Author: James J. WatkinsPublisher:
ISBN:
Category : Chemical engineering
Languages : en
Pages : 3
Book Description
Phase Separation in Polymer Blends and Block Copolymers Induced by Differential Dilation with CO2
Author: James J. WatkinsPublisher:
ISBN:
Category : Chemical engineering
Languages : en
Pages : 3
Book Description
Block Copolymers as Compatibilizer of Polymer Blends and Its Effect on Phase Separation
Author: Dong Won ParkPhase Behavior of Block Copolymers in Compressed CO2 and as Single Domain-layer, Nanolithographic Etch Resists for Sub-10 Nm Pattern Transfer
Author: Curran Matthew ChandlerPublisher:
ISBN:
Category : Block copolymers
Languages : en
Pages : 159
Book Description
Diblock copolymers have many interesting properties, which first and foremost include their ability to self-assemble into various ordered, regularly spaced domains with nanometer-scale feature sizes. The work in this dissertation can be logically divided into two parts - the first and the majority of this work describes the phase behavior of certain block copolymer systems, and the second discusses real applications possible with block copolymer templates. Many compressible fluids have solvent-like properties dependent on fluid pressure and can be used as processing aids similar to liquid solvents. Here, compressed CO2 was shown to swell several thin homopolymer films, including polystyrene and polyisoprene, as measured by high pressure ellipsometry at elevated temperatures and pressures. The ellipsometric technique was modified to produce accurate data at these conditions through a custom pressure vessel design. The order-disorder transition (ODT) temperatures of several poly(styrene-b-isoprene) diblock copolymers were also investigated by static birefringence when dilated with compressed CO2. Sorption of CO2 in each copolymer resulted in significant depressions of the ODT temperature as a function of fluid pressure, and the data above was used to estimate the quantitative amount of solvent in each of the diblock copolymers. These depressions were not shown to follow dilution approximation, and showed interesting, exaggerated scaling of the ODT at near-bulk polymer concentrations. The phase behavior of block copolymer surfactants was studied when blended with polymer or small molecule additives capable of selective hydrogen bonds. This work used small angle X-ray scattering (SAXS) to identify several low molecular weight systems with strong phase separation and ordered domains as small as 2-3 nanometers upon blending. One blend of a commercially-available surfactant with a small molecule additive was further developed and showed promise as a thin-film pattern transfer template. In this scenario, block copolymer thin films on domain thick with self-assembled feature sizes of only 6-7 nm were used as plasma etch resists. Here the block copolymer's pattern was successfully transferred into the underlying SiO2 substrate using CF4-based reactive ion etching. The result was a parallel, cylindrical nanostructure etched into SiO2.
Supercritical Fluids
Author: E. KiranPublisher: Springer Science & Business Media
ISBN: 9401139296
Category : Science
Languages : en
Pages : 602
Book Description
Supercritical fluids are neither gas nor liquid, but can be compressed gradually from low to high density and they are therefore interesting and important as tunable solvents and reaction media in the chemical process industry. By adjusting the density the properties of these fluids can be customised and manipulated for a given process - physical or chemical transformation. Separation and processing using supercritical solvents such as CO2 are currently on-line commercially in the food, essential oils and polymer industries. Many agencies and industries are considering the use of supercritical water for waste remediation. Supercritical fluid chromatography represents another, major analytical application. Significant advances have recently been made in materials processing, ranging from particle formation to the creation of porous materials. The chapters in this book provide tutorial accounts of topical areas centred around: (1) phase equilibria, thermodynamics and equations of state; (2) critical behaviour, crossover effects; (3) transport and interfacial properties; (4) molecular modelling, computer simulation; (5) reactions, spectroscopy; (6) phase separation kinetics; (7) extractions; (8) applications to polymers, pharmaceuticals, natural materials and chromatography; (9) process scale-up.
Block Copolymers
Author: Ashish Kumar KhandpurPublisher:
ISBN:
Category :
Languages : en
Pages : 434
Book Description
Phase Diagram of Polymer Blends Containing Block Copolymers
Author: R. J. RoePublisher:
ISBN:
Category :
Languages : en
Pages : 32
Book Description
The phase transition and phase separation behavior occurring in mixtures containing an A-B block copolymer and an A homopolymer is discussed. With a pure block copolymer an order-disorder transition can be induced by raising the temperature, whereby the ordered lattice of segregated microdomains becomes unstable and give way to a homogeneous liquid structure. Small amounts of a homopolymer added to a block copolymer can be accomodated in the microdomains consisting of the same type of monomeric units, up to a solubility limit that depends on the relative length of the homopolymer and the compolymer block and on the temperature. The order-disorder transition temperature of the block copolymer is also affected by the added homopolymer. At the other extreme of concentration, spherical micelles of block compolymer is formed when a small amount of the copolymer is formed when a small amount of the compolymer is added in the bulk homopolymer, and its critical micelle concentration again depends on the relative length of the molecules and block involved and on the temperature. Measurements were made with light scattering and small-angle X-ray scattering techniques to determine the phase behavior of mixtures containing a styrene-butadiene block copolymer and either a polystyrene or a polybutadiene.
Equilibrium and Kinetic Aspects of Phase Separation in Polymer Blends and Diblock Copolymers
Author: James Grant ConnellDynamics of Polymerization Induced Phase Separation in Reactive Polymer Blends
Author: Jaehyung LeePublisher:
ISBN:
Category : Crosslinked polymers
Languages : en
Pages : 534
Book Description
CO2-induced Phase Separation in Multi-component Polymer Systems Studied by Fluorescence Spectroscopy
Author: Vijayakumar S. RamachandraRaoPublisher:
ISBN:
Category : Chemical engineering
Languages : en
Pages : 3
Book Description
Author: Dahn Katzen