Download or read book Microstructure of Block Copolymers in the Presence of Selective Solvents written by Paschalis Alexandridis and published by . This book was released on 1998 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Controlling the Microstructure and Kinetics of Block Copolymer Self assembly by Direct Immersion Annealing written by Melanie J. Longanecker and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The self-assembly of block copolymers into periodic nanostructures has long been studied for their potential use in integrated circuits, nanofiltration devices, metamaterials, energy and data storage devices, and many more applications. Their use, however, is limited by a number of structural and kinetics challenges. The present research describes how a recently developed annealing technique, direct immersion annealing, can be used to address these challenges. The mechanism that leads to a change in domain size of up to 64% for a single molecular weight during direct immersion annealing is examined for one, two, and three-dimensional morphologies. It was found that the chain orientation within a structure has a significant impact on the structural rearrangements that occur as the result of constrained swelling. This leads to a reduction of the domain size for out-of-plane structure and an increase in domain size for in-plane structure. The non-equilibrium state of the morphology that leads to the reduced domain size leaves the chains in a non-equilibrium conformation that deviates from the tear-drop shape traditionally observed in block copolymers. SANS analysis confirms that the chains take on a flattened disc-like shape in this state. The solvent presence during direct immersion annealing also presents the ability to tune the interaction parameter of the block, where it is shown that the diffuse interface between domains can be improved by 27% using a selective solvent. The kinetics of direct immersion annealing are examined for its ability to order neat and filled block copolymer systems in rapid times. It was found that direct immersion annealing can order much faster than solvent vapor annealing due to the difference in chemical potential of bulk solvent vs. vapors. This has a significant impact on the film swelling rate, where a film submerged in bulk solvent during direct immersion annealing swells to its equilibrium thickness instantaneously, while the vapor annealed film had still not reached equilibrium after 4 h. Further, it was determined that the rapid ordering kinetics of direct immersion annealing are limited to the molecular weight regime where chains are unentangled. At higher molecular weights, the ordering diffusion coefficient scales as N-2.9.
Download or read book Amphiphilic Block Copolymers written by P. Alexandridis and published by Elsevier. This book was released on 2000-10-18 with total page 449 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is the belief of the editors of this book that the recognition of block copolymers as being amphiphilic molecules and sharing common features with other well-studied amphiphiles will prove beneficial to both the surfactant and the polymer communities. An aim of this book is to bridge the two communities and cross-fertilise the different fields. To this end, leading researchers in the field of amphiphilic block copolymer self-assembly, some having a background in surfactant chemistry, and others with polymer physics roots, have agreed to join forces and contribute to this book.The book consists of four entities. The first part discusses theoretical considerations behind the block copolymer self-assembly in solution and in the melt. The second part provides case studies of self-assembly in different classes of block copolymers (e.g., polyethers, polyelectrolytes) and in different environments (e.g., in water, in non-aqueous solvents, or in the absence of solvents). The third part presents experimental tools, ranging from static (e.g., small angle neutron scattering) to dynamic (e.g., rheology), which can prove valuable in the characterization of block copolymer self-assemblies. The fourth part offers a sampling of current applications of block copolymers in, e.g., formulations, pharmaceutics, and separations, applications which are based on the unique self-assembly properties of block copolymers.
Download or read book The Microstructure of Block Copolymer Amphiphiles Near Material Surfaces written by Mohan Sikka and published by . This book was released on 1994 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Block Copolymers written by Kenneth J. Hanley and published by . This book was released on 2001 with total page 916 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Phase Behavior of Block Copolymers in Selective Solvents written by Yongsheng Liu and published by . This book was released on 2008 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: The goal of this research is to study the phase behavior and kinetics of order-order (OOT) and order-disorder (ODT) phase transitions in block copolymers in selective solvents. We focus on examining temperature and pressure dependence of the phase diagram and the kinetics of phase transitions using small angle x-ray scattering (SAXS). The kinetics of ODT and OOT was studied for two block copolymer solutions by time-resolved SAXS using temperature ramp and fast quench methods: (i) Poly(styrene- b -isoprene) (PS-PI) diblock copolymer in tetradecane, selective solvent for PI, which displayed face-centered-cubic (FCC) structure at low temperature, body-centered-cubic (BCC) at intermediate temperature, and was disordered at high temperature. Following a quench from 110 C to 50 C, a long-lived meta-stable BCC phase was detected prior to the formation of FCC. The data agrees very well with Cahn's model for nucleation and growth. (ii) Poly(styrene- b -ethylene- co -butylene- b -styrene) triblock copolymer in dibutyl phthaphate, selective solvent for PS, which displayed hexagonally packed cylinders (HEX) at low temperature and lamellar (LAM) phase at high temperatures. This is unusual because in most block copolymer melts LAM occurs at lower temperature than HEX. A geometric model was developed to understand the mechanism of the transition from LAM to HEX. The calculated scattering intensity agrees very well with the experimental data. A pressure network system for SAXS capable of operating in the range of 1-4000 bars with pressure jump capability was built to study the pressure dependence of phase behavior. The system was used to investigate PS-PI diblock copolymer in diethyl phthaphate. The BCC to disorder transition temperature increased with pressure at 20 C/kbar, and the lattice constant increased with pressure. Brownian Molecular Dynamics simulations were carried out to study the phase behavior of multiblock copolymers in a selective solvent. Disordered, BCC, HEX, and LAM phases were obtained depending on the concentration and number of blocks. This research provides detailed information of the kinetics of structural changes in block copolymers in selective solvents. The results provide a good understanding of the mechanism of order-disorder and order-order transitions, and are directly related to industrial applications of block copolymers.
Download or read book Soft Matter Characterization written by Redouane Borsali and published by Springer Science & Business Media. This book was released on 2008-07-28 with total page 1490 pages. Available in PDF, EPUB and Kindle. Book excerpt: This 2-volume set includes extensive discussions of scattering techniques (light, neutron and X-ray) and related fluctuation and grating techniques that are at the forefront of this field. Most of the scattering techniques are Fourier space techniques. Recent advances have seen the development of powerful direct imaging methods such as atomic force microscopy and scanning probe microscopy. In addition, techniques that can be used to manipulate soft matter on the nanometer scale are also in rapid development. These include the scanning probe microscopy technique mentioned above as well as optical and magnetic tweezers.
Download or read book Block Copolymers in Solution written by Ian W. Hamley and published by Wiley. This book was released on 2005-12-13 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt: This unique text discusses the solution self-assembly of block copolymers and covers all aspects from basic physical chemistry to applications in soft nanotechnology. Recent advances have enabled the preparation of new materials with novel self-assembling structures, functionality and responsiveness and there have also been concomitant advances in theory and modelling. The present text covers the principles of self-assembly in both dilute and concentrated solution, for example micellization and mesophase formation, etc., in chapters 2 and 3 respectively. Chapter 4 covers polyelectrolyte block copolymers - these materials are attracting significant attention from researchers and a solid basis for understanding their physical chemistry is emerging, and this is discussed. The next chapter discusses adsorption of block copolymers from solution at liquid and solid interfaces. The concluding chapter presents a discussion of selected applications, focussing on several important new concepts. The book is aimed at researchers in polymer science as well as industrial scientists involved in the polymer and coatings industries. It will also be of interest to scientists working in soft matter self-assembly and self-organizing polymers.
Download or read book Block Polymers written by S. L. Aggarwal and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 337 pages. Available in PDF, EPUB and Kindle. Book excerpt: Block polymers represent another milestone in the preparation of polymers of controlled structure. Catalysts and polymerization methods that allowed the preparation of polymers in which the stereo- and geometric isomerism of the monomer units could be con trolled have indeed been among the major developments in polymer science during the last decade. The synthesis of block polymers, in which the sequence length of the comonomer units can be con trolled, portends equally important developments in the science and technology of polymers. The papers collected in this volume cover primarily the pro ceedings of the most recent symposium on block polymers, sponsored by the Division of Polymer Chemistry of the American Chemical Society. It was held in New York City during the Society's 158th National Meeting in September, 1969. Additional contributions from selected authors were invited especially for this book to achieve the most up-to-date account of the advances that have been made since the development of the thermoplastic elastomers that first brought into focus this important area of research. The first two papers in this volume draw attention to the various problems that should be considered in the preparation of block polymers of precisely defined structure from styrene and butadiene or isoprene by anionic polymerization. Characterization of block polymers presents many problems and there is a paucity of systematic work in this area. Attention has been given to the di lute solution properties of block polymers,however, in one of the papers in this volume.
Download or read book Block Copolymers written by Francisco Balta Calleja and published by CRC Press. This book was released on 2000-06-09 with total page 604 pages. Available in PDF, EPUB and Kindle. Book excerpt: A summary of block copolymer chemical structures and synthesis. It discusses physical methods of characterization such as computer simulation, microhardness, dielectric spectroscopy, thermal mechanical relaxation, ultrasonic characterization, transmission electron microscopy, X-ray scattering, and NMR, among others. It also outlines rheological and processing parameters in the multiphase polymer systems with stable microstructures.
Download or read book Amphiphilic Block Copolymers in Aqueous Polar Organic Solvent Mixtures written by Jinendra Lakshmichand and published by . This book was released on 2010 with total page 117 pages. Available in PDF, EPUB and Kindle. Book excerpt: Amphiphilic block copolymers of the poly(ethylene oxide)-poly(propylene oxide) (PEO-PPO) family are well known for self-assembling in the presence of water (selective solvent for PEO) into cubic, hexagonal and lamellar lyotropic liquid crystals. We are interested on how the aqueous phase behavior and structure of these polymeric amphiphiles can be modulated by the addition of polar organic solvents (e.g., glycerol, ethanol). Mixtures of water with two organic solvents (glycerol and ethanol) constitute a specific focus of this work. Our studies combine macroscopic observations (e.g., phase diagrams) with microscopic measurements (from small-angle X-ray scattering), and aim to relate the type of structure formed and its characteristic dimensions to the relative swelling of the polymer blocks and to the location of the solvent in the amphiphile assembly. Solvent-induced structural changes of block copolymers have interesting repercussions on the formulations and nonmaterial's synthesis in such media.
Download or read book Modeling Self assembly and Structure property Relationships in Block Copolymers written by Manas Ravindra Shah and published by . This book was released on 2009 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt: Block copolymers have been subject of tremendous research interest owing to their capability of undergoing self-assembly which allows them to tailor their electrical, optical, and mechanical properties. Statistical mechanics of flexible block copolymers is well understood. However, there are many unresolved issues with confinement of block copolymers as well as structure formation in block copolymers having non-flexible polymer blocks. We develop mean field theory models to address the issues arising in thermodynamics of such complex block copolymers. Also, we develop theoretical formalisms to understand the link between morphology and macroscopic properties in these block copolymers. We study the stability and ordering in thin films of flexible diblock copolymer in the presence of compressible solvent using a combined polymer mean field theory and lattice gas model for binary fluid mixtures. We utilize mean field theory model to understand the self-assembly behavior in side-chain liquid crystalline block copolymers which involve interplay between microphase separation and liquid crystalline ordering of side chain mesogenic units. We extend the field theoretic models for block copolymer to account for self-assembly in semicrystalline block copolymers. The semicrystalline chain is modeled as a semiflexible chain having non-bonded attractions between parallel bonds. We characterize the structure formation in such block copolymers as a function of the rigidity of the semicrystalline chain. Then we extend the formalism to study semicrystalline triblock and pentablock copolymers and evaluate bridging fractions in different sequences of semicrystalline multiblock copolymers. Rod-coil block copolymers have a flexible polymer covalently linked to rigid polymer. Such polymers have potential applications as organic LEDs and photovoltaic devices. We study the self-assembly of such block copolymer under confinement. To make these block copolymers viable as photovoltaic devices, we performed the photovoltaic modeling of devices based on self-assembly of block copolymers. We characterize the interplay between self-assembly and anisotropy of charge transport (arising due to rigid polymer chains) in determining the eventual photovoltaic properties.
Download or read book The Study of Amphiphilic Block Copolymers in Selective Solvents written by Sharon L. Wells and published by . This book was released on 2000 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Block Copolymer Dynamics and Microstructure written by Ziwei Liu and published by . This book was released on 1996 with total page 406 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Thermodynamic and Kinetic Control of Charged Amphiphilic Triblock Copolymer Assembly Via Interaction with Organic Counterions in Solvent Mixtures written by Honggang Cui and published by . This book was released on 2007 with total page 195 pages. Available in PDF, EPUB and Kindle. Book excerpt: The interaction of positively-charged, multivalent organic amines with the negatively-charged PAA corona plays a decisive role in the formation of these micelles. Inter-chain binding from the interaction of the two amine end groups of diamines with acid groups from different PAA corona blocks governs the final assembled structures. Diamines with hydrophilic spacers induced the formation of micelles with larger interfacial curvature as the spacer length increased. Disk-like micelles, cylindrical micelles or spherical micelles were observed with the gradual increase of hydrophilic spacer length. Diamines with variable hydrophobic spacers showed a similar effect when the spacer length was less than six methylene units. Application of longer hydrophobic diamines had a reverse effect on the interfacial curvature. This effect was attributed to the interaction of hydrophobic diamine hydrocarbon linking chains with the PMA-b-PS hydrophobic core. These findings indicate an easy method to tune micelle structure with multivalent organic counterions. (Abstract shortened by UMI.)
