Download or read book Structure and Properties of Ordered Block Copolymer Membranes written by Mark Irl Ostler and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Block Copolymers written by Douglas Russell Greer and published by . This book was released on 2017 with total page 67 pages. Available in PDF, EPUB and Kindle. Book excerpt: Block copolymer (BCP) self-assembly has garnered significant attention for several decades because it can yield ordered structures in a wide range of morphologies with potential or practical applications in many fields. A diblock copolymer is a polymer consisting of two distinct monomers. The monomers are arranged such that there are distinct chains of each monomer, and the chains are covalently linked together to form a single copolymer chain. In BCPs, the enthalpic contributions to free energy are often significant enough overcome entropy, resulting in the formation of microdomains of each type of monomer. This self-assembly is useful for fundamental studies of molecular conformation and for engineering materials wherein the useful properties of two chemically distinct chains are incorporated into a single molecule. In this work we will demonstrate the extraordinary effectiveness block copolymers to both types of studies. In this dissertation work, we used peptoid diblock copolymers to identify a motif common to all bulk phase crystalline peptoid polymers. Poly N-substituted glycine materials (peptoids) have the capacity for prolific diversity due to their large library of monomers, synthetic sequence control, and monodispersity. These properties make peptoids an ideal material for the study of the relationship between chemical structure and supramolecular structure. In order to probe this relationship, we synthesized and analyzed a series of crystalline peptoid copolymers, systematically varying peptoid side-chain length (S) and main-chain length (N). In all peptoids, we found that the three unit cell dimensions - a, b, and c - are simple linear functions of S and N. These relationships indicate that the molecules adopt extended, planar conformations. This new structural motif can be used to design broad classes of assemblies which have specific unit cell sizes, functional group densities, or aqueous monolayer thicknesses, based upon a specific backbone conformation and packing preference. Furthermore, these materials ordered well enough in water to achieve the first 2 Å level transmission electron microscopy of a synthetic polymer. In the second study, we used block copolymers to impart two properties in a material effective for the pervaporation – a separation consisting of permeation and evaporation – of aqueous volatile organic compounds (VOCs). We performed this separation using a microphase separated polystyrene-block-polydimethylsiloxane-block-polystyrene (SDS) copolymer membrane. The PDMS domains are rubbery and have good permeation properties for volatile organic compounds (VOCs). The PS domains are glassy and provide the membrane with structural integrity. We find that using SDS block copolymer membranes is effective for the removal of inhibitors from lignocellulosic dilute-acid hydrolysate. Furthermore, the pervaporation-treated hydrolysates are suitable for ethanol fermentation with Saccharomyces cerevisiae . These results indicate that block copolymer-based pervaporation is a viable approach for hydrolysate detoxification in an industrial bioethanol production process. Taken together, these studies demonstrate that block copolymers are an effective tool with which to implement both fundamental molecular engineering studies and chemical engineering design.

Download or read book Processing Structure and Properties of Block Copolymers written by M.J. Folkes and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 219 pages. Available in PDF, EPUB and Kindle. Book excerpt: Block copolymers represent an important class of multi-phase material, which have received very widespread attention, particularly since their successful commercial development in the mid-1960s. Much of the interest in these polymers has arisen because of their rather remarkable micro phase morphology and, hence, they have been the subject of extensive microstructural examination. In many respects, the quest for a comprehensive interpretation of their structure, both theoretically and experimentally, has not been generally matched by a corresponding enthusiasm for developing structure/property relationships in the context of their commercial application. Indeed, it has been left largely to the industrial companies involved in the development and utilization of these materials to fulfil this latter role. While it is generally disappointing that a much greater synergism does not exist between science and technology, it is especially sad in the case of block copolymers. Thus these materials offer an almost unique opportunity for the application of fundamental structural and property data to the interpretation of the properties of generally processed artefacts. Accordingly, in this book, the editor has drawn together an eminent group of research workers, with the specific intention of highlighting some of those aspects of the science and technology of block copolymers that are potentially important if further advances are to be made either in material formulation or utilization. For example, special consideration is given to the relationship between the flow properties of block copo lymers and their microstructure.

Download or read book Structure property processing Relations in Sulfonated Block Copolymer Membranes written by Phuc Vinh Truong and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Ionic block copolymers combine the functionality of ionomers with the mechanical properties of thermoplastics, and are widely studied for applications in water purification and electrochemical devices. Membranes (thin films) are often prepared by solution casting. As the solvent evaporates, the strong incompatibility between ionic and non-ionic segments will trap non-equilibrium structures in the film. Consequently, the equilibrium block copolymer phase diagrams are poor predictors of membrane morphology, making it difficult to engineer the optimal domain sizes and transport pathways. The objective of this dissertation is to establish structure-property- processing relations of sulfonated pentablock copolymer (SPC) membranes. Films were prepared by casting from solvents of varying polarity, as the choice of solvent controls the solution state structure, and were characterized with complementary measurements that include X-ray scattering, microscopy, infrared spectroscopy, water uptake, impedance spectroscopy and tensile tests. First, we investigate the structure and transport properties of lamellar SPC membranes. All films were cast from mixtures of toluene and n-propanol. As the polarity of the casting solvent increases, the bulk structure becomes more disordered with a higher defect density, and the surface becomes more hydrophilic. These structural changes lead to enhancements in water uptake and proton conductivity. The onset of structural disorder coincides with a change in solvent selectivity towards the sulfonated domains. Therefore, the sulfonated block becomes more swollen during processing, which may induce defects that connect the neighboring sulfonated domains and produce a continuous structure. Next, we investigate the effects of hydration cycles on the structure and performance of commercial SPC films, which is relevant when evaluating their potential as water purification membranes or proton-conducting layers. We find that hydration cycling drives a structural transition from isolated micelles with a sulfonated core to a network of percolating sulfonated domains, which is beneficial for transport. However, hydration cycling can also induce mechanical instabilities that reduce swelling, water uptake and ductility. Consequently, transport properties are governed by the tradeoff between nanoscale restructuring and macroscale buckling. Significantly, we believe that our methodology and findings will be useful for design, optimization, and fundamental investigations of other ionic block or random polymer systems.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ion Transport in Nanostructured Block Copolymer Ionic Liquid Membranes written by Megan Lane Hoarfrost and published by . This book was released on 2012 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt: Incorporating an ionic liquid into one block copolymer microphase provides a platform for combining the outstanding electrochemical properties of ionic liquids with a number of favorable attributes provided by block copolymers. In particular, block copolymers thermodynamically self-assemble into well-ordered nanostructures, which can be engineered to provide a durable mechanical scaffold and template the ionic liquid into continuous ion-conducting nanochannels. Understanding how the addition of an ionic liquid affects the thermodynamic self-assembly of block copolymers, and how the confinement of ionic liquids to block copolymer nanodomains affects their ion-conducting properties is essential for predictable structure-property control. The lyotropic phase behavior of block copolymer/ionic liquid mixtures is shown to be reminiscent of mixtures of block copolymers with selective molecular solvents. A variety of ordered microstructures corresponding to lamellae, hexagonally close-packed cylinders, body-centered cubic, and face-centered cubic oriented micelles are observed in a model system composed of mixtures of imidazolium bis(trifluoromethylsulfonyl)imide ([Im][TFSI]) and poly(styrene-b-2-vinyl pyridine) (PS-b-P2VP). In contrast to block copolymer/molecular solvent mixtures, the interfacial area occupied by each PS-b-P2VP chain decreases upon the addition of [Im][TFSI], indicating a considerable increase in the effective segregation strength of the PS-b-P2VP copolymer with ionic liquid addition. The relationship between membrane structure and ionic conductivity is illuminated through the development of scaling relationships that describe the ionic conductivity of block copolymer/ionic liquid mixtures as a function of membrane composition and temperature. It is shown that the dominant variable influencing conductivity is the overall volume fraction of ionic liquid in the mixture, which means there is incredible freedom in designing the block copolymer architecture in order to optimize the mechanical and other properties of the membrane without sacrificing conductivity. The derived scaling relationships are shown to be general for many block copolymer and ionic liquid chemistries. In certain cases, the mechanism of ion conduction in the ionic liquid is affected by block copolymer nanoconfinement. The introduction of excess neutral imidazole to [Im][TFSI] leads to enhanced proton conductivity as well as a high H+ transference number due to facilitated proton hopping between imidazole molecules. We show that there is increased proton hopping when the nonstoichiometric ionic liquid is confined to lamellar block copolymer nanodomains, which we hypothesize is due to changes in the hydrogen bond structure of the ionic liquid under confinement. This, in combination with unique ion aggregation behavior, leads to a lower activation energy for macroscopic ion transport compared to that in a corresponding homopolymer/ionic liquid mixture. Through this work, we further the understanding of the relationship between membrane composition, structure, and ion transport. The findings presented herein portend the rational design of nanostructured membranes having improved mechanical properties and conductivity.

Download or read book Multiphase Biomedical Materials written by T. Tsuruta and published by CRC Press. This book was released on 2021-12-17 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: Following many reports that were published in the last two decades on correlations of multiphase structures of the surface of materials with their antithrombogenicity or biocompatibility a research project ''Design of Multiphase Biomedical Materials'' was carried out in Japan between 1982 and 1986. The objective of this research project was to elucidate various aspects of biomedical behaviour of multiphase systems at the interface with living bodies at the molecular, cellular and tissue levels. Multiphase materials studied cover polymers having microphase-separated structures, hydrogels, immobilized enzymes (or cells), ceramics and metallic materials. The research project was carried out by the following subgroups: -- Multiphase biomedical materials with microdomain structures -- Multiphase biomedical materials containing liquid components -- Hybrid-type multiphase biomedical materials with biological components -- Inorganic and metallic multiphase biomedical materials -- Methods for analysis and evaluation of multiphase biomedical materials This book contains the results of the research project in an edited form and aims to provoke a better understanding about various aspects of cell--material interactions in which the multiphase systems play a crucial role.

Download or read book Advanced Materials for Membrane Preparation written by Maria Giovanna Buonomenna and published by Bentham Science Publishers. This book was released on 2012 with total page 303 pages. Available in PDF, EPUB and Kindle. Book excerpt: The need to reduce pollution and the waste of energy and resources imposes a wider diffusion of environmentally friendly membrane systems. The expanding domain of membrane operations demands tailored materials with unprecedented performances and resistanc

Download or read book Nanofiltration 2 Volume Set written by Andrea Iris Schäfer and published by John Wiley & Sons. This book was released on 2021-08-09 with total page 1267 pages. Available in PDF, EPUB and Kindle. Book excerpt: An updated guide to the growing field of nanofiltration including fundamental principles, important industrial applications as well as novel materials With contributions from an international panel of experts, the revised second edition of Nanofiltration contains a comprehensive overview of this growing field. The book covers the basic principles of nanofiltration including the design and characterizations of nanofiltration membranes. The expert contributors highlight the broad ranges of industrial applications including water treatment, food, pulp and paper, and textiles. The book explores photocatalytic nanofiltration reactors, organic solvent nanofiltration, as well as nanofiltration in metal and acid recovery. In addition, information on the most recent developments in the field are examined including nanofiltration retentate treatment and renewable energy-powered nanofiltration. The authors also consider the future of nanofiltration materials such as carbon- as well as polymer-based materials. This important book: Explores the fast growing field of the membrane process of nanofiltration Examines the rapidly expanding industrial sector's use of membranes for water purification Covers the most important industrial applications with a strong focus on water treatment Contains a section on new membrane materials, including carbon-based and polymer-based materials, as well as information on artificial ion and water channels as biomimetic membranes Written for scientists and engineers in the fields of chemistry, environment, food and materials, the second edition of Nanofiltration provides a comprehensive overview of the field, outlines the principles of the technology, explores the industrial applications, and discusses new materials.

Download or read book Studies of Block Copolymer Thin Films and Mixtures with an Ionic Liquid written by Justin Virgili and published by . This book was released on 2009 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: Block copolymers are capable of self-assembling into structures on the 10-100 nm length scale. Structures of this size are attractive for applications such as nanopatterning and electrochemical membrane materials. However, block copolymer self-assembly in these examples is complicated by the presence of surfaces in the case of thin films and the presence of an additive, such as an ionic liquid, in the case of electrochemical membrane materials. Improved understanding of the structure and thermodynamics of such systems is necessary for the development of structure-property relationships in applications for block copolymers, such as nanopatterning and electrochemical devices. To address the challenge of block copolymer thin film characterization over large areas, resonant soft X-ray scattering (RSoXS) has been applied to characterize order formation in copolymer thin films. Using theory and experiment, the dramatic chemical sensitivity of RSoXS to subtle differences in the bonding energies of different blocks of a copolymer is demonstrated. The unambiguous identification of structure and domain size in block copolymer thin films using RSoXS enables a quantitative comparison of the bulk block copolymer structure and domain size, leading to improved understanding of the impact of surfaces on block copolymer self-assembly. The self-assembly of block copolymer/ionic liquid mixtures has been characterized as a function of block copolymer composition and molecular weight, mixture composition, and temperature using small-angle X-ray scattering (SAXS), optical transmission characterization, wide-angle X-ray scattering (WAXS), and differential scanning calorimetry (DSC). The resulting phase behavior is reminiscent to that of block copolymer mixtures with a selective molecular solvent and lamellar, cylindrical, ordered spherical micelles, and disordered phases are observed. Analysis of order-disorder transitions and molecular weight scaling analysis qualitatively indicates that the segregation strength between block copolymer phases increases with ionic liquid loading. DSC characterization of the thermal properties of the block copolymer/ionic liquid mixtures reveals two composition dependent regimes. At high block copolymer concentrations, a "salt-like" regime corresponding to an increase in the block copolymer glass transition temperature is observed, while at intermediate block copolymer concentrations, a "solvent-like" regime corresponding to a decrease in the block copolymer glass transition temperature is observed. The distribution of ionic liquid within microphase-separated domains of a block copolymer has been characterized using contrast matched small-angle neutron scattering (SANS) and DSC. The ionic liquid is shown to partition selectively into domains formed by one block of a block copolymer in agreement with studies of the phase behavior of ionic liquid/block copolymer mixtures. Unexpected differences in ionic liquid partitioning are observed in mixtures containing a deuterated versus hydrogenated ionic liquid.

Download or read book Porous Polymers written by Michael S. Silverstein and published by John Wiley & Sons. This book was released on 2011-04-19 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gathers the various aspects of the porous polymer field into one volume. It not only presents a fundamental description of the field, but also describes the state of the art for such materials and provides a glimpse into the future. Emphasizing a different aspect of the ongoing research and development in porous polymers, the book is divided into three sections: Synthesis, Characterization, and Applications. The first part of each chapter presents the basic scientific and engineering principles underlying the topic, while the second part presents the state of the art results based on those principles. In this fashion, the book connects and integrates topics from seemingly disparate fields, each of which embodies different aspects inherent in the diverse field of porous polymeric materials.

Download or read book Morphology Development of Block Copolymer and Homopolymer Blend Films written by Yuxuan Chen and published by . This book was released on 2015 with total page 37 pages. Available in PDF, EPUB and Kindle. Book excerpt: Block copolymers (BCPs) have received considerable attention, as they can self-assemble into different nanoscale structures with different properties under certain conditions for a variety of applications. For example, cylinder forming block copolymers can be applied as effective nano-filtration membranes for oil-water separation. The main objective of this work is to investigate the morphological development of block polymer and homopolymer blend systems that can be ultimately useful in applications. Poly (styrene-block-2vinyl pyridine) (PS-b-P2VP) was blended with varying concentrations from 0-40 wt% homopolymer poly2-vinylpyridine (P2VP) to examine its effect on morphology, domain size and orientation in thin films. We observed morphologies ranging from parallel cylinders to quasi-micellar cylinders. The effect of different annealing methods (oven annealing, CZA-S and direct immersion annealing) was studied. In uniform thermal annealing, the orientation of P2VP cylinders, changes from parallel to perpendicular and back to parallel again as the homopolymer mass fraction increases in blend and then ultimately results in formation of micelles. Similar results were obtained with zone annealing, however the degree of ordering was higher and faster. For direct immersion annealing, the morphology changes from perpendicular to the mixed morphology composing of parallel and perpendicular orientations, which reflects the degree of isotropy provided by the solvent mixture that reduces the bias provided by the substrate interactions to orient cylinders horizontally to substrate. The opportunity to introduce homopolymer into ordered block copolymer domains in selective manner is useful since this allows us to tune the film morphology without synthesizing new block copolymers for varying molecular weights to obtain similar effects. Extraction of the homopolymer by selective solvent after ordering allows us to make nanoporous channels for membrane applications.

Download or read book Polymer Membranes written by T. deV. Naylor and published by iSmithers Rapra Publishing. This book was released on 1996 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes the constitution and application of polymeric membranes in separation processes. The separation processes covered are reverse osmosis and nanofiltration, ultrafiltration, gas separation, pervaporation and ion exchange. An additional indexed section containing several hundred abstracts from the Rapra Polymer Library database provides useful references for further reading.

Download or read book Block Copolymer Pervaporation Membranes for Biofuel Separation written by Chae-young Shin and published by . This book was released on 2016 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: Production of biofuels at an industrial scale is a challenge that must be addressed for a green, sustainable future. One of the major goals to achieve in order to successfully manufacture biofuels in large-scale is in situ product recovery of the biofuels. This is an important issue for producing biofuels via biological pathways and also via chemical pathways. In fermentation, in situ product recovery is crucial because of product inhibition. Product inhibition is severe enough to terminate fermentation at around 20 g/L of product concentration, thus limiting the productivity and resulting in high separation costs as well as high operation costs due to batch processing. In chemical reactions for producing biofuels, in situ product removal is important in minimizing the formation of side products in the reaction, which also limits the productivity. We approach this challenge by using pervaporation, a membrane-based separation method. We have designed PDMS-derived block copolymers, which are novel materials for this application, for in situ product recovery of biofuels by pervaporation. We aim to study the physical properties of these block copolymer membranes to apply them in fermenters and chemical reactors for product recovery. Here, we first studied the structure-property relationship of PDMS-derived block copolymer membranes. The block copolymer that we have designed self-assembles into various morphologies when solvent-cast under different conditions. Comparing the morphologies of the membranes to the permeabilities of the membranes allowed us to understand the effect of morphology on permeation. The lamellar structure was the most detrimental to the permeability of the membrane; it resulted in a five-fold decrease in biofuel permeability and a three-fold decrease in biofuel selectivity. The reason for this decrease was found to be originating from the diffusion step in the permeation process. Next, the effect of support layer resistance was studied by measuring the permeabilities of membranes of different thicknesses and by direct imaging. In order to maximize the flux of block copolymer pervaporation membranes, using an additional porous membrane layer is inevitable. However, pore penetration of the block copolymer into the porous membrane results in a dramatic increase in support layer resistance. This explains the permeability decrease with decreasing membrane thickness, and by assuming a certain pore penetration layer thickness, we were able to successfully use the resistance model to fit the permeability data. In addition, we succeeded in visually confirming pore penetration of the block copolymer via transmission electron microscopy. The PDMS-derived block copolymer membrane was also applied in an in situ pervaporation setup attached to an ongoing acetone-butanol-ethanol (ABE) fermentation. We were able to successfully demonstrate a pervaporative-fermentation experiment where the ABE removal rate of the block copolymer membrane was matched to the rate of production in the fermenter. This resulted in a semi-continuous mode of operation for 109 hours. Finally, crosslinked block copolymers were studied for the application of in situ pervaporation during chemical reactions to produce biofuels. These reactions are operated above the temperatures that normal polymer membranes can withstand. Thus, we studied the possibility of forming crosslinks in the non-transporting block of the block copolymer to enhance the heat tolerance to the block copolymer membranes. We were able to form crosslinks within the polyethylene domain of a polyethylene-b-polydimethylsiloxane-b-polyethylene membrane, and discovered that the crosslinks enhanced the temperature stability of the membrane without hindering permeability.

Download or read book Block Copolymers II written by Volker Abetz and published by Springer Science & Business Media. This book was released on 2005-12-02 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: . A.J. M ller, V. Balsamo, M.L. Arnal: Nucleation and Crystallization in Diblock and Triblock Copolymers.- 2 J.-F. Gohy: Block Copolymer Micelles.- 3 M.A. Hillmyer: Nanoporous Materials from Block Copolymer Precursors.- 4 M. Li, C. Coenjarts, C.K. Ober: Patternable Block Copolymers.-

Download or read book Polymer Science A Comprehensive Reference written by and published by Newnes. This book was released on 2012-12-05 with total page 7752 pages. Available in PDF, EPUB and Kindle. Book excerpt: The progress in polymer science is revealed in the chapters of Polymer Science: A Comprehensive Reference, Ten Volume Set. In Volume 1, this is reflected in the improved understanding of the properties of polymers in solution, in bulk and in confined situations such as in thin films. Volume 2 addresses new characterization techniques, such as high resolution optical microscopy, scanning probe microscopy and other procedures for surface and interface characterization. Volume 3 presents the great progress achieved in precise synthetic polymerization techniques for vinyl monomers to control macromolecular architecture: the development of metallocene and post-metallocene catalysis for olefin polymerization, new ionic polymerization procedures, and atom transfer radical polymerization, nitroxide mediated polymerization, and reversible addition-fragmentation chain transfer systems as the most often used controlled/living radical polymerization methods. Volume 4 is devoted to kinetics, mechanisms and applications of ring opening polymerization of heterocyclic monomers and cycloolefins (ROMP), as well as to various less common polymerization techniques. Polycondensation and non-chain polymerizations, including dendrimer synthesis and various "click" procedures, are covered in Volume 5. Volume 6 focuses on several aspects of controlled macromolecular architectures and soft nano-objects including hybrids and bioconjugates. Many of the achievements would have not been possible without new characterization techniques like AFM that allowed direct imaging of single molecules and nano-objects with a precision available only recently. An entirely new aspect in polymer science is based on the combination of bottom-up methods such as polymer synthesis and molecularly programmed self-assembly with top-down structuring such as lithography and surface templating, as presented in Volume 7. It encompasses polymer and nanoparticle assembly in bulk and under confined conditions or influenced by an external field, including thin films, inorganic-organic hybrids, or nanofibers. Volume 8 expands these concepts focusing on applications in advanced technologies, e.g. in electronic industry and centers on combination with top down approach and functional properties like conductivity. Another type of functionality that is of rapidly increasing importance in polymer science is introduced in volume 9. It deals with various aspects of polymers in biology and medicine, including the response of living cells and tissue to the contact with biofunctional particles and surfaces. The last volume is devoted to the scope and potential provided by environmentally benign and green polymers, as well as energy-related polymers. They discuss new technologies needed for a sustainable economy in our world of limited resources. Provides broad and in-depth coverage of all aspects of polymer science from synthesis/polymerization, properties, and characterization methods and techniques to nanostructures, sustainability and energy, and biomedical uses of polymers Provides a definitive source for those entering or researching in this area by integrating the multidisciplinary aspects of the science into one unique, up-to-date reference work Electronic version has complete cross-referencing and multi-media components Volume editors are world experts in their field (including a Nobel Prize winner)

Download or read book Colloidal and Morphological Behavior of Block and Graft Copolymers written by Gunther Molau and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt: The molecules of block and graft copolymers are molecules of a higher order; they consist of homopolymer subchains which are interconnected by chemical valence bonds. This structural com plexity is manifested in the unusual behavior of block and graft copolymers both in solution and in bulk. Many types of interac tions are possible in block and graft copolymers in the solid state. Polymer subchains of one molecule can interact with other polymer subchains which may belong to the same molecule or to different molecules. Since polymer chains of chemically different composition are usually incompatible, thermodynamically unfavorable as well as thermodynamically favorable interactions exist in the solid state. In solutions of block and graft copolymers, the sit uation becomes even more complex, because interactions between the solvent molecules and the various subchains of the copolymer mole cules occur in addition to the interactions between the polymer chains. This multitude of interactions gives rise to a wide spec trum of colloidal and morphological properties which have no paral lel in less complex polymer systems such as homopolymers or random copolymers. Research on the colloidal and morphological behavior of block and graft copolymers is a relatively new field of endeavor. It started in 1954, when F. M. Merrett fractionated mixtures of grafted na tural rubber with the corresponding homopolymers and observed that colloidal sols were formed at certain points during his fractional precipitations.