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Author: Wenda Wang
Publisher:
ISBN:
Category : Carbon nanotubes
Languages : en
Pages : 370
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Book Description
Liquid/liquid interface, either flat or curved, is a unique template for studying self-assembly of a variety of nanomaterials such as nanoparticles and nanorods. The resultant monolayer films can be ordered or disordered depending on the regularity of the nanomaterials. Integration of nanoparticles into two-dimensional structure leads to intriguing collective properties of the nanoparticles. Crystallization can also be guided by liquid/liquid interface. Due to the particular shape of the interface, crystallization can happen in a different manner comparing to the normal solution crystallization. In this dissertation, liquid/liquid interface is employed to guide the crystallization of polymers, mainly focusing on using curved liquid/liquid interface. Due to the unique shape of the interface and feasibility to control the curvature, polymer crystallization can take place in different manner and lead to the formation of curved or vesicular crystals. Curved liquid/liquid interface is typically created through o/w emulsions. With the presence of surfactant, the emulsions are controlled to be stable at least for the polymer crystallization periods. The difference to normal solution crystallization is: the nuclei will diffuse to the curved interface due to the Pickering effect and guide the crystallization along the curved liquid/liquid interface. If the supercooling can be controlled to be very small, crystal growth in the bulk droplets can be avoided. The advantages of this strategy are: 1) the formation process of vesicular type crystals can be monitored by controlling the polymer supply; 2) curved crystals, bowl-like structures and enclosed capsules can be easily obtained comparing to the self-assembly method for vesicle formation; 3) the obtained vesicles will be made of polymer crystals, which will possess the extraordinary mechanical properties. Based on the nucleation type, this dissertation is divided into two parts. The first part is focused on the self-assembly behavior of single-walled carbon nanotubes (SWCNTs) at curved liquid/liquid interface and the crystallization behavior of polymers at curved liquid/liquid interface while SWCNTs in presence. A few crystalline polymers, such as polyethylene (PE), poly(l-lactic acid) (PLLA), and poly(3-hexylthiophene-2,5-diyl) (P3HT), and water/oil systems were used to study the behavior. The formation of nano speckle structure is a crystallization-driven process due to heterogeneous nucleation and crystal growth of polymers at curved liquid/liquid interface. The second part deals with the homogeneous nucleation and crystal growth at curved liquid/liquid interface. Both PE and PLLA were used to conduct the study. For PE, 1,2-dichlorobenzene (DCB), water, and sodium dodecylsulfate (SDS) were used for the emulsion system. The emulsification system for PLLA is p-xylene, water, and hexadecyltrimethylammonium bromide (CTAB). Surfactant concentration can be employed to control the droplet size, thus controlling the final crystal vesicle's size. By controlling the initial polymer concentration, crystal shells with different morphology, such as curved crystal, bowl-like crystals, and crystal vesicles (named lamellaesome) can be obtained. The formation of these unique structures was templated by the curved interface. The formation process and detailed crystal structure are analyzed based on electron diffraction data from different sized lamellaesomes. Mechanical properties of the crystal vesicles and their encapsulation abilities will be discussed. At the end of this dissertation, a summary of my work and future outlook will be given.
Author: Wenda Wang
Publisher:
ISBN:
Category : Carbon nanotubes
Languages : en
Pages : 370
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Book Description
Liquid/liquid interface, either flat or curved, is a unique template for studying self-assembly of a variety of nanomaterials such as nanoparticles and nanorods. The resultant monolayer films can be ordered or disordered depending on the regularity of the nanomaterials. Integration of nanoparticles into two-dimensional structure leads to intriguing collective properties of the nanoparticles. Crystallization can also be guided by liquid/liquid interface. Due to the particular shape of the interface, crystallization can happen in a different manner comparing to the normal solution crystallization. In this dissertation, liquid/liquid interface is employed to guide the crystallization of polymers, mainly focusing on using curved liquid/liquid interface. Due to the unique shape of the interface and feasibility to control the curvature, polymer crystallization can take place in different manner and lead to the formation of curved or vesicular crystals. Curved liquid/liquid interface is typically created through o/w emulsions. With the presence of surfactant, the emulsions are controlled to be stable at least for the polymer crystallization periods. The difference to normal solution crystallization is: the nuclei will diffuse to the curved interface due to the Pickering effect and guide the crystallization along the curved liquid/liquid interface. If the supercooling can be controlled to be very small, crystal growth in the bulk droplets can be avoided. The advantages of this strategy are: 1) the formation process of vesicular type crystals can be monitored by controlling the polymer supply; 2) curved crystals, bowl-like structures and enclosed capsules can be easily obtained comparing to the self-assembly method for vesicle formation; 3) the obtained vesicles will be made of polymer crystals, which will possess the extraordinary mechanical properties. Based on the nucleation type, this dissertation is divided into two parts. The first part is focused on the self-assembly behavior of single-walled carbon nanotubes (SWCNTs) at curved liquid/liquid interface and the crystallization behavior of polymers at curved liquid/liquid interface while SWCNTs in presence. A few crystalline polymers, such as polyethylene (PE), poly(l-lactic acid) (PLLA), and poly(3-hexylthiophene-2,5-diyl) (P3HT), and water/oil systems were used to study the behavior. The formation of nano speckle structure is a crystallization-driven process due to heterogeneous nucleation and crystal growth of polymers at curved liquid/liquid interface. The second part deals with the homogeneous nucleation and crystal growth at curved liquid/liquid interface. Both PE and PLLA were used to conduct the study. For PE, 1,2-dichlorobenzene (DCB), water, and sodium dodecylsulfate (SDS) were used for the emulsion system. The emulsification system for PLLA is p-xylene, water, and hexadecyltrimethylammonium bromide (CTAB). Surfactant concentration can be employed to control the droplet size, thus controlling the final crystal vesicle's size. By controlling the initial polymer concentration, crystal shells with different morphology, such as curved crystal, bowl-like crystals, and crystal vesicles (named lamellaesome) can be obtained. The formation of these unique structures was templated by the curved interface. The formation process and detailed crystal structure are analyzed based on electron diffraction data from different sized lamellaesomes. Mechanical properties of the crystal vesicles and their encapsulation abilities will be discussed. At the end of this dissertation, a summary of my work and future outlook will be given.
Author: Hao Qi
Publisher:
ISBN:
Category : Crystallization
Languages : en
Pages : 356
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Book Description
Liquid-liquid and liquid-air interfaces are crucial to study amphiphile and colloidal self-assembly. Crystallization of polymers can also be regarded as a self-assembly process. In this dissertation, liquid interfaces are employed to direct polymer crystallization. Due to the particular interaction between the polymer chain and the interface, polymer crystallizations are confined in certain manners. According to the shape of the interface, this dissertation is divided into two parts, flat liquid-liquid interface and curved liquid-liquid interface. A flat water/pentyl acetate interface was created as a model system to study evaporative crystallization of poly (Îæ-caprolactone) which has carboxylic acid groups on both ends. A millimeter scale uniform polymer single crystal (PSC) film can form at the water/pentyl acetate interface. Due to the asymmetric nature of the liquid-liquid interface, the PSC film exhibit Janus property - a hydrophobic side and a hydrophilic side. Moreover, the effect of polymer chain conformation prior to on crystallization is studied, using PCL with different hydrophobic/hydrophilic ends. By using atomic force microscopy and transmission electron microscopy, terminal structures and temporal evolution of the crystalline films were explored. Different crystallization routes were revealed as a result of different polymer chain conformation. We furthermore proposed a phase diagram to explain different crystallization routes and demonstrated the phase diagram can be regulated via tuning polymer chain conformation at the liquid-liquid interface. Next, we demonstrated evaporative crystallization of PCL on a curved template will result in a curved lamella. The curved template was from PCL-b-PAA block copolymer Janus plates which can undergo a pH-triggered 2D to 3D shape transformation, due to the controlled degree of PAA ionization. As evidenced by selected area electron diffraction experiments, PCL crystalline domains arranged themselves into tortoise shell-like domain packing to accommodate the curvature. Curved space is intrinsically incommensurate with 3D translational symmetry. However, soft materials, including colloids, amphiphiles and block copolymers can form structures depicting curved surface/interfaces through self-assembly or directed assembly. It is therefore intriguing to study how polymer crystallization takes place in a curved space. Curve liquid-liquid interface was created through oil in water emulsion. Amphiphilic PLLA-b-PEG block copolymer was used as both surfactant to stabilize the emulsion and crystallization material. We demonstrated emulsion crystallization method can effectively confine and direct PLLA crystallization at curved emulsion droplet interface. Temporal evolution revealed there is only one nucleus per droplet and nucleation occurred at the interface because the crystalline block is confined at the liquid/liquid interface prior to crystallization. With the purpose to apply the obtained block copolymer crystalsomes (BCCs) for in-vivo study, we fabricated fully enclosed BCCs within 200 nm using PLLA-b-PEG/toluene and water emulsion system. Detailed structural characterization demonstrated the emulsion solution crystallization method is efficient to guide polymer chain folding into uniform crystalline packing at curved liquid-liquid interface to form single-crystal-like structure. As a new type of block copolymer ensemble, BCCs exhibit superior mechanical stability and extremely long circulation performance in vivo.
Author: Sabu Thomas
Publisher: Elsevier
ISBN: 0128094311
Category : Technology & Engineering
Languages : en
Pages : 612
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Book Description
Crystallization in Multiphase Polymer Systems is the first book that explains in depth the crystallization behavior of multiphase polymer systems. Polymeric structures are more complex in nature than other material structures due to their significant structural disorder. Most of the polymers used today are semicrystalline, and the subject of crystallization is still one of the major issues relating to the performance of semicrystalline polymers in the modern polymer industry. The study of the crystallization processes, crystalline morphologies and other phase transitions is of great significance for the understanding the structure-property relationships of these systems. Crystallization in block copolymers, miscible blends, immiscible blends, and polymer composites and nanocomposites is thoroughly discussed and represents the core coverage of this book. The book critically analyzes the kinetics of nucleation and growth process of the crystalline phases in multi-component polymer systems in different length scales, from macro to nanoscale. Various experimental techniques used for the characterization of polymer crystallization process are discussed. Written by experts in the field of polymer crystallization, this book is a unique source and enables professionals and students to understand crystallization behavior in multiphase polymer systems such as block copolymers, polymer blends, composites and nanocomposites. Covers crystallization of multiphase polymer systems, including copolymers, blends and nanocomposites Features comprehensive, detailed information about the basic research, practical applications and new developments for these polymeric materials Analyzes the kinetics of nucleation and growth process of the crystalline phases in multi-component polymer systems in different length scales, from macro to nanoscale
Author: Magda A. El-Nokaly
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 388
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Book Description
Very Good,No Highlights or Markup,all pages are intact.
Author: Giuseppe Allegra
Publisher: Springer Science & Business Media
ISBN: 9783540282808
Category : Technology & Engineering
Languages : en
Pages : 328
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Book Description
With contributions by numerous experts
Author: N.A. Platé
Publisher: Springer Science & Business Media
ISBN: 9780306442193
Category : Science
Languages : en
Pages : 452
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Book Description
Drawing a picture of the current situation of this new field, this volume both summarizes the past achievements and analyzes the present unsolved problems.
Author: Division on Engineering and Physical Sciences
Publisher: National Academies Press
ISBN: 0309042313
Category : Technology & Engineering
Languages : en
Pages : 121
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Book Description
Author: David C. Bassett
Publisher: Springer Science & Business Media
ISBN: 9400913419
Category : Technology & Engineering
Languages : en
Pages : 351
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Book Description
Modern society makes increasing demands for novelty in materials and their properties which are ever more exacting. Crystalline polymers are in the forefront of this demand and improvements are constantly occurring across the entire range from existing materials of high tonnage to novel materials with application in information technology. The developments recorded in this volume reflect this situation. Chapter 1 is a comprehensive review of the polymer PHB, poly(hydroxybutyrate), which is new to industrial manufacturing but is a naturally occurring substance. It has potentially valuable properties but has excited interest especially because it is biodegradable. It may, therefore, provide one means of reducing environmental pollution. Improvements in existing materials, beyond those which are ob tainable by optimization of known variables, are most likely to come from understanding of structure-property relationships. Polymer is able to make effective science has now reached the stage where it synthesis of information from complementary techniques, leading to rapidly deepening understanding. Chapters 2, 3 and 4 are all con cerned with technical developments which are contributing substan tially to this synthesis. The possibilities of electron microscopy, specifically the characterization of lamellar microstructure, have been transformed by permanganic etching. Now real organization (which can be very different from what had previously been inferred) can be used as a basis for explaining polymeric properties. In Chapter 3, Mitchell and Windle give a critical account of the assessment of orientation in liquid crystalline polymers, a rapidly developing new field in which they have played a leading part.
Author: Francesco Paolo La Mantia
Publisher: CRC Press
ISBN: 9780877629603
Category : Technology & Engineering
Languages : en
Pages : 196
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Book Description
In recent years, studies by both industry and academic researchers have opened the door to improving performance and reducing costs of these new materials. The particular structure and morphology of LCPs, as well as their peculiar rheological behavior, have stimulated researchers to develop new theoretical models and new characterization and processing techniques to more fully understand and utilize LCPs. Although the scientific literature is very rich in data on the synthetic techniques and on the relations between structure and phase behavior of these new polymers, the understanding of the rheological and processing aspects is still far from satisfactory-particularly in the case of LCP blends. In fact, although an appreciable number of patents and scientific papers have appeared describing the phase behavior, the rheology, and the mechanical properties of many of these polyblends, several aspects of the relations between processing and morphology, and between morphology and properties of these materials are still obscure or even controversial. Now, this new book, written by leading researchers, provides an up-to-date guide and reference to the processing, rheology and applications of pure LCPs and LCP blends. The book concisely reviews the synthetic procedures for the production of LCPs and discusses the rheological behavior and processing methods. Plus, the book examines present and future applications areas of LCPs and LCP blends.
Author: Alexandre Blumstein
Publisher: Elsevier
ISBN: 0323154840
Category : Science
Languages : en
Pages : 349
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Book Description
Liquid Crystalline Order in Polymers examines the topic of liquid crystalline order in systems containing rigid synthetic macromolecular chains. Each chapter of the book provides a review of one important area of the field. Chapter 1 discusses scattering in polymer systems with liquid crystalline order. It also introduces the field of liquid crystals. Chapter 2 treats the origin of liquid crystalline order in macromolecules by describing the in-depth study of conformation of such macromolecules in their unassociated state. The chapters that follow describe successively the liquid crystalline order in polymers with mesogenic side groups and rigid backbones, in polypeptides, and in block copolymers. Chapter 7 discusses the rheology of such systems. The last two chapters examine liquid crystalline order in biological materials and mesomorphic order in the realm of polymers with inorganic backbones. This book is intended to provide the polymer scientist, the materials scientist, and the biologist with a valuable source of information.
