Download or read book Effect of Monomer Sequencing on the Phase Behavior of Neat Block Copolymers and Copolymer homopolymer Blends written by Jonathan Harold Laurer and published by . This book was released on 1994 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effect of Monomer Sequencing on the Phase Behavior of Novel Block Copolymer homopolymer Blends written by J. H. Laurer and published by . This book was released on 1996 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Block Copolymers written by Ashish Kumar Khandpur and published by . This book was released on 1995 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Phase Diagram of Polymer Blends Containing Block Copolymers written by R. J. Roe and published by . This book was released on 1984 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Probing the Phase Behavior of ABC Triblock Copolymers Near Network Phase Windows written by Maeva S. Tureau and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Block copolymers are one class of soft materials that consist of two or more covalently-bonded chains of chemically distinct monomers. Their ability to self-assemble into a variety of nanostructured materials with tailored chemical and physical properties has motivated extensive investigations for use in many emerging nanotechnologies such as nanotemplates, analytical separation membranes, and electrical and ionic conductors. Relative to cylindrical nanostructures that often require external alignment techniques to minimize structural defects, network structures possess co-continuous percolating domains in three-dimension and exhibit superior mechanical stability, short diffusion path lengths, and high internal interfacial areas, which can facilitate transport in applications such as water filtration and ion-conducting membranes. In this thesis project, the poly(ethylene- alt -propylene- b -styrene- b -methyl methacrylate) (EPSM) triblock copolymer system was produced from the selective poly(isoprene) hydrogenation of poly(isoprene- b -styrene- b -methyl methacrylate) (ISM) precursors. The EPSM system was selected due to the toughness given by the combined interactions of the glassy poly(styrene) (PS) and rubbery poly(ethylene- alt -propylene) (PEP) blocks, the mechanical strength provided by the PS block, and the ease of removal of the poly(methyl methacrylate) (PMMA) block. This dissertation first presents the phase behavioral exploration of anionically-synthesized ISM triblock copolymer precursors and associated ISM copolymer/homopolymer blends, which permitted the identification and refinement of network phase regions. The copolymer/homopolymer blending technique allowed for homopolymer-induced phase transformations to and from network structures where alternating gyroid (Q 214), core-shell gyroid (Q 230), and orthorhombic (O 70) network phases were identified. The ISM phase behavior was found to qualitatively match the predicted self-consistent mean field theory (SCFT) phase behavior of a model ABC triblock copolymer described by Tyler et al. Minor discrepancies in the size and location of the phase boundaries are rationalized on the basis of the block copolymer parameters. Second, this blending technique allowed for the precise targeting of multiple nanostructures from a single, low molecular weight disordered material. The latter finding is envisioned to be particularly useful for applications requiring materials of small feature sizes while retaining the ease of processability provided by the parent disordered copolymers. Finally, the PI hydrogenation of ISM precursors generated EPSM materials with enhanced resistance to oxidative, thermal, and UV degradation. Their initial morphological characterization permitted the identification of a relatively large Q 230 network phase region and highlighted the differences in phase behavior between the EPSM and ISM precursor systems. Altogether, this latter study established a foundation for generating environmentally-stable nanostructured materials, in view of creating functionalized nanoporous membranes able to capture and separate a wide range of biologically active molecules.
Download or read book Conformation Dependent Design of Sequences in Copolymers I written by Alexei R. Khokhlov and published by Springer Science & Business Media. This book was released on 2006-02-10 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Phase Behavior of Model ABC Triblock Copolymers written by Joon Chatterjee and published by . This book was released on 2007 with total page 554 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Self assembly Behavior of Block Copolymer homopolymer Blends in Thin Films written by Shuaigang Xiao and published by . This book was released on 2004 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Publications of the National Institute of Standards and Technology Catalog written by National Institute of Standards and Technology (U.S.) and published by . This book was released on 1994 with total page 1162 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Thermodynamics and Surfactancy of Block Copolymers in Multicomponent Polyolefin Blends written by Joon-Hyung Lee and published by . This book was released on 2002 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Phase Behavior of Block Copolymers in Compressed CO2 and as Single Domain layer Nanolithographic Etch Resists for Sub 10 Nm Pattern Transfer written by Curran Matthew Chandler and published by . This book was released on 2011 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Block Copolymer Blend Phase Behavior written by Paul Martin Lipic and published by . This book was released on 1998 with total page 454 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Effects of Interactions on the Phase Behavior and Morphology of a Block Copolymer Blended with Various Polymers written by John Patrick Baetzold and published by . This book was released on 1993 with total page 398 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Phase Behavior Structure and Properties of Model Block Polymers written by and published by . This book was released on 1993 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: This project brought together three distinct experimental methods in an integrated investigation of the phase behavior, structure and properties of block copolymers in the vicinity of the order-disorder transition. Anionic polymerization of polydiene diblock copolymers followed by catalytic hydrogenation was used to produce three classes of model saturated hydrocarbon materials. Dynamic mechanical spectroscopy and large amplitude dynamic shearing were employed to probe and manipulate, respectively, the melt state microstructure. Small angle neutron scattering (SANS) experiments provided detailed information regarding the structure of the materials. A significant achievement during this work was the development of a dynamic shearing device that could be operated in situ with a SANS instrument. Together with the spectrum of materials produced, this combined scattering-rheology technique has led to a qualitative improvement in our understanding of block copolymer phase behavior, and uncovered a rich polymorphism that is accompanied by dramatic variations in physical properties. Two new parameters have been shown to play a crucial role in determining block copolymer phase behavior. The degree of polymerization, controls the extent of composition fluctuations which strongly affects the types of phases encountered near the order-disorder transition. Conformational asymmetry, which is controlled by the block volume and radius of gyration, leads to different phases on either side of the phase diagram. These effects have not been accounted for theoretically.
Download or read book Three dimensional Structural Characterization of Chromosome Pairing and Synapsis written by Jennifer C. Fung and published by . This book was released on 1996 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Influence of Architecture on the Behavior of Microphase Separated Block Copolymers written by and published by . This book was released on 2015 with total page 243 pages. Available in PDF, EPUB and Kindle. Book excerpt: The nanoscale self–assembly of block copolymers at the ~10–100 nm length scale has exciting potential applications in next–generation nanolithography and nanotemplating, wherein the feature sizes are governed by the overall copolymer degree of polymerization, N. However, the thermodynamics of block copolymer microphase separation intrinsically limit the size of the smallest features accessible by this approach. This limitation stems from the fact that AB diblock copolymer self–assembly only occurs above a critical N that depends inversely on the magnitude of the effective interaction parameter cChi, which quantifies the energetic repulsions between the dissimilar monomer segments. In this dissertation, we first provide an overview of current routes to smaller periodicities in self-assembled block copolymers. While numerous reports have focused on developing “high Chi” AB diblocks that self–assemble at smaller values of N, the use of complex macromolecular architectures to stabilize ordered block copolymer nanostructures remains relatively unexplored. We report the melt–phase self–assembly behavior of block copolymer bottlebrushes derived from linking the block junctions of low molecular weight, symmetric poly(styrene–b–lactide) (PS-b-PLA) copolymers. These studies quantitatively demonstrate that increasing the bottlebrush backbone degree of polymerization (Nbackbone) reduces the critical PS-b-PLA copolymer arm degree of polymerization (Narm) required for self–assembly into lamellar mesophases by as much as 75%, thus reducing the nanoscale feature sizes accessible with this monomer chemistry. In studies of asymmetric block copolymer bottlebrushes, we observe a less significant reduction in the Narm required for self–assembly into a hexagonally-packed cylinders morphology. These results are rationalized in terms of how monomer concentration fluctuation effects manifest upon ordering a disordered copolymer into either a lamellar or cylindrical morphology. Finally, the chemistry and physics of two other block copolymer systems are explored: (1) the self-assembly, thin film template fabrication, and post fabrication-template modification of reactive poly(styrene-b-vinyl dimethyl azalactone) block copolymers, and (2) the synthesis and rheological characteristics of amphiphilic poly(vinyl alcohol)–based ABA triblock copolymer hydrogels.
