Diffusion in Polymer Systems Studied by Fluorescence Correlation Spectroscopy PDF Download
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Author: Thipphaya Cherdhirankorn
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Author: Thipphaya Cherdhirankorn
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Author:
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Languages : en
Pages :
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Fluorescence correlation spectroscopy (FCS) is a powerful technique to determine the diffusion of fluorescence molecules in various environments. The technique is based on detecting and analyzing the fluctuation of fluorescence light emitted by fluorescence species diffusing through a small and fixed observation volume, formed by a laser focused into the sample. Because of its great potential and high versatility in addressing the diffusion and transport properties in complex systems, FCS has been successfully applied to a great variety of systems. In my thesis, I focused on the application of FCS to study the diffusion of fluorescence molecules in organic environments, especially in polymer melts. In order to examine our FCS setup and a developed measurement protocol, I first utilized FCS to measure tracer diffusion in polystyrene (PS) solutions, for which abundance data exist in the literature. I studied molecular and polymeric tracer diffusion in polystyrene solutions over a broad range of concentrations and different tracer and matrix molecular weights (Mw). Then FCS was further established to study tracer dynamics in polymer melts. In this part I investigated the diffusion of molecular tracers in linear flexible polymer melts [polydimethylsiloxane (PDMS), polyisoprene (PI)], a miscible polymer blend [PI and poly vinyl ethylene (PVE)], and star-shaped polymer [3-arm star polyisoprene (SPI)]. The effects of tracer sizes, polymer Mw, polymer types, and temperature on the diffusion coefficients of small tracers were discussed. The distinct topology of the host polymer, i.e. star polymer melt, revealed the notably different motion of the small tracer, as compared to its linear counterpart. Finally, I emphasized the advantage of the small observation volume which allowed FCS to investigate the tracer diffusions in heterogeneous systems; a swollen cross-linked PS bead and silica inverse opals, where high spatial resolution technique was required.
Author: Karel Procházka
Publisher: Springer
ISBN: 3319267884
Category : Science
Languages : en
Pages : 306
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Book Description
This volume describes the application of fluorescence spectroscopy in polymer research. The first chapters outline the basic principles of the conformational and dynamic behavior of polymers and review the problems of polymer self-assembly. Subsequent chapters introduce the theoretical principles of advanced fluorescence methods and typical examples of their application in polymer science. The book closes with several reviews of various fluorescence applications for studying specific aspects of polymer-solution behavior. It is a useful resource for polymer scientists and experts in fluorescence spectroscopy alike, facilitating their communication and cooperation.
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Languages : en
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Author: Ariel Michelman-Ribeiro
Publisher:
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Category :
Languages : en
Pages : 232
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Abstract: This dissertation investigates the transport of ions and particles and dynamics in polymer systems. The first study is of structural changes in agarose gels as ions migrate through them under applied electric fields (E-fields). The second is on the translational diffusion of probes in polymer solutions and gels, using poly(vinyl alcohol) (PVA) as a model system. Understanding the transport of particles and ionic migration is important for applications such as biomedical devices and gel electrophoresis. In the first study, I performed small-angle light scattering (SALS) on agarose gels in E-fields, and observed anisotropic SALS patterns, which developed more quickly at higher E-fields and were more anisotropic at higher polymer concentration. Analysis of the data using a model of oriented rods suggested that these patterns arose from rod-like domains 10-15 microns in length oriented perpendicular to the applied field. Microscope imaging revealed rod-like domains on the same length scale, also aligned perpendicular to the E-field. Profiles of pH variation across the gel, measured by video photography, indicated that the anisotropic patterns appeared when the H + and OH - ions, migrating in opposite directions, met. Calculations of pH profiles using a model based on electro-diffusion reproduced several features of the measured pH profiles. This study showed that electrolysis and the resulting ion migration produce pH changes that are correlated with macroscopic shrinking and orientation of the gel. In the second study, I used fluorescence correlation spectroscopy (FCS) to study probe diffusion in PVA solutions and cross-linked gels to obtain diffusion coefficients, D, of nanosized particles as a function of PVA concentration, c, and cross-link density. For probes smaller than the correlation length, x, of the polymer solution, diffusion followed D/D 0 = [Special characters omitted.], as suggested by various models, with n depending on solvent quality Diffusion of small particles (R
Author: R. Rigler
Publisher: Springer Science & Business Media
ISBN: 3642595421
Category : Science
Languages : en
Pages : 503
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Book Description
This is the first book-length treatment of both the theoretical background to fluorescence correlation spectroscopy (FCS) and a variety of applications in various fields of science. The high spatial and temporal resolution of FCS has made it a powerful tool for the analysis of molecular interactions and kinetics, transport properties due to thermal motion, and flow. It contains an essential contribution from Nobel Prize winner M. Eigen, who is credited with inventing FCS.
Author: Anand Rahalkar
Publisher:
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Category :
Languages : en
Pages :
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Polyelectrolyte gels have the ability to undergo volume transitions in response to external stimuli. As a result, they are used in a wide variety of applications such as sensors, actuators, artificial implants, and controlled drug delivery. In addition, diffusion of trapped macromolecules inside gels is of tremendous significance in drug delivery systems. In this thesis, the dynamics of trapped polyelectrolytes in a polyelectrolyte gel is studied using dynamic light scattering technique. The effect of the crosslink density and the charge density of the gel, as well as of solvent quality and salt concentration are investigated. In general, two distinct diffusive modes (fast and slow) are observed in light scattering experiments. We have discovered that the fast mode corresponds to the gel elasticity and the slow mode corresponds to diffusion of trapped polymer. The deduced diffusion coefficient of the trapped polymer obeys an exponential dependence on the volume fraction of the gel, in accordance with the presence of an entropic barrier for polymer diffusion. In addition, we have monitored the diffusion of a neutral polymer in polyelectrolyte gels using fluorescence correlation spectroscopy. We demonstrate that the polymer diffusion is considerably slowed down by the gel due to the coupling between polymer dynamics and gel dynamics.
Author: Mikheil Doroshenko
Publisher:
ISBN:
Category :
Languages : en
Pages : 113
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Author: Carol A. Roach
Publisher:
ISBN: 9781124480015
Category : Emission spectroscopy
Languages : en
Pages :
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Time resolved emission spectroscopy experiments have numerous applications within the physical sciences. For example, intrinsic and extrinsic fluorescent molecules are used in chemical and biological assays, monitoring of reactions, and imaging of structures. The need to study chemical and biological systems of greater complexity with fluorescent molecules has required the development of more sophisticated time resolved emission spectroscopic instruments, experimental techniques, and data analysis methods. Current research continues to provide new information on fundamental principles and properties of fluorescent molecules, information that is critical to proper interpretation of data generated by these more complex experiments. Chapter 4 of this dissertation discusses the development of a new instrument capable of performing full-spectrum fluorescence correlation spectroscopy. In Chapter 1 the advantages of full-spectrum fluorescence correlation spectroscopy, as well as proper interpretation of tryptophan fluorescence performed in Chapter 5, are discussed with conclusions, limitations, and concepts for future experiments presented in Chapter 6. Chapters 2 and 3 provide a background on fluorescence principles and multivariate analysis techniques as they apply to full-spectrum fluorescence correlation spectroscopy, and experiments involving tryptophan fluorescence interpretation that are presented in Chapter 5. For the first time, full spectra are collected during the course of fluorescence correlation spectroscopy measurements, allowing multivariate analysis to be applied to the data. Measurement of instrumental parameters for full-spectrum fluorescence correlation spectroscopy such as observation volume size, two-photon excitation capabilities, concentration limitations, and the range of observable diffusion coefficients are performed and compared to traditional fluorescence correlation spectroscopy instruments. An experimental application of the instrument to fluorescently labeled polystyrene particle diffusion in a polymer solution with a second fluorescent dye is shown. Separation of the two overlapped fluorescence spectra in this mixture by multivariate analysis is performed and diffusion coefficients are calculated. The results show that spectral resolution obtained by multivariate analysis of data collected with this novel instrument provides a method to reduce cross-talk in multicolor fluorescence correlation spectroscopy experiments. Experiments involving photokinetic matrix decomposition of time resolved emission decay matrices collected for the amino acid tryptophan and peptide mastoparan-X are performed. Tryptophan is a microenvironment sensitive fluorescent molecule that may naturally occur in proteins. The microenvironment sensitivity of tryptophan has been exploited to imply structural changes of proteins in time resolved fluorescence experiments, however tryptophan fluorescence photokinetics are complex. A controversy exists on the proper interpretation and use of tryptophan fluorescence, centered on the origin of the fluorescence from ground-state heterogeneity or excited-state reactions of the molecule. Photokinetic matrix decomposition of time resolved emission decay data has previously been able to differentiate between ground-state heterogeneity and excited state reaction photokinetics within other microenvironment sensitive fluorescent molecules, and is applied in this dissertation to the study of tryptophan fluorescence. Data collected with tryptophan and mastoparan-X suggest that ground-state heterogeneity is the source of complex tryptophan fluorescence decay in proteins.
Author: Abderrahim Boudenne
Publisher: John Wiley & Sons
ISBN: 1119972884
Category : Technology & Engineering
Languages : en
Pages : 1322
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Book Description
Multiphase polymeric systems include a wide range of materials such as composites, blends, alloys, gels, and interpenetrating polymer networks (IPNs). A one-stop reference on multiphase polymer systems, this book fully covers the preparation, properties, and applications of advanced multiphase systems from macro to nano scales. Edited by well-respected academics in the field of multiphase polymer systems, the book includes contributions from leading international experts. An essential resource for plastic and rubber technologists, filler specialists and researchers in fields studying thermal and electrical properties.
