Download or read book Modeling Polymer colloid Phase Behavior written by Naa Larteokor Quarcoo and published by . This book was released on 2007 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: Here, we investigate the phase behavior of silica colloids in solution with two uncharged polymers, polyethylene oxide (PEO) and polyvinylpyrrolidone (PVP), with the values of Rg/R = 0.7 and 1.8 for each polymer. The four observed phase boundaries are related to the polymer characteristics of Rg and entanglement concentration (c*). The polymer properties were characterized by viscometry, light scattering and size exclusion chromatography. The experimental observations suggest that phase separation depends on the ratio of the polymer concentration to the entanglement concentration for a given polymer.
Download or read book A Mechanistic Understanding of the Polymer induced Phase Behavior of Colloidal scale Suspensions written by Naa Larteokor McFarlane and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The phase behavior of model polymer - colloid mixtures is measured in the "protein limit", i.e., when the radius of gyration of the polymer (R g) is greater than or approximately equal to the radius of the colloid (R) and in the "colloid limit" (R> R g). In this work, alumina-covered silica nanoparticles are mixed with poly (ethylene oxide) (PEO) or poly (vinyl pyrolidone) (PVP) at asymmetry ratios of R g /R = 0.7 and 1.8. The adsorption of the two polymers onto the cationic nanoparticles was measured using isothermal titration calorimetry (ITC), gravimetric methods, and dynamic light scattering. Addition of PEO to stable nanoparticle dispersions leads to phase separation by depletion flocculation in both deionized water and buffer solutions. The phase separation mechanism for the PVP - nanoparticle system depends on the suspension medium. In water, bridging induced separation occurs below the saturation adsorption of PVP; above surface saturation, mixing leads to depletion-induced separation. In acidic buffer, phase separation results from depletion-induced interactions. ITC measurements of the heats of adsorption unambiguously determine the effects of polymer type and added buffer solution on the stability of nanoparticle dispersions upon the addition of adsorbing polymer. We find weak segmental adsorption energies of ~0.2 k B T for PEO in water and buffer, consistent with the observed phase separation. For PVP in water, segmental adsorption energies of order ~1.6 k B T support bridging flocculation in water, whereas a weaker adsorption energy of ~0.7 k B T in buffer is consistent with a lack of significant bridging flocculation. The difference between bridging and depletion is distinguished by visual appearance, rheological measurements, and small-angle neutron scattering (SANS). SANS measurements of PVP phase separated samples show a loss of the fractal region at low wavevector with increasing polymer concentration in moving from bridge flocculated to the depletion phase separation regime. There was also a concurrent shift in the interaction peak to lower Q values. These two effects signify a decrease in the density of the fractal aggregates with changing phase separation mechanism, consistent with a shift from bridging flocculation to depletion attraction. The ratio of polymer concentration to polymer entanglement concentration (c/c*) required to induce phase separation increases with increasing R g /R in agreement with theoretical predictions of the polymer reference interaction site model (PRISM). This trend opposes classical depletion theories because the classical theories do not account for polymer entanglement, amongst others, by assuming non-interacting polymers that interact as hard spheres. This assumption is clearly violated when R g> R when the nanoparticles can interpenetrate the polymer coils. Cationic nanovesicles are formed by sonication and characterized by viscometry, dynamic light scattering, and small-angle neutron scattering. The phase behavior of PVP - nanovesicle mixtures are measured and compared to the cationic nanoparticle system. Unlike the colloids, the nanovesicles do not phase separate on a short time scale, but rather, become unstable and revert back to the birefringent lamellae structure due to electrostatic repulsion of the charged heard groups. The rate of this coalescence is enhanced by the addition of polymer. This work provides a complete data set exploring bridging flocculation and depletion induced phase separation in the protein limit. As such it can be used to test theoretical work and to provide guidance in formulating polymer - nanoparticle mixtures. Extension to systems of nanovesicles highlights the differences inherent in selfassembled systems as compared to nanoparticles. The results can help guide industrial formulations containing mixtures of polymer, nanoparticles, and surfactant mesophases.
Download or read book Using Molecular Simulation to Explore Protein and Colloidal Phase Behavior in Bulk Confinement and Mixtures written by Thomas W. Rosch and published by . This book was released on 2008 with total page 149 pages. Available in PDF, EPUB and Kindle. Book excerpt: Because of the ubiquity of colloidal solutions in everyday industrial applications such as papermaking and coatings there is a need to be able to efficiently design and manufacture these substances. A related issue concerns the connection between many physiological diseases and heath defects and the stability and phase behavior of certain proteins. It is imperative to understand the physical mechanisms that cause proteins to change their normal solution characteristics. To design colloidal solutions for specific applications as well as to produce preventative medicines and therapies an intimate knowledge of the connection between particle interactions and overall physical properties of the solution is needed. To probe this issue four types of systems are examined. In each system solution conditions are altered affecting the nature and strength of the particle interactions. Our goal is to understand the physics behind the evolution of fluid properties that occurs because of changes in microscopic interactions. The method we employ in this pursuit is grand canonical transition matrix Monte Carlo. We examine an embedded point charge protein model of lysozyme in bulk, mixed with polymer, as well as in confinement. We find that in bulk the model is able to capture qualitatively experimental trends for changes in critical temperature and evolution of the fluid phase diagram with changing solution conditions such as salt concentration and pH. Quantitatively the model predicts a relatively narrow coexistence curve compared to experimental values. It is found that the osmotic second virial coefficient remains relatively constant over a broad range of solutions conditions suggesting a universal magnitude of attraction needed to induce phase separation. We examine a simple system consisting of hard sphere colloids with added Gaussian core polymers. Decreasing the size of the polymers relative to colloids as well as increasing the energetic repulsion between polymers upon overlap results in an overall stabilization of the mixture. Unlike bulk solutions containing molecules of the Carlsson et al. lysozyme model, the osmotic second virial coefficient at the critical point for model colloid-polymer mixtures is not constant but depends on polymer size and interaction. Increasing polymer size or decreasing polymer repulsion results in a larger negative value. Overall the model fails to capture the experimental behavior of polymer excluded volume interactions because its inability to describe the polymers capability of deformation around the colloid. We extend our analysis to a mixture containing the embedded charge model for lysozyme and Gaussian core polymers. Overall, the system exhibited a strong dependence on pH and salt concentration that qualitatively followed experimental trends. Increase of salt concentration or decrease in protein charge decreases the number of polymers needed to induce phase separation. This trend was not sensitive to the size of the polymer relative to the protein. Finally we examine the effect surface interactions have on the phase behavior for the lysozyme model as well as a simple square well model. Both systems exhibited a distinctly non-monotonic variation of its critical temperature as a function of fluid-wall interaction strength. A maximum occurs at an intermediate strength. We introduce two metrics that enable one to predict the location of this maximum. The first is related to the contact angle a fluid makes with the confining substrate while the second is based upon virial coefficient information. Because similar trends are exhibited in both systems we believe that the results should be general in nature.
Download or read book Polymers Liquids And Colloids In Electric Fields Interfacial Instabilites Orientation And Phase Transitions written by Yoav Tsori and published by World Scientific. This book was released on 2009-02-25 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt: This unique book aims to expose the reader to a wide range of phenomena occurring when soft matter systems are put under the influence of an external electric field. The book shows how an electric field can be used to affect objects at the submicron scale, and how it controls the phase behavior of liquids and polymers. The main focus is on the basic underlying mechanisms. Some technological applications are dealt with as well.Book chapters are arranged in a logical order, from “simple” systems to more complicated ones. In addition, each topic is covered by the mixed bag of theory, experiment and simulation; and this will give the reader a broad perspective of the underlying physical phenomena.
Download or read book Polymer Mediated Phase Stability of Colloids written by Álvaro González García and published by Springer Nature. This book was released on 2019-10-28 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt: Colloid–polymer mixtures are subject of intensive research due to their wide range of applicability, for instance in coatings and food-stuffs. This thesis constitutes a fundamental investigation towards a better control over the stability of such suspensions. Through the chapters, different key parameters governing the stability of colloid–polymer mixtures are explored. How the colloid (pigment) shape and the effective polymer-colloid affinity modulate the stability of the suspension are examples of these key parameters. Despise the mostly theoretical results presented, the thesis is written in a format accessible to a broad scientific audience. Some of the equations of state presented might of direct use to experimentalists. Furthermore, new theoretical insights about colloid–polymer mixtures are put forward. These include four-phase coexistences in effective two-component, quantification of depletant partitioning at high colloidal concentrations, multiple re-entrant phase behaviour of the colloidal fluid–solid coexistence, and a condition where polymers are neither depleted nor adsorbed from/to the colloidal surface.
Download or read book Polymers Liquids and Colloids in Electric Fields written by Yoav Tsori and published by World Scientific. This book was released on 2009 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt: This unique book aims to expose the reader to a wide range of phenomena occurring when soft matter systems are put under the influence of an external electric field. The book shows how an electric field can be used to affect objects at the submicron scale, and how it controls the phase behavior of liquids and polymers. The main focus is on the basic underlying mechanisms. Some technological applications are dealt with as well. Book chapters are arranged in a logical order, from OC simpleOCO systems to more complicated ones. In addition, each topic is covered by the mixed bag of theory, experiment and simulation; and this will give the reader a broad perspective of the underlying physical phenomena."
Download or read book Colloids and the Depletion Interaction written by Henk N. W. Lekkerkerker and published by Springer Nature. This book was released on with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Colloids and the Depletion Interaction written by Henk N.W. Lekkerkerker and published by Springer Science & Business Media. This book was released on 2011-05-12 with total page 245 pages. Available in PDF, EPUB and Kindle. Book excerpt: Colloids are submicron particles that are ubiquitous in nature (milk, clay, blood) and industrial products (paints, drilling fluids, food). In recent decades it has become clear that adding depletants such as polymers or small colloids to colloidal dispersions allows one to tune the interactions between the colloids and in this way control the stability, structure and rheological properties of colloidal dispersions. This book offers a concise introduction to the fundamentals of depletion effects and their influence on the phase behavior of colloidal dispersions. Throughout the book, conceptual explanations are accompanied by experimental and computer simulation results. From the review by Kurt Binder: "They have succeeded in writing a monograph that is a very well balanced compromise between a very pedagogic introduction, suitable for students and other newcomers, and reviews of the advanced research trends in the field. Thus each chapter contains many and up to date references, but in the initial sections of the chapters, there are suggested exercises which will help the interested reader to recapitulate the main points of the treatment and to deepen his understanding of the subject. Only elementary knowledge of statistical thermodynamics is needed as a background for understanding the derivations presented in this book; thus this text is suitable also for advanced teaching purposes, useful of courses which deal with the physics for soft condensed matter. There does not yet exist any other book with a similar scope..... The readability of this book is furthermore enhanced by a list of symbols, and index of keywords, and last not least by a large number of figures, including many pedagogic sketches which were specifically prepared for this book. Thus, this book promises to be very useful for students and related applied sciences alike." Eur. Phys. J. E (2015) 38: 73
Download or read book Depletion Effects and Phase Behavior in Model Mixtures of Rod like Polymers and Colloidal Spheres written by Yeng-Long Chen and published by . This book was released on 2001 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Phase Behaviour of Proteins and Colloid Polymer Mixtures written by Christoph Gögelein and published by Forschungszentrum Jülich. This book was released on 2008 with total page 165 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Phase Behavior and Effective Interactions in Colloidal Suspensions written by and published by Cuvillier Verlag. This book was released on 2007-04-25 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: Colloidal suspensions describe particles with size from typically a few nanometers to a few microns which are dispersed in a medium. In physics, in chemistry, and in biology colloids play an important role and the study of colloidal systems underwent a recent renaissance. This is based on the development of experimental techniques, the availability of extensive computer simulations and well-developed theoretical approaches. From a technological point of view, the relevance of micro- and nanostructured materials and the presence of colloids in nature and everyday life motivates study of this rich field. In this thesis the phase behavior and the effective interactions of colloidal suspensions in bulk, in contact with surfaces, and in confined geometry are studied. For mixtures of particles with hard-core interactions the model introduced by Asakura, Oosawa and Vrij provides an appropriate starting-point. Based on that model the free-volume theory and the density functional theory are employed. In experimental systems one faces particles with properties such as the size or the shape which are described by a distribution. To capture that issue a generalized approach based on free-volume theory for treating mixtures of colloids and a polydisperse depletion agent is presented. Within that approach it is possible to treat size and morphology polydispersity. A depletion agent with a bimodal distribution possessing two length scales can be studied. Though the Asakura-Oosawa-Vrij model describes a simple fluid - a mixture of hard spheres and ideal polymer - the phenomenology is rather rich: in contact with a wall one finds layering and wetting effects and in confined geometry of a narrow pore one finds capillary condensation. The competition between both effects manifests itself in thermodynamic properties like the excess colloid adsorption and the solvation force between the two confining walls. Solvent phase separation complicates the evaluation of interparticle interactions between the solute particles. We address this question for the wall-colloid and the colloid-colloid geometry. For a non-spherical particle the effect of curvature on thermodynamic quantities is studied.
Download or read book Trends in Colloid and Interface Science XIV written by Vitaly Buckin and published by Springer. This book was released on 2003-07-01 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 13th Conference of the European Colloid and Interface Society (ECIS 99) was held in September 1999 in Dublin, Ireland. It brought together scientists from academic research and industry within the field of physics and chemistry of colloids and interfaces. The Conference focused on the following topics: - Surfactant colloids; - Polymer colloids and solid particles; - Food colloids; - Soft matter interfaces; - Biosystems; - Rheology; - Experimental methods in colloid and interface science.
Download or read book Phase Behavior Microstructure and Mechanics of Colloid Polymer Mixtures written by Syed Ali Shah and published by . This book was released on 2003 with total page 516 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Polymer Colloids written by Rodney Priestley and published by Royal Society of Chemistry. This book was released on 2019-12-02 with total page 442 pages. Available in PDF, EPUB and Kindle. Book excerpt: Academic and industrial research around polymer-based colloids is huge, driven both by the development of mature technologies, e.g. latexes for coatings, as well as the advancement of new materials and applications, such as building blocks for 2D/3D structures and medicine. Edited by two world-renowned leaders in polymer science and engineering, this is a fundamental text for the field. Based on a specialised course by the editors, this book provides the reader with an invaluable single source of reference. The first section describes formation, explaining basic properties of emulsions and dispersion polymerization, microfluidic approaches to produce polymer-based colloids and formation via directed self-assembly. The next section details characterisation methodologies from microscopy and small angle scattering, to surface science and simulations. The final chapters close with applications, including Pickering emulsions and molecular engineering for materials development. A comprehensive guide to polymer colloids, with contributions by leaders in their respective areas, this book is a must-have for researchers and practitioners working across polymers, soft matter and chemical and molecular engineering.
Download or read book Colloidal Dispersions written by William Bailey Russel and published by Cambridge University Press. This book was released on 1991 with total page 548 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers the physical side of colloidal science from the individual forces acting between particles smaller than a micrometer that are suspended in a liquid, through the resulting equilibrium and dynamic properties. A variety of internal forces both attractive and repulsive act in conjunction with Brownian motion and the balance between them all decides the phase behaviour. On top of this various external fields, such as gravity or electromagnetic fields, diffusion and non-Newtonian rheology produce complex effects, each of which is of important scientific and technological interest. The authors aim to impart a sound, quantitative understanding based on fundamental theory and experiments with well-characterised model systems. This broad grasp of the fundamentals lends insight and helps to develop the intuitive sense needed to isolate essential features of the technological problems and design critical experiments. The main prerequisites for understanding the book are basic fluid mechanics, statistical mechanics and electromagnetism, though self contained reviews of each subject are provided at appropriate points. Some facility with differential equations is also necessary. Exercises are included at the end of each chapter, making the work suitable as a textbook for graduate courses in chemical engineering or applied mathematics. It will also be useful as a reference for individuals in academia or industry undertaking research in colloid science.
Download or read book An Introduction to Polymer Colloids written by Françoise Candau and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: The growth of interest in the subject of Polymer Colloids over the last twenty five years or so has been very large resulting now in major international conferences on an annual basis and many national ones as well. The interest stems not only from the wide range of applications of these materials but also from a curiosity as to the mechanism of formation and their growing use as model particles to investigate fundamental aspects of physics and chemistry. In July 1988 a NATO Advanced Study Institute was held in Strasbourg, France, at the Centre St. Thomas. As an educational introduction to this I nstitute a series of eight lectures was given to cover the fundamental aspects of the subject. These eight lectures have now been compiled into an Introductory Text covering, emulsion poly merization, dispersion polymerization, inverse emulsion polymerization, the morphology of copolymer latices, the colloidal properties of latices, characterization methods and rheology. It is hoped that these will serve a wide audience, undergraduates, graduate-students and research workers, both in industry and academe. The chapters all contain review material up to date at the time of publication. fhe 1988 NATO Advanced Study I nstitute was made possible by a grant from the NATO-AS I programme and the following companies: BASF, Ludwigshafen, West Germany The Dow Chemical Company, Michigan, USA Dow Chemical Rheinwerk GmbH, Rheinmunster, West Germany ICI PLC, Runcorn, England S. C. Johnson and Son Inc., Racine, USA NORSOLOR, Verneuil en Halatte, France Rhone Poulenc, Aubervilliers, France.
Download or read book Phase Behavior of Polymer Blends written by Karl Freed and published by Springer Science & Business Media. This book was released on 2005-09-01 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt:
