The Dielectric Properties of Non-stoichiometric Polyelectrolyte Complexes PDF Download
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Author: David Austin Opp
Publisher:
ISBN:
Category :
Languages : en
Pages : 222
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Author: David Austin Opp
Publisher:
ISBN:
Category :
Languages : en
Pages : 222
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Author: A. Eisenberg
Publisher: Elsevier
ISBN: 0323156754
Category : Science
Languages : en
Pages : 304
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Book Description
Ion-Containing Polymers: Physical Properties and Structure is Volume 2 of the series Polymer Physics. This book aims to fill in the gap in literature regarding the physical aspects of ion-containing polymers. A total of five chapters comprise this book. The Introduction (Chapter 1) generally deals with the application of ion-containing polymers, general classification, and the available works regarding the subject. Chapter 2 establishes the concepts of supermolecular structure and glass transitions in terms of the effects of ionic forces in polymers. These chapters provide the context in the discussion of viscoelastic properties of homopolymers and copolymers in Chapters 3 and 4. Finally, Chapter 5 tackles the configuration-dependent properties of ion-containing polymers. This volume will be of particular help to students in the field of physics and chemistry.
Author: Huan Zhang (Polymer engineer)
Publisher:
ISBN:
Category : Photoelectrochemistry
Languages : en
Pages : 0
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Polyelectrolyte complexes (PECs) are formed based on the strong association of oppositely charged polyelectrolytes, a process driven by a combination of enthalpy and entropy, but often with entropic considerations dominating. PEC based materials including polyelectrolyte coacervates, precipitates, and multilayers (PEMs), exhibit promising application in a variety of areas. These abundant applications of PECs are made possible by their highly controllable/tailorable properties upon exposure to different stimuli like pH, salt, organic solvent, and so on. It is important to understand how these different parameters affect the complexation of polyelectrolytes and the structures of PECs. In this dissertation, the main goal is to investigate the effects of solution composition including salt content, pH of solution, and solvent quality on the properties of polyelectrolyte coacervate, precipitate and multilayers. Based on these studies, the potential of applications of PEC materials in self-healing, 3D printing under ethanol and adhesive were studied. Firstly, the interactions between various types of salt and polyelectrolytes were studied. The energetics of the binding process between salt and polyelectrolytes were investigated. Various types of cations and anions were employed in this study, including alkali metal, alkaline earth metal ions, transition metal ions and a Hofmeister series of anions. Based on the different interactions between these ions and polyelectrolytes, the salts present different effects on the properties of PECs. Salt effects on coacervate, especially coacervate stability, are summarized in Chapter III. Chapter IV shows the study of salt effects on the properties of PEMs including the growth and swelling/deswelling behaviors. In Chapter V, the effects of salt and pH on the self-healing ability of bulk PEC materials were studied. The rheological properties of hydrated, bulk PEC material are strongly influenced by salt and pH treatment, which directly controls the crosslink density in the material, chain mobility, and therefore self-healing ability. Alkali metal ions and transition metal ions show different effects on the self-healing ability of the BPEI/PAA complex. The effects of these two different types of salts on complex are reversible, which presents a possible way to control the material properties, ranging from self-healing to completely unable to do so. Due to changes in charge density of weak polyelectrolytes in response to pH, the self-healing of weak PECs can be enhanced by pH treatment as well. In Chapter VI, the effects of ethanol on the complexation of polyelectrolytes, rheological properties and structure of polyelectrolyte precipitates were investigated. The complexation of polyelectrolytes is inhibited by the presence of ethanol due to the weakening interactions between polycation and polyanion under low dielectric constant environment. For the polyelectrolyte precipitate formed from higher ethanol content mixture, the precipitate shows a smaller modulus and larger loss angle. In comparison, by immersing polyelectrolyte precipitate in a higher ethanol content mixture, the precipitate shows an increased modulus. This enhancement of mechanical properties is mainly due to the dehydration of the polyelectrolyte precipitate, which results in an enhanced interaction between BPEI and PAA (lowering the dielectric constant surrounding ion pairs strengthens them). The precipitate formed from high ethanol content mixture (vol% of ethanol > ~ 40%) can be dissolved in water to form a highly viscous polyelectrolyte coacervate, which shows potential applications in 3D printing under ethanol. In Chapter VII, electrophoretic deposition (EPD) was used to fabricate polyelectrolyte complex films, and it was shown to create thicker films than those created by the simple deposition of polyelectrolyte complexes in the absence of external electrical fields. A pulsed EPD with controlled pulse ON time and pulse OFF times can effectively suppress the formation of these bubbles. The mobility and zeta potential of BPEI/PAA complexes are modulated by the ratio of BPEI to PAA and pH of complexes, which will affect the thickness of deposited complex film. Regardless of different pulsed mode, by changing the electric field strength, the maximum thickness of BPEI/PAA complex film is obtained at a moderate electric field strength. High electric field strength will result in the dissolution of BPEI/PAA complexes due to formation of air bubbles and the high pH environment near the working electrode. In contrast, by using strong polyelectrolyte complex pair, PDAC/PSS, a proportional relationship between the thickness of complex film and electric field strength is observed. Therefore, the local pH change near working electrode is an important factor in the deposition of weak polyelectrolyte pairs. Moreover, ionic strength of the complex solution influences the charge density and stability of BPEI/PAA polyelectrolyte complexes. This work also shows the fabrication of polyelectrolyte complex-dye films using EPD. The loading of dye in complex films can be enhanced using proper EPD method.
Author: Martin Müller
Publisher: Springer
ISBN: 364240734X
Category : Technology & Engineering
Languages : en
Pages : 236
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Book Description
Advances in Polymer Science enjoys a longstanding tradition and good reputation in its community. Each volume is dedicated to a current topic, and each review critically surveys one aspect of that topic, to place it within the context of the volume. The volumes typically summarize the significant developments of the last 5 to 10 years and discuss them critically, presenting selected examples, explaining and illustrating the important principles, and bringing together many important references of primary literature. On that basis, future research directions in the area can be discussed. Advances in Polymer Science volumes thus are important references for every polymer scientist, as well as for other scientists interested in polymer science - as an introduction to a neighboring field, or as a compilation of detailed information for the specialist.
Author: National Institutes of Health (U.S.). Division of Research Grants
Publisher:
ISBN:
Category : Medicine
Languages : en
Pages : 1126
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Author: G. A. Johnson
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Jeff Allen Altig
Publisher:
ISBN:
Category :
Languages : en
Pages : 538
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Author: Nermin Acar
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Polyelectrolyte complexes, also called interpolymer complexes, are new class of chemically distinct and identifiable compounds. They are formed by polyelectrolytes that are macromolecules carrying a relatively large number of functional groups, orunder suitable conditions can become charged. Polyelectrolytes interact with various low and high molecular weight substances and form interpolymer complexes. These complexes are either separated from the solution as solids (polycomplex salt) or may settle as a polyelectrolyte complex gel, and they can be soluble in solution by controlling experimental factors. They are, in general, obtained in either case, by mixing polyelectrolytes solution, and by matrix polymerization. Significant differences might exist between the chemical, thermal and mechanical properties ofinterpolymer complexes with respect to their components and experimental conditions. All biological macromolecules, proteins, nucleic acids, and polysaccharides are polyelectrolytes and interact with each other and small ions during their biological function. Their electrostatic interactions contribute a significant part of the structural stabilization of biological molecules and they are major determinants for the kinetics of biological process. Considering all these vital processes research on the polyelectrolyte complexes obtained by synthetic polyelectrolytes might be a simple model system for the complicated biopolymer reactions. Studying the special properties of polycomplex formation between synthetic polyelectrolytes and low molecular weight compounds can be useful for understanding the nature of protein-lipid interaction in biomembranes or in the mechanism of protein denaturation. On the other hand, polyelectrolyte complexes are very promising materials for semi-permeable membranes for the industrial applications such as desalting of sea water, ultrafiltration and purification of aqueous solution and also for ultrafiltration of biological liquids.With all the above given respects, numerous studies have been made successively onvarious polyelectrolyte complexes in the last two decades. However very few studies have been reported on the interaction between some certain polyphosphates andvinylpyridine polymers. One of a few studies with poly(phosphate) has been given by N.Acar and T.Tulun on the interaction of poly(sodiumphosphate) (PSP) andpoly(4-vinylpyridiniumchloride) (P4VPHCl). The present study was aimed to investigate the interaction between poly(sodiumphosphate) and poly(4-vinylpyridiniumchloride) with 4-amino benzoic acid (low molecular weight compound) individually as well as the detailed continuation of the previous work which dealt with the polyelectrolyte complex formed by PSP and P4VPHCl.Poly(sodium phosphate) is interesting because it is an inorganic polymer and, rather unusually it is one of the few anionic polymers of the integral type. Actually polyphosphates are somewhat analogous to the nucleic acids. Vinylpyridine polymers have particular importance as polyelectrolytes and have great ability to develop interpolymer complexes with polyacids.The present study aims to form polyelectrolyte model complexes similar to or mimicking biologically active compounds and, thus, to understand the operating mechanism of biopolymers in living organisms through the investigation of the structure and various features of these model complexes. In the experimental part of the study, insoluble polyelectrolyte complexes were obtained from the both, concentrated and dilute solutions of PSP and P4VPHCl. Stoichiometry of the isolated complexes were found to be 1:1 as a result of analysis of the supernatant liquid in conjunction with concentration of the initial components.In the dilute aqueous solution, occurrence of polyelectrolyte complex was proved by UV spectroscopy. Salt effect of NaCl, the effect of NaCl on complex formation andthermal properties of complexes were investigated.Regarding the reaction of PSP with 4-amino benzoic acid, hydrochloride (PABCl),the stoichiometry of complex was found as 1:1.2 using viscometric and volumetricanalysis of the supernatant. Besides, spectroscopic and conductometric methods were used for the complex stoichiometry. The experimental factors such as pH,ionic strength and temperature that affect the stoichiometry of complex were investigated.In the case of the poly(4-vinylpyridine) (P4VP) with 4-aminobenzoic acid, IR spectroscopy , potentiometry and DSC were used and the nature of binding between the components was identified as hydrogen bonding.It is known that transition metals take part in the biochemical process. In the present study, interaction of copper (II) with P4VP- PABA complex system is of interest. Potentiometric method was used to follow the above stated interaction in aqueousethanol solution for P4VP-PABA system. Protonation and the stability constants ofP4VP-PABA system were determined.Swelling properties of polyelectrolyte systems have been studied largely due to their industrial uses. In order to investigate the swelling properties of P4VPHCl-PSP system, PSP and P4VP that is the initial component of polycation were subjected to irradiation for six different radiation doses to obtain cross linked structure. It is found that radiation has no affect on PSP.After irradiation the insoluble, the gel, parts were determined by soxhlet extraction and UV spectroscopy. Up to certain dose the gelpercent of P4VP samples increased, and thereafter remained unchanged. From the relation between gel fraction and radiation dose, the efficiency of crosslinking and of scission were determined. Irradiated P4VP that contained only gel part was quaternized to obtain waterswellable P4VPHCl gel. The interaction of P4VPHCl gel with the aqueous solution of PSP was investigated considering ionic strength and pH.
Author: Frank Karasz
Publisher: Springer
ISBN: 9780306305818
Category : Technology & Engineering
Languages : en
Pages : 374
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Book Description
The study of the electrical properties of polymers constitutes a substantial fraction of the total research interest in macro molecular behavior. Because of the increasing attention now being paid to theoretical and experimental aspects of the phenomena encountered, a symposium focusing particularly on dielectric behavior was held at the l6lst National Meeting of the American Chemical Society in Los Angeles, California, March, 1971. The authoritative papers in this volume were all presented at this symposium, which was sponsored by the Polymer Division of the American Chemical Society. An obvious advantage of such a collection is that it keep~ together closely related material which would otherwise tend to be dispersed amongst different journals; a further factor of which most authors represented here have taken advantage is that it gives an opportunity to present research in less attenuated form than is now normally possible in journals. I wish to thank all the authors for their uniformly excellent contributions and for their cooperation in the publication of this volume. Thanks are also due to Dr. S. Matsuoka for chairing one of the sessions at the symposium. September, 1971 Frank E. Karasz v LIST OF CONTRIBUTORS B. Baysal, Department of Chemistry, Dartmouth College, Hanover, New Hampshire Richard H. Boyd, Department of Chemical Engineering and Division of Materials Science and Engineering, University of Utah, Salt Lake City, Utah M. G. Broadhurst, Institute for Materials Research, National Bureau of Standards, Washington, D. C.
Author: Sarkyt E. Kudaibergenov
Publisher: Springer Science & Business Media
ISBN: 9780306467813
Category : Science
Languages : en
Pages : 232
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Book Description
This book comprehensively reviews the synthesis, characterization and application aspects of linear and crosslinked synthetic polyampholytes - simple model of biopolymers - starting from the 1950's. The synthetic strategy of "annealed", "quenched" and "zwitterionic" polyampholytes, the properties of polyampholytes in solutions and in gel state are considered. The complexation ability of polyampholytes with respect to transition metal ions, ionic surfactants, dyes and organic probes polyelectrolytes, proteins and colloid particles is discussed. Stimuli-sensitive behavior of various amphoteric gel and membrane systems demonstrating rhythmically phenomenon similar to that of heart beat, deformation, oscillation or self-oscillation phenomena stimulated by temperature, pH and electric field are illustrated. Catalytic properties of synthetic polyampholytes simulating the function of enzymes are also considered.
