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Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
A detailed study of the dynamics of cadmium sulfide nanoparticles suspended in polystyrene homopolymer matrices was carried out using X-ray photon correlation spectroscopy for temperatures between 120 and 180 °C. For low molecular weight polystyrene homopolymers, the observed dynamics show a crossover from diffusive to hyper-diffusive behavior with decreasing temperatures. For higher molecular weight polystyrene, the nanoparticle dynamics appear hyper-diffusive at all temperatures studied. The relaxation time and characteristic velocity determined from the measured hyper-diffusive dynamics reveal that the activation energy and underlying forces determined are on the order of 2.14 × 10-19 J and 87 pN, respectively. We also carried out a detailed X-ray scattering study of the static and dynamic behavior of a styrene- isoprene diblock copolymer melt with a styrene volume fraction of 0.3468. At 115 and 120 °C, we observe splitting of the principal Bragg peak, which we attribute to phase coexistence of hexagonal cylindrical and cubic double- gyroid structure. In the disordered phase, above 130 °C, we have characterized the dynamics of composition fluctuations via X-ray photon correlation spectroscopy. Near the peak of the static structure factor, these fluctuations show stretched-exponential relaxations, characterized by a stretching exponent of about 0.36 for a range of temperatures immediately above the MST. The corresponding characteristic relaxation times vary exponentially with temperature, changing by a factor of 2 for each 2 °C change in temperature. At low wavevectors, the measured relaxations are diffusive with relaxation times that change by a factor of 2 for each 8 °C change in temperature.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
A detailed study of the dynamics of cadmium sulfide nanoparticles suspended in polystyrene homopolymer matrices was carried out using X-ray photon correlation spectroscopy for temperatures between 120 and 180 °C. For low molecular weight polystyrene homopolymers, the observed dynamics show a crossover from diffusive to hyper-diffusive behavior with decreasing temperatures. For higher molecular weight polystyrene, the nanoparticle dynamics appear hyper-diffusive at all temperatures studied. The relaxation time and characteristic velocity determined from the measured hyper-diffusive dynamics reveal that the activation energy and underlying forces determined are on the order of 2.14 × 10-19 J and 87 pN, respectively. We also carried out a detailed X-ray scattering study of the static and dynamic behavior of a styrene- isoprene diblock copolymer melt with a styrene volume fraction of 0.3468. At 115 and 120 °C, we observe splitting of the principal Bragg peak, which we attribute to phase coexistence of hexagonal cylindrical and cubic double- gyroid structure. In the disordered phase, above 130 °C, we have characterized the dynamics of composition fluctuations via X-ray photon correlation spectroscopy. Near the peak of the static structure factor, these fluctuations show stretched-exponential relaxations, characterized by a stretching exponent of about 0.36 for a range of temperatures immediately above the MST. The corresponding characteristic relaxation times vary exponentially with temperature, changing by a factor of 2 for each 2 °C change in temperature. At low wavevectors, the measured relaxations are diffusive with relaxation times that change by a factor of 2 for each 8 °C change in temperature.
Author: Galder Kortaberria Publisher: CRC Press ISBN: 9814669555 Category : Technology & Engineering Languages : en Pages : 360
Book Description
This book provides a comprehensive overview of the synthesis and characterization of nanocomposites based on block copolymers. Because of the self-assembly capability of block copolymers for the generation of nanostructures, besides their ability to nanostructure thermosetting matrices such as epoxy and polyester, binary or ternary nanocomposites can be prepared with different nanofillers such as nanoparticles and carbon nanotubes. The book starts with a review on nanocomposites based on block copolymers and nanoparticles synthesized with the use of surfactants, followed by a review on nanocomposites with metallic nanoparticles with polymer brushes and those with carbon nanotubes. A chapter is devoted to binary systems based on block copolymers and nanoparticles synthesized by sol-gel. A review on nanocomposites based on thermosetting matrices nanostructured with block copolymers (amphiphilic or chemically modified) is also presented for both epoxy and polyester resins. The work on ternary systems based on thermosetting matrices, block copolymers, and nanoparticles is presented next. The book concludes with a discussion on nanocomposites based on epoxy and block copolymers with azobenzene groups for optical purposes.
Author: Galder Kortaberria Publisher: CRC Press ISBN: 1315341182 Category : Science Languages : en Pages : 339
Book Description
This book provides a comprehensive overview of the synthesis and characterization of nanocomposites based on block copolymers. Because of the self-assembly capability of block copolymers for the generation of nanostructures, besides their ability to nanostructure thermosetting matrices such as epoxy and polyester, binary or ternary nanocomposites can be prepared with different nanofillers such as nanoparticles and carbon nanotubes. The book starts with a review on nanocomposites based on block copolymers and nanoparticles synthesized with the use of surfactants, followed by a review on nanocomposites with metallic nanoparticles with polymer brushes and those with carbon nanotubes. A chapter is devoted to binary systems based on block copolymers and nanoparticles synthesized by sol-gel. A review on nanocomposites based on thermosetting matrices nanostructured with block copolymers (amphiphilic or chemically modified) is also presented for both epoxy and polyester resins. The work on ternary systems based on thermosetting matrices, block copolymers, and nanoparticles is presented next. The book concludes with a discussion on nanocomposites based on epoxy and block copolymers with azobenzene groups for optical purposes.
Author: Vinay Raman Publisher: ISBN: Category : Languages : en Pages : 147
Book Description
This computational and theoretical study investigates the self-assembly of superparamagnetic nanoparticles and block copolymers under external magnetic fields. A variety of morphological transitions are observed based on the field orientation, nanoparticle loading, and selectivity of the nanoparticles for the blocks. For symmetric block copolymers, chaining of superparamagnetic nanoparticles under in-plane magnetic fields is shown to achieve long range orientational order of the block copolymer nanodomains and is found to be dependent on nanoparticle size, volume fraction and magnetization strength. A critical selectivity of the particles for one nanodomain is observed, above which strong alignment results and below which comparatively disordered structures are formed. Higher magnetization strengths are found to reduce equilibrium defect densities in the nematic-isotropic ordering of lamellar thin films, as corroborated by scaling arguments. For asymmetric coil fractions forming hexagonal block copolymer nanostructure, the inplane field induced chaining of the nanoparticles selective for the minority block, leads to the formation of stripe phases oriented parallel to the magnetic field. Furthermore, in-plane field induced chaining of nanoparticles selective for the majority block leads to alignment of hexagonal morphology with 100 direction oriented parallel to the external magnetic field. Out of plane magnetic fields induce repulsive dipolar interactions between the nanoparticles that annihilate the defects in the hexagonal morphology of the block copolymer when the nanoparticle is selective for the minority block. Honeycomb lattices are obtained using nanoparticles selective for majority block under out of plane magnetic fields for certain specific nanoparticle loadings. Commensurability of nanoparticle size and loadings with the block copolymer structure is critical in optimizing the ordering of the final composite. Kinetics of alignment in block copolymer nanocomposites is studied using External Potential Dynamics (EPD) method, wherein an equivalent evolution equation for potential fields is solved instead of conservation equation for the monomer segments. The dynamics study reveals an interesting interplay of nanoparticle mobility, dipolar interaction strength and nanoparticle-polymer interaction strength on the rate of alignment of domains.
Author: Vibha Kalra Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Advances in materials synthesis and fabrication techniques allow an unprecedented control over the creation of novel building blocks such as polymers and particles. The first principle for effective utilization of these building blocks is to create techniques to control their assembly at length scales ranging from nanoscale to macroscopic scale. Hierarchically structured materials have been fabricated by combining the functionalities of block copolymer nanocomposites with the advantages of nanofibers. First, a novel methodology to synthesize block copolymer nanofibers with ordered self assembly has been developed, followed by a systematic study on how this self assembly is altered due to the cylindrical confinement of nanofibers. Then, this self assembly in nanofibers is used as a template to control the spatial distribution of functional nanoparticles. One of the key findings of this work is that a much larger fraction of nanoparticles can be placed (without agglomeration) within nanofibers compared to films of the same materials. To zero in on the mechanism and to understand the thermodynamic and kinetic processes that drive nanoparticle placement in block copolymers during deformation (an important constituent of electrospinning nanofiber fabrication process), coarse grained molecular dynamics simulations have been conducted. Here, the effect of shear flow on different types of block copolymer/nanoparticle systems has been first studied, followed by a study on effect of elongational flow on various block copolymer nanocomposite systems.
Author: Valeriy V. Ginzburg Publisher: Springer Nature ISBN: 3030604438 Category : Technology & Engineering Languages : en Pages : 330
Book Description
This edited volume brings together the state of the art in polymer nanocomposite theory and modeling, creating a roadmap for scientists and engineers seeking to design new advanced materials. The book opens with a review of molecular and mesoscale models predicting equilibrium and non-equilibrium nanoscale structure of hybrid materials as a function of composition and, especially, filler types. Subsequent chapters cover the methods and analyses used for describing the dynamics of nanocomposites and their mechanical and physical properties. Dedicated chapters present best practices for predicting materials properties of practical interest, including thermal and electrical conductivity, optical properties, barrier properties, and flammability. Each chapter is written by leading academic and industrial scientists working in each respective sub-field. The overview of modeling methodology combined with detailed examples of property predictions for specific systems will make this book useful for academic and industrial practitioners alike.
Author: Ian W. Hamley Publisher: Oxford University Press on Demand ISBN: 9780198502180 Category : Science Languages : en Pages : 424
Book Description
This comprehensive and systematic text is the first of its kind to deal with the fundamental physics underlying the remarkable structural and dynamical properties of block copolymers. It provides the polymer scientist and technologist with a firm grounding in the principles underlying the wide applications of these important materials. It also highlights the intrinsically fascinating properties of block copolymers, such as nanoscale self-assembly in bulk and two-dimensions. The first textof its kind on the subject since the mid-1980s, this book stands alone - previous texts have focused on the chemical and material properties of block copolymers. During the last decade, there have been major developments in the field, and these experimental and theoretical advances are discussed in depth. Topics covered include: the thermodynamics and dynamics of block copolymer melts, block copolymers in dilute, semidilute and concentrated solutions, the structure of crystalline block copolymers and block copolymers in blends with other polymers. This informative book is essential to the polymer physics and materials science researcher in industry and academia, and postgraduates in related fields. Final year undergraduate students in chemistry, physics and materials science will also find this book useful as a reference text.
Author: Frank Abdi Publisher: CRC Press ISBN: 9814669032 Category : Science Languages : en Pages : 509
Book Description
These days, advanced multiscale hybrid materials are being produced in the industry, studied by universities, and used in several applications. Unlike for macromaterials, it is difficult to obtain the physical, mechanical, electrical, and thermal properties of nanomaterials because of the scale. Designers, however, must have knowledge of these properties to perform any finite element analysis or durability and damage tolerance analysis. This is the book that brings this knowledge within easy reach. What makes the book unique is the fact that its approach that combines multiscale multiphysics and statistical analysis with multiscale progressive failure analysis. The combination gives a very powerful tool for minimizing tests, improving accuracy, and understanding the effect of the statistical nature of materials, in addition to the mechanics of advanced multiscale materials, all the way to failure. The book focuses on obtaining valid mechanical properties of nanocomposite materials by accurate prediction and observed physical tests, as well as by evaluation of test anomalies of advanced multiscale nanocomposites containing nanoparticles of different shapes, such as chopped fiber, spherical, and platelet, in polymeric, ceramic, and metallic materials. The prediction capability covers delamination, fracture toughness, impact resistance, conductivity, and fire resistance of nanocomposites. The methodology employs a high-fidelity procedure backed with comparison of predictions with test data for various types of static, fatigue, dynamic, and crack growth problems. Using the proposed approach, a good correlation between the simulation and experimental data is established.
Author: Massimo Lazzari Publisher: Wiley-VCH ISBN: 3527610561 Category : Technology & Engineering Languages : en Pages : 447
Book Description
This first book to take a detailed look at one of the key focal points where nanotechnology and polymers meet provides both an introductory view for beginners as well as in-depth knowledge for specialists in the various research areas involved. It investigates all types of application for block copolymers: as tools for fabricating other nanomaterials, as structural components in hybrid materials and nanocomposites, and as functional materials. The multidisciplinary approach covers all stages from chemical synthesis and characterization, presenting applications from physics and chemistry to biology and medicine, such as micro- and nanolithography, membranes, optical labeling, drug delivery, as well as sensory and analytical uses.
Author: Sabu Thomas Publisher: William Andrew ISBN: 0323413919 Category : Technology & Engineering Languages : en Pages : 500
Book Description
Spectroscopy of Polymer Nanocomposites covers all aspects of the spectroscopic characterization of polymer nanocomposites. More than 25 spectroscopy characterization techniques – almost all used in materials science – are treated in the book, with discussion of their potentialities and limitations. By comparing the techniques with each other and presenting the techniques together with their specific application areas, the book provides scientists and engineers the information needed for solving specific problems and choosing the right technique for analyzing the material structure. From this, the dispersion structure of fillers, property relations and filler-polymer interactions can be determined, and, ultimately, the right materials can be chosen for the right applications. Besides the techniques and structure-property relations, aspects covered include: phase segregation of filler particles, filler agglomeration and deagglomeration, filler dispersion, filler-polymer interactions, surfaces and interfaces. The book also examines recent developments, as well as unresolved issues and new challenges, in the characterization of surfaces and interfaces in polymer nanocomposites. This handpicked selection of topics, and the combined expertise of contributors from industry, academia, government and private research organizations across the globe, make this survey an outstanding reference source for anyone involved in the field of polymer nanocomposites in academia or industry. - Provides comprehensive coverage of spectroscopy techniques for analyzing polymer nanocomposites - Enables researchers and engineers to choose the right technique and make better materials decisions in research and a range of industries - Presents the fundamentals, information on structure-property relations, and all other aspects relevant for understanding spectroscopic analyses of nanoreinforced polymers and their applications
Author: 
Author: 
Author: Galder Kortaberria
Author: Galder Kortaberria
Author: Vinay Raman
Author: Vibha Kalra
Author: Valeriy V. Ginzburg
Author: Ian W. Hamley
Author: Frank Abdi
Author: Massimo Lazzari
Author: Sabu Thomas