Dissertations / Theses on the topic 'Polymer networks'
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1
Dean, Katherine (Katherine Maree) 1974. "Epoxy-dimethacrylate interpenetrating polymer networks." Monash University, School of Physics and Materials Engineering, 2002. http://arrow.monash.edu.au/hdl/1959.1/7791.
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Dean, Katherine(Katherine Maree) 1974. "Epoxy-dimethacrylate interpenetrating polymer networks." Monash University, School of Physics and Materials Engineering, 2002. http://arrow.monash.edu.au/hdl/1959.1/8231.
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Masoud, Hassan. "Polymer networks: modeling and applications." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45772.
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Polymer networks are an important class of materials that are ubiquitously found in natural, biological, and man-made systems. The complex mesoscale structure of these soft materials has made it difficult for researchers to fully explore their properties. In this dissertation, we introduce a coarse-grained computational model for permanently cross-linked polymer networks than can properly capture common properties of these materials. We use this model to study several practical problems involving dry and solvated networks. Specifically, we analyze the permeability and diffusivity of polymer networks under mechanical deformations, we examine the release of encapsulated solutes from microgel capsules during volume transitions, and we explore the complex tribological behavior of elastomers. Our simulations reveal that the network transport properties are defined by the network porosity and by the degree of network anisotropy due to mechanical deformations. In particular, the permeability of mechanically deformed networks can be predicted based on the alignment of network filaments that is characterized by a second order orientation tensor. Moreover, our numerical calculations demonstrate that responsive microcapsules can be effectively utilized for steady and pulsatile release of encapsulated solutes. We show that swollen gel capsules allow steady, diffusive release of nanoparticles and polymer chains, whereas gel deswelling causes burst-like discharge of solutes driven by an outward flow of the solvent initially enclosed within a shrinking capsule. We further demonstrate that this hydrodynamic release can be regulated by introducing rigid microscopic rods in the capsule interior. We also probe the effects of velocity, temperature, and normal load on the sliding of elastomers on smooth and corrugated substrates. Our friction simulations predict a bell-shaped curve for the dependence of the friction coefficient on the sliding velocity. Our simulations also illustrate that at low sliding velocities, the friction decreases with an increase in the temperature. Overall, our findings improve the current understanding of the behavior of polymer networks in equilibrium and non-equilibrium conditions, which has important implications for synthesizing new drug delivery agents, designing tissue engineering systems, and developing novel methods for controlling the friction of elastomers.
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Glaser, Jens. "Semiflexible Polymer Networks." Doctoral thesis, Universitätsbibliothek Leipzig, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-70576.
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Die vorliegende Arbeit beschäftigt sich mit der theoretischen Beschreibung der komplexen physikalischen Eigenschaften von Netzwerken semiflexibler Polymere. Ausgehend vom mathematischen Modell eines semiflexiblen Polymers, der \"wurmartigen Kette\" (wormlike chain), werden zwei wesentlich neue Konzepte zur Beschreibung dieses ungeordneten Materialzustands eingeführt. Einerseits wird das experimentell beobachtete, glasähnliche Fließen solcher Materialien durch das phänomenologische Modell eines semiflexiblen Polymers mit verallgemeinerter Reibung beschrieben, welche den Gesamteffekt der physikalischen oder auch chemischen Wechselwirkungen der Polymere untereinander widerspiegelt. Andererseits wird das bestehende Konzept der durch seine Nachbarfilamente erzeugten röhrenförmigen Einsperrung eines Filaments erweitert und die experimentell nachgewiesene, räumlich veränderliche Struktur der Röhre erklärt. Die erzielten Ergebnisse werden durch Rechnersimulationen sowie durch experimentelle Daten gestützt.
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Mendez, James D. "Conjugated Polymer Networks and Nanocomposites." Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1282841324.
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Markotsis, Martin G. School of Chemical Engineering & Industrial Chemistry UNSW. "Morphological studies of sbs based interpenetrating polymer networks." Awarded by:University of New South Wales. School of Chemical Engineering and Industrial Chemistry, 2005. http://handle.unsw.edu.au/1959.4/32833.
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Interpenetrating polymer networks (IPNs) of polystyrene-polybutadiene-polystyrene (SBS) block copolymers and polystyrene (PS) were prepared using sequential network formation with the polybutadiene (PB) of the SBS crosslinked thermally and the styrene network formed thermally or by ??-radiation. The use of ??-radiation to cure the added PS network at room temperature successfully avoided thermal degradation of the butadiene segments within the SBS which had been observed in earlier studies. Both linear SBS and radial SB4 IPNs were studied to compare the influence of linear or branched block copolymers on the IPN morphology. The molecular morphology was examined using a suite of techniques including thermal analysis (DSC and DMA), transmission electron microscopy (TEM), atomic force microscopy (AFM) and smallangle X-ray and neutron scattering (SAXS and SANS). The primary SBS/SB4 network morphology was found to dominate the IPN morphology with the secondary styrene network limited to selectively swelling the PS domains. The linear SBS IPNs displayed a more ordered morphology than the radial SB4 IPNs, and this morphology was investigated in pseudo three-dimensions by sectioning samples in two perpendicular directions. The morphology was found to be consistent with thermally formed systems prepared in previous studies, and contained styrenic domains of 20-50 nm within a continuous butadiene matrix. The weight of evidence suggested that the lamella structure dominated the linear SBS IPNs and a cylindrical structure for the radial SB4 IPNs. Maximum values of tensile strength and elongation at break (20 MPa and 140% respectively) were observed in samples with a styrene cure ??-radiation dose of 200 kGy. The SANS analysis of these polymer systems was expanded to investigate the thermal formation of the added PS network in real time. Time-resolved SANS allowed the development of nanostructures in the bulk samples to be measured, and compared to previous time-independent TEM studies on thin sections. The formation of the styrene network was most noticeably observed in a linear SBS IPN system, in which an increase in long-range order was observed and attributed to movement of styrene monomer into the styrenic domains and sharpening of the phase boundaries between the PS and the PB regions.
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Joyce, Steven John. "The topological trapping of cyclic polymers into polymer networks." Thesis, University of York, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306470.
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Vaughan, Asa Dee Byrne Mark E. "Reaction analysis of templated polymer systems." Auburn, Ala., 2008. http://hdl.handle.net/10415/1538.
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Dessaud, Nathalie. "Physics of polymer networks." Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.400569.
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Billen, Joris. "Simulated Associating Polymer Networks." Scholarship @ Claremont, 2012. http://scholarship.claremont.edu/cgu_etd/51.
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Telechelic associating polymer networks consist of polymer chains terminated by endgroups that have a different chemical composition than the polymer backbone. When dissolved in a solution, the endgroups cluster together to form aggregates. At low temperature, a strongly connected reversible network is formed and the system behaves like a gel. Telechelic networks are of interest since they are representative for biopolymer networks (e.g. F-actin) and are widely used in medical applications (e.g. hydrogels for tissue engineering, wound dressings) and consumer products (e.g. contact lenses, paint thickeners).
In this thesis such systems are studied by means of a molecular dynamics/Monte Carlo simulation. At first, the system in rest is studied by means of graph theory. The changes in network topology upon cooling to the gel state, are characterized. Hereto an extensive study of the eigenvalue spectrum of the gel network is performed. As a result, an in-depth investigation of the eigenvalue spectra for spatial ER, scale-free, and small-world networks is carried out. Next, the gel under the application of a constant shear is studied, with a focus on shear banding and the changes in topology under shear. Finally, the relation between the gel transition and percolation is discussed.
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Vandoolaeghe, Wendy Leigh. "Polymer networks at surfaces." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53552.
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Thesis (MSc)--Stellenbosch University, 2003.ENGLISH ABSTRACT: In this thesis the formation and properties of a polymer gel on and at a surface are investigated. The gel under investigation is defined as a three-dimensional network of macromolecules that form permanent links with one another and also with confining planar surfaces. The precise location of the crosslinks on the wall or on another macromolecule is not known prior to linking, and will differ from sample to sample. However, once the crosslinks are formed, they are assumed to be permanent. This random linking is the source of the disorder in the system, over which a quenched average has to be taken. An existing model [9] of network formation, with polymer-polymer crosslinks, is extended to incorporate a surface and polymersurface crosslinks. Within the framework of replica theory, statistical averages and physical properties of the system are calculated by means of a variational approach. Macroscopic information, in terms of the free energy of deformation, is obtained by using two different potentials to simulate the erosslinks mathematically.
AFRIKAANSE OPSOMMING: In hierdie tesis word die vorming en eienskappe van 'n polimeergel, wat teen 'n oppervlak gevorm word, ondersoek. Die gel word gedefinieer as 'n drie-dimensionele netwerk van makromolekules wat permanente bindings met mekaar, maar ook met twee inperkende, platvlakke, vorm. Die presiese ligging van die bindings op die muur en op ander makromolekules is nie vooraf bekend nie, en sal verskil van een gel-monster tot die volgende. Sodra die konneksies egter gevorm is, word aanvaar dat hulle permanent is. Die lukrake bindingsproses is die oorsprong van wanorde in die sisteem, waaroor 'n wanorde-gemiddelde bereken moet word. 'n Bestaande model [9]van netwerkvorming, met polimeer-polimeer bindings, word uitgebrei om 'n oppervlakte en polimeer-oppervlak bindings in te sluit. Statistiese fisika gemiddeldes en fisiese eienskappe van die sisteem word binne die raamwerk van replika-teorie en 'n variasie benadering bereken. Makroskopiese inligting, in terme van die vrye energie van vervorming, word verkry deur twee verskillende potensiale te gebruik om die konneksies wiskundig voor te stel.
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Rosenthal-Kim, Emily Quinn. "Green Polymer Chemistry: Synthesis of Poly(disulfide) Polymers and Networks." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1386525065.
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Kokil, Akshay. "Conjugated Polymer Networks: Synthesis and Properties." online version, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=case1121451946.
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Köhler, Werner. "Hot colloids in polymer networks." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-179496.
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Vandoolaeghe, Wendy Leigh. "Stress relaxation in polymer networks." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614364.
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Higgs, Paul G. "Biological and synthetic polymer networks." Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306415.
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Mahmad, Rasid Irina. "Dynamics of associative polymer networks." Thesis, Massachusetts Institute of Technology, 2021. https://hdl.handle.net/1721.1/130675.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, February, 2021Cataloged from the official PDF of thesis.
Includes bibliographical references.
Associative polymer networks are a versatile class of materials as demonstrated by their use in a wide variety of applications including biomaterials, viscosity modifiers and underwater adhesives. The viscoelastic and transport properties displayed by these associative networks can be tuned by careful design of the polymers that make up the network, as well as the transient interactions between them. Thus, elucidating the relationship between the molecular level details and the observed macroscopic properties is of high importance to further advance our understanding of associative networks. However, the complex dynamics displayed by these materials over a wide range of length and time scales present a significant challenge in studying this relation. This thesis aims to provide insights into the molecular origin of the dynamics of associative polymer networks.
The first part of this thesis investigates the molecular origin of shear thinning in associative networks through the design of a model associative polymer and a custom-built set-up referred to as "rheo-fluorescence" to quantify force-induced bond dissociation under shear flow. Comparison to existing models in transient network theory then demonstrate that retraction of dangling chains alone is insufficient to account for shear thinning in the model associative polymer network. Additional modes are likely contributing to the observed shear thinning behavior. The second part of this thesis focuses on the effect of sticker density, sticker clustering and entanglements on the dynamics of the associative networks through combined studies of self-diffusion performed using forced Rayleigh scattering (FRS) and rheology.
All three studies were performed using well-defined polymers with the same chemical composition such that the observed effects are solely due to the changes in sticker density, clustering and entanglements introduced during synthesis. The combined FRS and rheology studies on the effect of sticker density using a set of random copolymers revealed apparent superdiffusive scaling for chains with up to 15 stickers. This finding demonstrates that molecular hopping and thus, deviation from predictions of mean-field models persists to a higher limit than expected. To study the effect of sticker clustering, a polymer with clustered stickers was synthesized such that the molecular weight and sticker density were comparable to the random copolymers. It is demonstrated that the network topology is significantly altered by sticker clustering as evidenced by the opposite trends observed in the FRS and rheology measurements.
Finally, the onset of entanglements was examined by performing FRS and rheology measurements on a high molecular polymer, prepared at concentrations that span the unentangled to the weakly entangled regime. A clear transition seen in the self-diffusion measurements demonstrates the advantage of FRS to study the transition regimes where other techniques like rheology only show subtle changes.
by Irina Mahmad Rasid.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Materials Science and Engineering
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Tehrani, Mohammad Jafari. "Micromechanical Analysis of Strength of Polymer Networks with Polydisperse Structures." Ohio University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1491913532934372.
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Ni, Yiping. "Polymer networks architecture using supramolecular interactions." Phd thesis, Université Jean Monnet - Saint-Etienne, 2012. http://tel.archives-ouvertes.fr/tel-00952090.
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Supramolecular polymer networks are prepared basing on two different supramolecular interactions, ionic interaction and hydrogen bonds interaction. Ionic interaction was introduced in P(BMA-co-MA) with CaCO3 as a filler. The presence of Ca2+ is confirmed with X-ray diffraction by the apperence of specific ionic peak. The hydrogen bond interaction was introduced by two approaches. One is to first prepare a supramolecular monomer bearing DA moiety then supramolecular polymer P(MAAM-co-St) and P(MAP-co-St) are prepared by polyaddition. In the other approach, the supramolecular polymer is synthesized by one-step PUU polycodensation from the reagent containing multiple-hydrogen-bond sequence. The presence of intermolecular hydrogen bonds is detected by FTIR qualitatively, and the strengh, quantified as Kass, is calculated by 1H-NMR for different moieties respectively. Solubility tests indicate that the introduction of supramolecular interaction in the traditional polymers leads to the crosslinking in different extents. Consequently, materials are strengthened showing better thermo-endurence property and higher modulus when the content of supramolecular moiety is increased. Furthermore, rheological analysis is performed to investigate the viscoelasticity and to track the thermo reversibility
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Müller-Nedebock, Kristian Kurt. "Statistical mechanical properties of polymer networks." Thesis, University of Cambridge, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627493.
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Anderson, Kimberley Lana. "Synthesis of functionalised, crosslinked polymer networks." Thesis, University of Strathclyde, 2016. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=27948.
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Crosslinked polymer networks that are largely insoluble and tolerant to various chemical environments are useful in solid-supported chemistries and as sorbents in chemical separation. The selective retention of organic pollutants is an area of environmental importance for the clean-up of contaminated water sources, and a family of ion-exchange hypercrosslinked polymer particles have recently been developed for use as mixed-mode solid phase extraction sorbents. Expanding this family of polymers will give rise to a greater range of materials with enhanced selectivity and capacity for specific analytes of environmental concern. This work is an investigation of methods to synthesise and functionalise crosslinked polymer networks with ion-exchange character. The approaches explored for the synthesis of crosslinked polymers containing aromatic rings bridged by methylene (–CH2) chains include phenol-formaldehyde inspired chemistry, precipitation polymerisation, and Friedel Crafts chemistry. Weak anion-exchange character was imparted by the introduction of tertiary amine groups through post-polymerisation chemical modification reactions. Furthermore, by utilising amino acid derived alkyl esters it was proposed that there could be potential to exploit the weak cation-exchange character of the deprotected carboxylic acid and harness and exploit zwitterionic character. The use of precipitation polymerisation to synthesise poly(divinylbenzene-co-vinylbenzyl chloride) yielded spherical particles of low polydispersity in the 2-5 μm size range, with tuneable particle size and porosity (0-740 m2/g). Subsequent hypercrosslinking using Friedel-Crafts chemistry produced microporous polymers with a high concentration of micropores and ultra-high specific surface areas (1,900 m2/g). Amino acid derived esters, including sarcosine methyl and ethyl esters, and the L- and D- enantiomers of phenylalanine methyl ester, were utilised in a post-polymerisation amination study to impart weak anion-exchange character into the polymers at a level of around 1 mmol/g. Through evaluation of the macroreticular and hypercrosslinked variants as mixed-mode solid phase-extraction sorbents for the extraction of spiked organic analytes from ultra-pure water, it was found that these sorbents possess additional and useful functionality that is distinct from the weak anion-exchange polymeric sorbents that have been reported previously.
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Lu, Xihua. "Polymer hydrogel nanoparticles and their networks." Thesis, University of North Texas, 2002. https://digital.library.unt.edu/ark:/67531/metadc3232/.
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The thermally responsive hydroxypropyl cellulose (HPC) hydrogel nanoparticles have been synthesized and characterized. The HPC particles were obtained by chemically crosslinking collapsed HPC polymer chains in water-surfactant (dodecyltrimethylammonium bromide) dispersion above the lower critical solution temperature (LCST) of the HPC. The size distributions of microgel particles, measured by dynamic light scattering, have been correlated with synthesis conditions including surfactant concentration, polymer concentration, and reaction temperature. The swelling and phase transition properties of resultant HPC microgels have been analyzed using both static and dynamic light scattering techniques. By first making gel nanoparticles and then covalently bonding them together, we have engineered a new class of gels with two levels of structural hierarchy: the primary network is crosslinked polymer chains in each individual particle, while the secondary network is a system of crosslinked nanoparticles. The covalent bonding contributes to the structural stability of the nanostructured gels, while self-assembly provides them with crystal structures that diffract light, resulting in colors. By using N-isopropylacrylamide copolymer hydrogel nanoparticles, we have synthesized nanoparticle networks that display a striking iridescence like precious opal but are soft and flexible like gelatin. This is in contrast to previous colored hydrogels, which were created either by adding dyes or fluorescent, or by organic solvent or by embedding a colloidal crystal array of polymer solid spheres . Creating such periodic 3D structures in materials allows us to obtain useful functionality not only from the constituent building blocks but also from the long-range ordering that characterizes these structures. Hydroxypropyl cellulose (HPC) and poly (acrylic acid ) (PAA) complexes were studied using turbidity measurement and laser light scattering. The phase transition temperature of the complexes is found to depend on pH and molecular weights of PAA and HPC. The driving force for this phenomenon is due to the hydrogen bonding and hydrophobic interaction of the macromolecules. Based on the principle of the PAA/HPC complexes, the PAA nanoparticles were synthesized in 0.1wt % HPC aqueous solution at room temperature.
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Alt, Eric Allen. "Structural modeling of dynamic polymer networks." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122711.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemistry, 2019Cataloged from PDF version of thesis.
Includes bibliographical references (pages 125-131).
Polymer network based gels are an important class of materials with a wide range of applications. Dynamic polymer networks, which crosslink via the formation of reversible bonds, in particular have great potential as stimuli responsive, mechanically tunable, and self-healing materials. Many important emergent properties of these materials, such as mechanical strength, are mediated by their underlying network structure, which can be characterized by the network topology and spatial distribution of nodes. Therefore, unlocking the full potential of these materials through rational design requires an understanding of how network structure arises as a function of network-forming precursor design. Because the bonds that crosslink dynamic polymer networks are reversible, stresses initially present or otherwise induced in these systems can be relieved through network rearrangement. As such, given sufficient time to relax, the network structure is determined by equilibrium thermodynamics.
This work presents a thermodynamic formalism which characterizes the free energy of a network in terms of node positional, network topological, and polymer conformational entropies. Through this lens, and aided by numerical calculations and simulations of model networks, we show how the free energy landscape with respect to density relates to factors which can be readily controlled through precursor design, such as polymer length and node size. Additionally, Monte Carlo simulations of explicit networks reveal that thermodynamic relaxation can give rise to spatial heterogeneity in the arrangement of network nodes. In the last chapter we use the tools developed in the earlier chapters to explore how these same design parameters influence the topological statistics of equilibrium networks. In addition to showing how internode connectivity increases with polymer length and system density, we find that inhomogeneity due to spatial relaxation can also lead to greater network connectivity.
Finally, we explore the weakening of network topologies due to substitution of polymer-linked node forming components with topologically non-functional counterparts, finding that larger nodes fare better than their smaller counterparts in maintaining network connectivity when these substitutions are made.
by Eric Allen Alt.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Chemistry
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Chung, Taekwoong. "New Shape Memory Effects in Semicrystalline Polymeric Networks." Cleveland, Ohio : Case Western Reserve University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1238406068.
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Thesis (Ph.D.)--Case Western Reserve University, 2009Abstract Department of Macromolecular Science and Engineering Title from PDF (viewed on 14 April 2009) Available online via the OhioLINK ETD Center
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Köhler, Werner. "Hot colloids in polymer networks: cage formation and transient network deformation." Diffusion fundamentals 20 (2013) 13, S. 1, 2013. https://ul.qucosa.de/id/qucosa%3A13535.
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Noss, Kimberly RyAnne Byrne Mark E. "The rational design of recognitive polymeric networks for sensing applications." Auburn, Ala, 2009. http://hdl.handle.net/10415/1704.
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Heussinger, Claus. "On the Elasticity of Stiff Polymer Networks." Diss., lmu, 2007. http://nbn-resolving.de/urn:nbn:de:bvb:19-77447.
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Tang, Shengchang Ph D. Massachusetts Institute of Technology. "Dynamics and mechanics of associating polymer networks." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/107874.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemical Engineering, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references.
Associating polymers have attracted much interest in a variety of applications such as selfhealing materials, biomaterials, rheological modifiers, and actuators. The interplay of polymer topology and sticker chemistry presents significant challenges in understanding the physics of associating polymers across a wide range of time and length scales. This thesis aims to provide new insights into the structure-dynamics-mechanics relationships of associating polymer networks. This thesis first examines diffusion of various types of associating polymers in the gel state through a combination of experiment and theory. By using forced Rayleigh scattering (FRS), phenomenological super-diffusion is revealed as a general feature in associating networks. Experimental findings are quantitatively explained by a simple two-state model that accounts for the interplay of chain diffusion and the dynamic association-dissociation equilibrium of polymer chains with surrounding network. Furthermore, hindered self-diffusion is shown to directly correlate with a deviation from the Maxwellian behavior in materials rheological response on the long time scale. To further understand how sticker dynamics affects the network mechanical properties, a new method referred to as "sticker diffusion and dissociation spectrometry" is developed to quantify the dissociation rate of stickers in the network junctions. It is demonstrated that sticker dissociation is a prerequisite step for sticker exchange that leads to macroscopic stress relaxation. Finally, this thesis explores the use of fluorescence recovery after photobleaching (FRAP) to measure self-diffusion of associating polymers, and a mathematical framework is established. The second part of this thesis focuses on the development of new methods of controlling the mechanical properties of associating networks through engineering the molecular structure of polymer chains. Specifically, topological entanglement is introduced into the network through extending the polymer chains to reach beyond their entanglement threshold. This strategy drastically enhances material's toughness, extensibility, creep resistance and stability in solutions. Various types of coupling chemistries are then explored to fine tune the extent of entanglement. The entanglement effect and the long-time relaxation of materials can be further controlled by introducing branching points into the macromolecules.
by Shengchang Tang.
Ph. D.
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Authimoolam, Sundar Prasanth. "BIOMIMETIC ORAL MUCIN FROM POLYMER MICELLE NETWORKS." UKnowledge, 2015. http://uknowledge.uky.edu/cme_etds/51.
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Mucin networks are formed by the complexation of bottlebrush-like mucin glycoprotein with other small molecule glycoproteins. These glycoproteins create nanoscale strands that then arrange into a nanoporous mesh. These networks play an important role in ensuring surface hydration, lubricity and barrier protection. In order to understand the functional behavior in mucin networks, it is important to decouple their chemical and physical effects responsible for generating the fundamental property-function relationship. To achieve this goal, we propose to develop a synthetic biomimetic mucin using a layer-by-layer (LBL) deposition approach. In this work, a hierarchical 3-dimensional structures resembling natural mucin networks was generated using affinity-based interactions on synthetic and biological surfaces. Unlike conventional polyelectrolyte-based LBL methods, pre-assembled biotin-functionalized filamentous (worm-like) micelles was utilized as the network building block, which from complementary additions of streptavidin generated synthetic networks of desired thickness. The biomimetic nature in those synthetic networks are studied by evaluating its structural and bio-functional properties. Structurally, synthetic networks formed a nanoporous mesh. The networks demonstrated excellent surface hydration property and were able capable of microbial capture. Those functional properties are akin to that of natural mucin networks. Further, the role of synthetic mucin as a drug delivery vehicle, capable of providing localized and tunable release was demonstrated. By incorporating antibacterial curcumin drug loading within synthetic networks, bacterial growth inhibition was also demonstrated. Thus, such bioactive interfaces can serve as a model for independently characterizing mucin network properties and through its role as a drug carrier vehicle it presents exciting future opportunities for localized drug delivery, in regenerative applications and as bio-functional implant coats.
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Mateyisi, Mohau Jacob. "Polymer networks with mobile force-applying crosslinks." Thesis, Stellenbosch : University of Stellenbosch, 2011. http://hdl.handle.net/10019.1/6759.
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Thesis (MSc)--University of Stellenbosch, 2011.ENGLISH ABSTRACT: We construct and study a simple model for an active gel of exible polymer filaments crosslinked by a molecular motor cluster that perform reversible work while translating along the filaments. The filament end points are crosslinked to an elastic background. In this sense we employ a simplified model for motor clusters that act as slipping links that exert force while moving along the strands. Using the framework of replica theory, quenched averages are taken over the disorder which originates from permanent random crosslinking of network end points to the background. We investigate how a small motor force contributes to the elastic properties of the network. We learn that in addition to the normal elastic response for the network there is an extra contribution to the network elasticity from the motor activity. This depends on the ratio of the entropic spring constant for the linked bio-polymerchain to the spring constant of the tether of the motor.
AFRIKAANSE OPSOMMING: Ons konstrueer en bestudeer 'n eenvoudige model vir 'n aktiewe netwerk van eksieble polimeerfilamente wat deur grosse van molekulere motors aan mekaar verbind word wat omkeerbare werk doen terwyl dit langs die filamente transleer. Die eindpunte van die filamente is aan 'n elastiese agtergrond verbind. In hierdie sin benut ons 'n eenvoudige model vir motorclusters wat as verskuifbare verbindings krag op die filamente tydens beweging kan uitoefen. Nie-termiese wanorde gemiddeldes word geneem oor die wanorde wat deur die lukrake permanente verbindings van netwerk eindpunte aan die agtergrond veroorsaak word. Ons ondersoek hoe 'n klein motorkrag tot die elastiese eienskappe van die netwerk bydra. Ons leer dat daar bo en behalwe die gewone elastiese respons vir die netwerk 'n elastiese bydrae as gevolg van die motors se aktiwiteit voorkom. Dit hang af van die verhouding van die entropiese veerkonstante van die biopolimerketting tot die veerkonstante van die anker van die motor.
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Guo, Ruilan. "Dependence of physical and mechanical properties on polymer architecture for model polymer networks." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22642.
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Thesis (Ph. D.)--Polymer, Textile and Fiber Engineering, Georgia Institute of Technology, 2008.Committee Chair: Karl I. Jacob; Committee Member: Anselm C. Griffin; Committee Member: C. P. Wong; Committee Member: Rina Tannenbaum; Committee Member: William J. Koros; Committee Member: Yonathan S. Thio.
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Nilsson, Camilla. "Dendrimers : Synthesis, Characterization and Use in Thiol-Ene Networks." Doctoral thesis, KTH, Fiber- och polymerteknik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9763.
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Dendrimers are perfectly branched, well-defined macromolecules with a layered structure and a large amount of peripheral end groups. The high functionality in combination with the possibility of dendrimers to adopt a globular shape at high molecular weights, gives them very unique properties.In this work dendrimers up to fifth generation based on 2,2-bis(methylol)propionic acid (bis-MPA) were synthesized with different core structures. The core moieties were chosen in aspects of functionality and flexibility and the impact of the core on the physical and rheological properties was studied. By using the divergent growth approach dendrimers with acetonide, hydroxyl, allyl ether and methacrylate end groups were obtained.The bulk properties of the acetonide- and hydroxyl- terminated dendrimers were investigated with a rheometer. Temperature sweep tests were performed on the acetonide protected dendrimers in a temperature range of -50 up to 120°C at a constant frequency of 1 Hz. It was observed that the glass transition temperature (Tg) increased with increasing generation and that the modulus dropped without a trace of rubbery plateau for lower generations. This lack of rubbery plateau is due to the absence of entanglements between dendrimers. Interestingly, a small rubbery plateau was visible for generation five which implies enhanced interactions between the dendrimers. This behaviour suggests to be strongly influenced by the structural collapse at higher generations. Further, frequency sweep tests were performed on hydroxyl functional dendrimers at different temperatures. The results revealed Newtonian properties for lower generations and shear-thinning behaviour for higher generations at high frequency.Furthermore, this research involves the creation of well-defined thiol-ene networks by incorporation of allyl ether or methacrylate functional dendrimers in thermosets. This was accomplished by using two trithiols of different molecular weights and react them with the enes under UV irradiation. The thiol-methacrylate crosslinking reaction resulted in inhomogeneous films with and residual unsaturations. The thiol-ene films based on allyl ether dendrimers, on the contrary, resulted in homogeneous films with intermolecular couplings between the ene and the thiol being the dominant mode of polymerization.Dendrimerer är perfekt grenade, väldefinierade molekyler med en struktur indelad i lager och med ett stort antal ändgrupper. Dendrimerer har, på grund av sina många funktionella grupper och sin förmåga att vid höga molekylvikter anta en mer sfärisk struktur, väldigt speciella egenskaper. Dendrimerer upp till femte generation, baserade på 2,2-dimetylolpropan syra (bis-MPA), har syntetiserats med olika typer av kärnstrukturer. Kärnorna valdes med avseende på funktionalitet och flexibilitet, och strukturens påverkan på dendrimerernas fysikaliska och reologiska egenskaper undersöktes. Dendrimerer med acetonid-, hydroxyl-, allyleter- samt metakrylatändgrupper syntetiserades genom att använda en divergent syntesmetod. De hydroxyl- och acetonidfunktionella dendrimerernas reologiska egenskaper i bulk karakteriserades med en reometer. De acetonidskyddade dendrimererna karakteriserades med temperatursvep i ett intervall mellan -50 °C och 120°C och med en konstant frekvens på 1 Hz. Analyserna visade att glastransitionstemperaturen (Tg) ökade med ökande generation och att dendrimerer av lägre generation inte uppvisade någon gummiplatå. Anledningen till detta är att det inte förekommer några kedjeintrasslingar mellan dendrimerer. Dock uppvisar femte generationens dendrimerer liten gummiplatå vilket pekar på ökade interaktioner mellan dem. Detta beteende påverkas av att dendrimerna kollapsar vid höga generationer och att förändringen i strukturen tydligt påverkar interaktionerna. Hydroxylfunktionella dendrimererna karaktäriserades med frekvessvep vid olika temperaturer. Det visade sig att lägre generationer uppvisar Newtonskt beteende medan högre generationer visar sig vara skjuvförtunnande vid höga frekvenser. Som en ytterligare del i detta projekt skapades väldefinierade tiol-en nätverk genom att reagera allyleter och metakrylat-funktionella dendrimerer med två trifunktionella tioler av olika molekylvikt. Reaktionerna initierades med UV-ljus. Tiol-metakrylat filmerna visade på en hög andel homopolymerisation vilket resulterade i inhomogent tvärbundna nätverk med ett stort antal oreagerade grupper. Tiol-allyleter filmerna visade uppvisade däremot homogena nätverk med en liten andel homopolymerisation.
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Kawamura, Takanobu. "STRUCTURE AND PHYSIC0CHEMICAL PROPERTIES OF ENDLINKLED POLYMER NETWORKS." 京都大学 (Kyoto University), 2001. http://hdl.handle.net/2433/150697.
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Tsoi, Kit-hon. "Aspects of the statistics of condensation polymer networks." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/hkuto/record/B38985433.
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Tsoi, Kit-hon, and 徐傑漢. "Aspects of the statistics of condensation polymer networks." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B38985433.
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Andrews, G. P. "Physicochemical characterisations of novel pharmaceutical polymer gel networks." Thesis, Queen's University Belfast, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397846.
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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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Baxandall, L. G. "A statistical mechanical approach to transient polymer networks." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372878.
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Lydon, Fiona Jane. "Novel hydrogel copolymers and semi-interpenetrating polymer networks." Thesis, Aston University, 1994. http://publications.aston.ac.uk/9646/.
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Interpenetrating polymer networks (lPN's), have been defined as a combination of two polymers each in network form, at least one of which has been synthesised and / or crosslinked in the presence of the other. A semi-lPN, is formed when only one of the polymers in the system is crosslinked, the other being linear. lPN's have potential advantages over homogeneous materials presently used in biomedical applications, in that their composite nature gives them a useful combination of properties. Such materials have potential uses in the biomedical field, specifically for use in hard tissue replacements, rigid gas permeable contact lenses and dental materials. Work on simply two or three component systems in both low water containing lPN's supplemented by the study of hydrogels (water swollen hydrophilic polymers) can provide information useful in the future development of more complex systems. A range of copolymers have been synthesised using a variety of methacrylates and acrylates. Hydrogels were obtained by the addition of N-vinyl pyrrolidone to these copolymers. A selection of interpenetrants were incorporated into the samples and their effect on the copolymer properties was investigated. By studying glass transition temperatures, mechanical, surface, water binding and oxygen permeability properties samples were assessed for their suitability for use as biomaterials. In addition copolymers containing tris-(trimethylsiloxy)-y-methacryloxypropyl silane, commonly abbreviated to 'TRlS', have been investigated. This material has been shown to enhance oxygen permeability, a desirable property when considering the design of contact lenses. However, 'TRIS' has a low polar component of surface free energy and hence low wettability. Copolymerisation with a range of methacrylates has shown that significant increases in surface wettability can be obtained without a detrimental effect on oxygen permeability. To further enhance to surface wettability 4-methacryloxyethyl trimellitic anhydride was incorporated into a range of promising samples. This study has shown that by careful choice of monomers it is possible to synthesise polymers that possess a range of properties desirable in biomedical applications.
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Bello, Carlos A. "Microsphere-aided characterization of stimuli-responsive polymer networks." [Tampa, Fla] : University of South Florida, 2008. http://purl.fcla.edu/usf/dc/et/SFE0002788.
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Zumbrum, Michael Allen. "Characterization of photocurable networks in real-time and post-exposure." Diss., This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-08032007-102234/.
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ROMANO, ANGELO. "Photo-responsive polymer networks for the design of polymer coatings with light-tunable properties." Doctoral thesis, Politecnico di Torino, 2021. http://hdl.handle.net/11583/2903512.
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Jones, Janette Louise. "The elasticity and growth of rigid networks." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359808.
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Hedrick, Jeffrey C. "High performance polymeric networks and thermoplastic blends : microwave versus thermal processing /." Diss., This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-07122007-103925/.
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Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1991.Vita. Abstract. No film copy made for this title. Includes bibliographical references (leaves 243-254). Also available via the Internet.
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Monemian, Seyedali. "Tuning Mechanics of Bio-Inspired Polymeric Materials through Supramolecular Chemistry." Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1467882025.
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Kawamoto, Ken Ph D. Massachusetts Institute of Technology. "Rational design of polymer networks and bottlebrush block copolymers." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/112516.
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Thesis: Ph. D. in Organic Chemistry, Massachusetts Institute of Technology, Department of Chemistry, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references.
Chapter 1: Introduction to Polymer Networks and Bottlebrush Block Copolymers We introduce polymer networks and the contribution of this author's thesis in the context of new polymer gel design and analysis of topological defects. We also introduce block copolymers and the key architectural differences between our branched bottlebrush design for block copolymer and liquid crystal block copolymer materials. Chapter 2: A dual role for 1,2,4,5-tetrazines in polymer networks: combining Diels-Alder reactions and metal coordination to generate functional supramolecular gels In this chapter we report the synthesis, characterization, and application of a new type of supramolecular metallogels using 1,2,4,5-tetrazines-containing polymers. This was the first example in our group of attempting to using metal-organic cages as crosslinking structures for polymer networks. Chapter 3: Loops Versus Branch Functionality in Model Click Hydrogels Here we report our work on quantifying topological defects in tri- and tetrafunctional networks and compare fundamental differences between such systems. We demonstrate the ability to count primary loop defects with a distribution of junction functionality. Chapter 4: Quantifying the Impact of Molecular Defects on Polymer Network Elasticity Based on our work in Chapter 3, we correlate the effect of molecular defects on a macroscopically measurable value: elasticity. We use our experimental techniques to help develop a new theory to accurately predict elasticity in end-linked networks. Chapter 5: Graft-through Synthesis and Assembly of Janus Bottlebrush Polymers from A-branch- B Diblock Macromonomers We synthesize branched macromonomers that contain two different polymers polymers to form bottlebrush block copolymers with a novel architecture. Bulk state and thin film self-assembly studies were performed and open the door to new, more complex bottlebrush block copolymers. Chapter 6: Synthesis of Liquid Crystal-Containing A-branch-B Janus Bottlebrush Block Copolymers We synthesize macromonomers that contains a polymer and a liquid crystal and polymerize the branched macromonomers to form Janus-type bottlebrush block copolymers. The bulk state self-assembly behavior was characterized and the alignment of the bottlebrush polymers under a magnetic field is explored.
by Ken Kawamoto.
Ph. D. in Organic Chemistry
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Glaser, Jens, Masashi Degawa, Inka Lauter, Rudolf Merkel, and Klaus Kroy. "Tube geometry and brownian dynamics in semiflexible polymer networks." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-188856.
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Glaser, Jens, Masashi Degawa, Inka Lauter, Rudolf Merkel, and Klaus Kroy. "Tube geometry and brownian dynamics in semiflexible polymer networks." Diffusion fundamentals 11 (2009) 7, S. 1-2, 2009. https://ul.qucosa.de/id/qucosa%3A13927.
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Kolz, Jürgen. "Ionic and nonionic polymer networks studied with magnetic resonance /." Aachen : Shaker, 2008. http://d-nb.info/991820800/04.
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Jurjiu, Aurel. "Dynamics of polymer networks modelled by finite regular fractals." [S.l. : s.n.], 2005.
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