Download or read book Influence of Morphology and Interfaces on Self diffusion of Microphase Separated Diblock Copolymers and Their Blends Studied by Pulsed Field Gradient NMR written by Frank Rittig and published by . This book was released on 2001 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2005 with total page 918 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.

Download or read book Controlling Morphology of Multi component Block Copolymer Based Materials written by Rafal Adam Mickiewicz and published by . This book was released on 2009 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ability of block copolymers to self-assemble into ordered microstructures has attracted much interest both from a pure scientific perspective and for their potential in numerous industrial applications. The microphase separation of block copolymers has been successfully exploited in a wide range of applications, such as templating and lithography, enhancement of mechanical properties, and nano reactor schemes. This thesis focuses on the characterization of the morphology in composite systems where one or more of the components is a block copolymer. In the first part of this thesis, binary blends of very high molecular weight diblock copolymers with a low molecular weight triblock copolymer are investigated. The high molecular weight diblock copolymers are very strongly segregating, with interaction parameter values, XN, in the range 470 - 1410. The phase diagram revealed a large miscibility gap for the blends, with macrophase separation into two distinct types of microphase separated domains and implied virtually no solubility of the much higher molecular weight diblocks in the triblock. For certain blend compositions, morphological transitions from the lamellar to cylindrical and bicontinuous structures were also observed, even though the overall composition in the blend would be expected to favor the lamellar microstructure. This was found to result from the compositional asymmetry of the triblock copolymer influencing the curvature of the inter-material dividing surface (IMDS). Finally, a strong segregation theory model was used to interpret the observed results. In the second part of this thesis the microstructure formation in nanocomposites based on a liquid crystalline side chain block copolymer (LCBCP) and gold nanoparticles was investigated. The location of the nanoparticles was found to not only depend on the surface chemistry of the gold nanoparticles, but also on the self-organization within the liquid crystalline domain of the LCBCP. The nanoparticles were excluded from the liquid crystalline domains due to the high free energy penalty of disrupting the smectic layering. The final location of the nanoparticles within the composite was determined by the nature of the stabilizing surface coating. The work presented in this thesis revealed a number of interesting tools which are useful for obtaining a wide range of morphologies in multi-component block copolymer systems.

Download or read book Double Gyroid Structured Functional Materials written by Maik Rudolf Johann Scherer and published by Springer Science & Business Media. This book was released on 2013-06-25 with total page 211 pages. Available in PDF, EPUB and Kindle. Book excerpt: The development of new high-tech applications and devices has created a seemingly insatiable demand for novel functional materials with enhanced and tailored properties. Such materials can be achieved by three-dimensional structuring on the nanoscale, giving rise to a significant enhancement of particular functional characteristics which stems from the ability to access both surface/interface and bulk properties. The highly ordered, bicontinuous double-gyroid morphology is a fascinating and particularly suitable 3D nanostructure for this purpose due to its highly accessible surface area, connectivity, narrow pore diameter distribution and superb structural stability. The presented study encompasses a wide range of modern nanotechnology techniques in a highly versatile bottom-up nanopatterning strategy that splits the fabrication process into two successive steps: the preparation of mesoporous double-gyroid templates utilizing diblock copolymer self-assembly, and their replication with a functional material employing electrochemical deposition and atomic layer deposition. The double-gyroid structured materials discussed include metals, metal oxides, and conjugated polymers, which are applied and characterized in high-performance devices, such as electrochromic displays, supercapacitors, chemical sensors and photovoltaics. This publication addresses a wide range of readers, from researchers and specialists who are professionally active in the field, to more general readers interested in chemistry, nanoscience and physics.

Download or read book Tuning Melt phase Morphology in Block Copolymers Using Block Dispersity written by and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Block copolymers non-linearly combine the properties of two different homopolymers into a single material, by virtue of the connectivity between the two distinct homopolymer segments. Their microphase separation at the nanoscale leads to the formation of interesting and useful microstructures, such as spheres and cylinders ordered on regular lattices with high degrees of long-range order. The advent of newer controlled radical and tandem polymerization techniques enables the enchainment of an ever increasing number of functional monomers with new properties, yet these techniques typically result in copolymers with broader molecular weight dispersities. A thorough understanding of the morphological consequences of increased molecular weight dispersity in one or more segments in a block copolymer will enable the development of new materials incorporating unusual monomers with new chemical functionalities and properties. Herein, we describe the synthesis and characterization of a library of poly(lactide-b-1,4-butadiene-b-lactide) (LBL) triblock copolymer samples with broad dispersity center segments, and we compare their melt-phase self-assembly behavior to previously reported polydisperse SBS triblock copolymers. Based on these comparisons, we rationalize the dramatically different behaviors of the two systems in terms of specific chain packing arrangements that depend upon the degree of chemical incompatibility of the copolymer system. In an attempt to mimic the most important molecular heterogeneities of continuously polydisperse copolymers as identified by our studies, we designed bidisperse blends of triblock copolymers and studied their morphological and uniaxial mechanical properties. As with continuously polydisperse copolymers, these blends also adopted bicontinuous morphologies with substantial mechanical toughness. In the latter part of this thesis, we investigate the influence of macromolecular dispersity on the macrophase separation behavior of mixtures of poly(vinyl alcohol) (PVA) and poly(ethylene oxide) (PEO) co-dissolved in water. The location of the concentration-dependent phase boundary, which separates the phase separated and phase mixed regions, is shown to depend on both the average molecular weight and dispersity of the polymeric components. Colloidal and copolymer surfactant additives are further shown to improve ATPS emulsion stability at higher temperatures and to mitigate emulsion coarsening.

Download or read book Microphase and Macrophase Separation in Binary and Ternary Block Copolymer Blends written by Michal Banaszak and published by . This book was released on 1991 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Small Angle Scattering Investigation of the Microphase Separation Transition in Diblock Copolymers and Diblock Copolymer homopolymer Blends written by John Neal Owens and published by . This book was released on 1986 with total page 774 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Diffusion in Microstructured Block Copolymers written by Christine Elizabeth Eastman and published by . This book was released on 1993 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Characterization of Polymer Blends written by Sabu Thomas and published by John Wiley & Sons. This book was released on 2015-02-09 with total page 972 pages. Available in PDF, EPUB and Kindle. Book excerpt: Filling the gap for a reference dedicated to the characterization of polymer blends and their micro and nano morphologies, this book provides comprehensive, systematic coverage in a one-stop, two-volume resource for all those working in the field. Leading researchers from industry and academia, as well as from government and private research institutions around the world summarize recent technical advances in chapters devoted to their individual contributions. In so doing, they examine a wide range of modern characterization techniques, from microscopy and spectroscopy to diffraction, thermal analysis, rheology, mechanical measurements and chromatography. These methods are compared with each other to assist in determining the best solution for both fundamental and applied problems, paying attention to the characterization of nanoscale miscibility and interfaces, both in blends involving copolymers and in immiscible blends. The thermodynamics, miscibility, phase separation, morphology and interfaces in polymer blends are also discussed in light of new insights involving the nanoscopic scale. Finally, the authors detail the processing-morphology-property relationships of polymer blends, as well as the influence of processing on the generation of micro and nano morphologies, and the dependence of these morphologies on the properties of blends. Hot topics such as compatibilization through nanoparticles, miscibility of new biopolymers and nanoscale investigations of interfaces in blends are also addressed. With its application-oriented approach, handpicked selection of topics and expert contributors, this is an outstanding survey for anyone involved in the field of polymer blends for advanced technologies.

Download or read book Morphology and Properties of Segmented Copolymers and Blends written by Carl Baa-sun Wang and published by . This book was released on 1982 with total page 634 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Maro Polymer Notes written by and published by . This book was released on 1994 with total page 882 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Computer Simulations in Block Copolymers Charged Colloidal Particles and Polyelectrolytes written by and published by . This book was released on 2007 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work, nano-structures of block copolymer melts, self-assembling between charged nano-particles and polyelectrolytes were investigated by computer simulations. In the first chapter, the developments in the fields of microphase separation in block copolymers and self-assembling of polyelectrolytes were introduced in general. In chapter 2, a modified bond-fluctuation and vacancy diffusion lattice Monte Carlo algorithm were presented. By employing this algorithm, the morphologies of ABA and ABC triblock copolymer melts confined in two parallel walls were studied in chapters 2 and 3 respectively. In ABA triblock copolymer melts, parallel lamellae, perforated lamellae, mesh-like morphologies and normal lamellae as well as parallel cylinders and normal cylinders were identified. In ABC triblock copolymer melts, ABCCBA alternate lamellae, "tricolor checkerboard like" morphology and other special morphologies were observed. In chapters 4 and 5, employing Monte Carlo simulations, the effects of confinements from the nano-cylindrical tube on the copolymer morphology were investigated. In chapter 4, the morphology transitions in AB diblock copolymer melts were examined in detail and a variety of helical morphologies and complex mesh morphologies were found. In chapter 5, much more novel morphologies were identified in ABC triblock copolymer melts. In chapter 6, a mesoscopic approach, cell dynamic system (CDS) was extended to diblock copolymer melts in electric fields and the coupled orthogonal electric and shear fields. The long-range lamellae and cylinders, which cannot be obtained under the surface field, were achieved in AB diblock copolymer melts by applying above long-range external fields. Furthermore, the dynamics of pattern evolution of AB diblock copolymer melts were also studied in chapter 6. In chapter 7, the effective potentials between particles subjected to van der Waals and electrostatic pair interactions were calculated by off-lattice Monte Carlo simulations. The simulation results have shown that an effective attractive interaction can be generated even though there was no attractive component in the pair potential employed because of many-body effects. In chapter 8, off-lattice Monte Carlo simulations were applied to examine the adsorption of a single polyampholyte on a single charged nano-particle. The simulations revealed that there are three conformation regimes of the complex. When both of the charge density and the particle size were small, the chain kept largely the configurations, which it would have had when it was alone in the bulk. By increasing the charge density and the particle size, the polyampholyte chain collapsed on the surface of the particle. A further increase of the above two factors leaded to a separation between the subchains with positive and negative charges. In chapter 9, self-recognition between diblock polyelectrolytes was studied. Both matched lengths and charge numbers were important factors in the process of self-recognition. Furthermore, matching chains can form larger and tighter aggregates, with more coiled chains than those in unmatched aggregates or network structures.

Download or read book Surface and Bulk Phase Separations in Block Copolymers and Their Blends written by Niranjan M. Patel and published by . This book was released on 1984 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface and bulk properties have been studied in terms of composition and morphology of siloxane containing block copolymers and their blends with homopolymers. X-ray Photoelectron Spectroscopy (XPS) has been used to obtain the compositional information from the top 60 angstroms or so at the surface. Transmission Electron Microscopy (TEM) was utilized to probe the bulk morphology. An attempt is made to compare the bulk and the surface and find possible mechanisms governing them. It is found that solvent-cast neat block copolymers have a uniform layer at the surface that is rich in siloxane whereas their bulk has a microphase-separated domain structure. In case of blends, siloxane enrichment is quite pronounced even at bulk concentrations as low as 0.05% w/w siloxane. Amount of surface siloxane as a function of bulk content is studied with the help of XPS. At the same time, the bulk morphology of these blends is studied by TEM. The changes occuring in the surface and the bulk are found to have similar patterns.

Download or read book Block Copolymer Self assembly a Computational Approach Towards Novel Morphologies written by Karim Raafat Gadelrab and published by . This book was released on 2019 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: Spontaneous self-assembly of materials is a phenomenon exhibited by different molecular systems. Among many, Block copolymers (BCPs) proved to be particularly interesting due to their ability to microphase separate into periodic domains. Nonetheless, the rising need for arbitrary, complex, 3D nanoscale morphology shows that what is commonly achievable is quite limited. Expanding the range of BCPs morphologies could be attained through the implementation of a host of strategies that could be used concurrently. Using directed self-assembly (DSA), a sphere forming BCP was assembled in a randomly displaced post template to study system resilience towards defect creation. Template shear-like distortion seemed to govern local defect generation. Defect clusters with symmetries compatible with that of the BCP showed enhanced stability. Using 44 and 32434 Archimedean tiling templates that are incompatible with BCP six-fold symmetry created low symmetry patterns with an emergent behavior dependent on pattern size and shape. A variation of DSA is studied using modulated substrates. Layer-by-layer deposition of cylinder forming BCPs was investigated. Self-consistent field theory (SCFT) and strong segregation theory SST were employed to provide the understanding and the conditions under which particular orientations of consecutive layers were produced. Furthermore, deep functionalized trenches were employed to create vertically standing high-[chi] BCP structures. Changing annealing conditions for a self-assembled lamellar structure evolved the assembled pattern to a tubular morphology that is non-native to diblock copolymers. A rather fundamental but challenging strategy to go beyond the standard motifs common to BCPs is to synthesize multiblock molecules with an expanded design space. Triblock copolymers produced bilayer perforated lamellar morphology. SCFT analysis showed a large window of stability of such structures in thin films. In addition, a model for bottlebrush BCPs (BBCPs) was constructed to investigate the characteristics of BBCPs self-assembly. Pre-stacked diblock sidechains showed improved microphase separation while providing domain spacing relevant to lithography applications. A rich phase diagram was constructed at different block concentrations. The ability to explore new strategies to discover potential equilibrium morphologies in BCPs is supported by strong numerical modeling and simulations efforts. Accelerating SCFT performance would greatly benefit BCP phase discovery. Preliminary work discussed the first attempt to Neural Network (NN) assisted SCFT. The use of NN was able to cut on the required calculations steps to reach equilibrium morphology, demonstrating accelerated calculation, and escaping trapped states, with no effect on final structure.

Download or read book Molecular Study of the Structure and Morphology of Diblock Copolymers on Nano patterened Substrates written by Quiang Wang and published by . This book was released on 2002 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Polymer Morphology written by Qipeng Guo and published by John Wiley & Sons. This book was released on 2016-05-16 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: With a focus on structure-property relationships, this book describes how polymer morphology affects properties and how scientists can modify them. The book covers structure development, theory, simulation, and processing; and discusses a broad range of techniques and methods. • Provides an up-to-date, comprehensive introduction to the principles and practices of polymer morphology • Illustrates major structure types, such as semicrystalline morphology, surface-induced polymer crystallization, phase separation, self-assembly, deformation, and surface topography • Covers a variety of polymers, such as homopolymers, block copolymers, polymer thin films, polymer blends, and polymer nanocomposites • Discusses a broad range of advanced and novel techniques and methods, like x-ray diffraction, thermal analysis, and electron microscopy and their applications in the morphology of polymer materials