior can be used as scaffolds to create various regular or ordered nanoparticles arrays. The main objectives of this study is to demonstrate that block copolymer can indeed lead to a high level of control of a variety of designed nanostructures, in an easy and scalable method, and to correlate the structural parameters of the nanoparticles arrays and their optical properties.As a first demonstration, a lamellar-forming (poly(styrene)-block-poly(2-vinylpyridine) was used to create high refractive index surfaces. The selective and customizable metal incorporation within the out-of-plane lamellae produces azimuthally isotropic metallic nanostructures of defined geometries, for which a clear relationship between the gold content and the refractive index was established. Further studies were dedicated to the correlation between the geometrical parameters of the nanoparticles arrays and the optical properties through the macromolecular engineering of a series of cylinder-forming block copolymers having a wide range of molecular weights. Through this strategy, the particle diameter and the inter-particle distance were tuned leading to the production of metasurfaces with various optical characteristics. More complex metasurface designs were also obtained using a layer-by-layer self-assembly strategy, i.e. bimetallic raspberry nanoclusters or layered hybrid (metallic/polymer) structures. In all cases, the nanoparticles arrays were thoroughly analyzed using microscopy and small-angle X-ray scattering techniques in order to better apprehend the optical properties derived from variable-angle spectroscopic ellipsometry analysis
43
Lassagne, Adrien. "Synthèse et caractérisation de nouveaux électrolytes copolymères pour batteries lithium métal polymère." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAI063.
Full textAbstract:
Ces travaux ont pour objet la synthèse et la caractérisation de nouveaux électrolytes polymères pour batterie lithium métal polymère (LMP). L’objectif principal de ces électrolytes est de combiner une conductivité ionique élevée jusqu’à basse température et une résistance efficace contre les dendrites de lithium. Pour y parvenir, trois catégories de copolymères à bloc ont été élaborés, ils permettent d’obtenir une synergie de propriétés à priori antagonistes au sein d’un même matériau. Premièrement, la rigidité du polystyrène (PS) a été combinée à la conductivité du polyoxyéthylène (POE) dopé avec un sel de lithium (LiTFSI). Le POE a été préalablement modifié pour en abaisser la température de fusion (Tf) initialement située à 60°C, ce qui permet d’atteindre de hautes conductivités (7.10-5 S.cm-1) à 40°C, associées à un module d’Young de 0,3 MPa. Cependant, les bonnes conductivités de ces matériaux ne sont assurées que par une petite fraction de Li+ (t+=0,15). Cela crée des gradients de concentration qui limitent les performances des batteries. Pour pallier cela, l’anion TFSI a été greffé sur le bloc PS (PSTFSI), augmentant le t+ à 1. Le bloc PSTFSI combiné à du POE modifié a permis des conductivités remarquables pour un électrolytes solide (10-6 S.cm-1 @ 40°C). Dans un second temps, l’ajout d’une chaine perfluorée entre le PS et l’anion a permis un gain supplémentaire de conductivité par rapport au PSTFSI (2.10-5 S.cm-1 @ 60°C), uniquement assurée par les Li+. Dans chacune des trois catégories d’électrolytes plusieurs compositions ont été synthétisées, nous permettant de suivre l’impact de cette composition sur les morphologies, les propriétés thermodynamique et mécanique ainsi que sur les propriétés de transport. Finalement, des batteries LMP de laboratoire ont été assemblées avec les meilleurs électrolytesThis work deals with synthesis and characterization of new polymer electrolytes for lithium metal polymer (LMP) batteries. The main challenge of polymer electrolytes is to combine both high ionic conductivity at low temperature and good mechanical properties. To overcome these issues, block copolymers have been designed. Remarkable properties are reached thanks to the self-assembly of these triblock copolymers. Mechanical properties are given by stiff polystyrene (PS) domains whereas ionic mobility operates in an ionophilic phase, polyoxyethylene (POE) with a lithium salt (LiTFSI). By introducing chemical defects in the POE backbone, melting temperature of the copolymer has been considerably lowered leading to conductivities of about 7.10-5 S.cm-1 and a Young’s modulus of 0.3 MPa at 40°C. If interesting properties are obtained thanks to this strategy, the small fraction of conductivity insured by lithium ions (t+=0.15) remains an issue. The low t+ leads to large concentration gradients limiting the performances of the system. In a second approach, TFSI anions have been covalently tethered on the PS backbone, raising the t+ to 1. An important increase of Li+ conductivity was obtained by adding a perfluorinated spacer between PS and TFSI moieties, with an ionophilic phase based on PEO (2.10-5 S.cm-1 @ 60°C). The chemical modification of the PEO block leads to Li+ conductivities of 10-6 S.cm-1 at 40°C. The composition of these different copolymers have been varied and their structural, thermal, mechanical and transport properties have been studied. Finally the best electrolytes of each category have been assessed in a full cell configuration
44
Pradhan, Swapna. "Ionic, water soluble polyfluorene type copolymers." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=974105406.
Full text
45
Higley, Mary Nell. "The Synthesis of Modular Block Copolymers." Thesis, Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14497.
Full textAbstract:
A novel methodology has been developed for the formation of block copolymers that combines ring-opening metathesis polymerization (ROMP) with functional chain-transfer agents (CTAs), functional chain-terminators (CTs) and self-assembly. Telechelic homopolymers of cyclooctene derivatives that are end-functionalized with hydrogen-bonding or metal-coordination sites are formed via the combination of ROMP with a corresponding functional CTA. These telechelic homopolymers are fashioned with a high control over molecular weight and without the need for post-polymerization procedures. The homopolymers undergo fast and efficient self-assembly with their complement homopolymer or small molecule analogues to form block copolymer architectures. The block copolymers have similar association constants to small molecule analogues described in the literature, regardless of size or the nature of the complementary unit or the polymer side-chain. The ROMP of side-chain functionalized norbornene polymers is coupled with functional CTs to produce block copolymer with main- and side-chain self-assembly sites. Combinations of these norbornene polymers with their complement polymer via self-assembly produce non-covalent AB type block copolymers fast and efficiently. ABA type block copolymers are realized by combining the difunctional homopolymer formed via the CTA pathway with the CT synthesized mono-functional polymer. These polymers show similar association constants regardless of the sequence of polymer formation.
46
Aran, Bengi. "Preparation Of High Performance Acrylonitrile Copolymers." Phd thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/3/12611334/index.pdf.
Full textAbstract:
Acrylonitrile based engineering random copolymers were prepared via one step emulsion polymerization using ammonium persulfate (initiator), 1-dodecanthiol (chain transfer agent) and DOWFAX 8390 (surfactant) in the presence of water at approximately 65 0C. Three copolymer compositions were studied for novel polyacrylonitrile, (PAN)-polyhydroxyethyl acrylate (PHEA), PAN-polybutyl acrylate (PBA), novel PAN-polyt-butyl acrylate (PtBA), PAN-polyethyl acrylate (PEA) and PAN-polymethyl acrylate (PMA) with acrylate content varying from 8, 12 and 16 molar percent. Infrared spectroscopy, proton and carbon NMR were successfully utilized to confirm the chemical structure of copolymers. In order to determine the comonomer compositions in the copolymer structure, proton nuclear magnetic resonance, 1H NMR studies were carried out. Thermal (TGA, DSC) and mechanical properties of homo and copolymers were also investigated. Intrinsic viscosity (IV) measurements in dimethyl formamide (DMF) solution revealed that the molecular weight of the copolymers were quite enough to form ductile films.
In this study, hydrogels and their copolymers of acrylonitrile (PAN-PHEA) were also studied. Some properties of the free standing copolymer films such asswelling behaviors and densities were evaluated. It was also demonstrated that the nanocomposites of these copolymers could be utilized in filtration technology. Hence, novel PAN(88)-co-PMA(12) and polyaniline (PANI) nanocomposites were prepared at various PANI loadings to remove toxic chromium(VI) solution from water. Chemical structure, swelling and fracture morphology of the nanocomposites membranes were studied. It was observed that PANI had a great impact on the chromium removal. Permeate flux and rejection of chromium(VI) were demonstrated for various pHs and chromium(VI) concentrations. Finally, influences of comonomer composition on the thermal properties of the copolymers were investigated to input their structure property relation.
47
Anton, Peter, and André Laschewsky. "Polysoaps via alternating olefin/SO2 copolymers." Universität Potsdam, 1991. http://opus.kobv.de/ubp/volltexte/2008/1721/.
Full textAbstract:
Contents:
Introduction
Results and discussion
- Monomers studied
- Monomer properties
- Polymerization, copolymer composition and general properties
- Polymer properties in aqueous solution
Conclusion
Experimental part
- Materials
- Copolymerization with S02 (typical procedure)
- Methods
48
Biemond, Gerard Jan Eduard. "Hydrogen bonding in segmented block copolymers." Enschede : University of Twente, 2006. http://doc.utwente.nl/51102.
Full text
49
Henderson, Paul Thomas. "Thiophene : alkylthiophene copolymers from substituted oligothiophenes." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/30555.
Full text
50
Zhu, Jiayi. "Interfacial behaviour of ionic block copolymers." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41039.
Full textAbstract:
The surface properties of quaternized poly(styrene-block-4-vinylpyridinium) AB block copolymers in monolayers spread at the air/water interface were thoroughly studied using the Langmuir film balance technique and microscopy techniques (i.e. transmission electron microscopy and atomic force microscopy). The effects of both molecular structure (i.e. chain lengths of the two blocks, alkyl chain length, and the counterion of the quaternizing agent) and the experimental parameters (i.e. measurement temperatures, salt species and salt concentrations in the aqueous subphase, compression rates, and hysteresis) on interfacial behaviour of the ionic block copolymers were explored. Optimum conditions for the deposition of polymer monolayers from a water surface to a solid substrate for the microscopy studies were also investigated. Evidence for novel surface micelle formation is presented. Three morphologies of surface micelles (i.e. plane, rod, and starfish) are identified for the block copolymers. The appearance of each morphology is found to be related only to the relative chain lengths of the two blocks. Methods of calculating aggregation numbers in starfish micelles are developed. A phase transition phenomenon is observed in surface pressure-area isotherms of the polymer monolayers. This phase transition is found to be related to the pressure-induced solubilization process of the quaternized poly(4-vinylpyridinium) hydrophilic block chains. A model of a starfish-to-jellyfish transition is introduced to describe this phase transition phenomenon.