The articles in this book summarize the work presented at the final workshop of the COST (European Cooperation in the Field of Scientific and Technical Research) Action on Molecular materials and Functional polymers f...
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ISBN:
(数字)9783709162767
ISBN:
(纸本)9783211835975
The articles in this book summarize the work presented at the final workshop of the COST (European Cooperation in the Field of Scientific and Technical Research) Action on Molecular materials and Functional polymers for Advanced Devices, which was held in June 2000 in Patras, Greece. The collection gives an excellent overview of the state-of-the-art in this field and the progress made by the coordinated research projects. The results range over the synthesis, physical properties, and applications of molecular materials (nanotubes, fullerenes, phthalocyanines), inorganic and inorganic-organic hybrid materials, and functional polymers (electronic conduction, photoluminiscence, optical storage, photovoltaic devices).
The ability to behave in a fluidlike manner fundamentally separates thermoset and thermoplastic polymers. Bridging this divide, covalent adaptable networks (CANs) structurally resemble thermosets with permanent covale...
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The ability to behave in a fluidlike manner fundamentally separates thermoset and thermoplastic polymers. Bridging this divide, covalent adaptable networks (CANs) structurally resemble thermosets with permanent covalent crosslinks but are able to flow in a manner that resembles thermoplastic behavior only when a dynamic chemical reaction is active. As a consequence, the rheological behavior of CANs becomes intrinsically tied to the dynamic reaction kinetics and the stimuli that are used to trigger those, including temperature, light, and chemical stimuli, providing unprecedented control over viscoelastic properties. CANs represent a highly capable material that serves as a powerful tool to improve mechanical properties and processing in a wide variety of polymer applications, including composites, hydrogels, and shape-memory polymers. This review aims to highlight the enabling material properties of CANs and the applied fields where the CAN concept has been embraced.
This investigation provides the first reported viscosity measurements on cholesteryl myristate. Viscosities were measured as a function of both temperature and shear over temperatures corresponding to the isotropic li...
This investigation provides the first reported viscosity measurements on cholesteryl myristate. Viscosities were measured as a function of both temperature and shear over temperatures corresponding to the isotropic liquid, the cholesteric mesophase, and the smectic mesophase. The myristate ester was chosen for study because its multiple phase transitions have been previously shown to be reproducible. The phases also persist over relatively long temperature ranges. The viscosity measurements were made at lower shear rates than previously reported for esters of cholesterol by using a Weissenberg Rheogoniometer. These are the first cone-and-plate viscosity measurements reported for any esters of cholesterol. The shear rates in this cone-and-plate viscometer are homogeneous and variable. The results show large breaks in viscosity behavior at the independently-measured thermodynamic transitions between the crystal, smectic, cholesteric, and isotropic states. Viscosities for the isotropic state are Newtonian throughout. The viscosities for both the cholesteric and smectic mesophases are prominently non-Newtonian with a sharp transition between the two. This is the first time a change in rheology has been reported at a smectic-cholesteric transition. A prominent viscosity maximum is observed near the cholesteric-isotropic transition which depends on shear rate and perhaps on time of shearing.
This volume contains papers presented at the Second Symposium on Ordered Fluids and Liquid Crystals held at the 158th National Meeting of the American Chemical Society, New York, Sep tember, 1969. The Symposium ...
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ISBN:
(数字)9781468482140
ISBN:
(纸本)9781468482164
This volume contains papers presented at the Second Symposium on Ordered Fluids and Liquid Crystals held at the 158th National Meeting of the American Chemical Society, New York, Sep tember, 1969. The Symposium was sponsored by the Division of Colloid and Surface Chemistry. The proceedings for the first symposium on this subject were published by the American Chemical Society in the Advances in Chemistry Series. In the preface to the volume for the first meet ing held four years ago, we noted that research on liquid crystals had gone through tremendous fluctuations, with peaks of activity around 1900 and again in the early 1930's. The present period of high activity which started about 1960 has continued to exhibit acceleration. The reason for the persistent growth in the field is due to the increasing recognition of the important role played by liquid crystals in both biological systems and in items of commerce as diverse as detergents and electronic components. Addi tionally, more powerful and sophisticated instrumentation is pro viding a basis for understanding the properties of the liquid crystalline state as weIl as yielding inc~s~ve tests for the theories of mesophase structure which are only now reaching astate of maturity. Julian F. Johnson Roger S. Porter v CONTENTS Thermal Phase Transitions in Biomembranes • . • • • • • . • • 1 Joseph M. Steim Conditions of Stability for Liquid-Crystalline Phospholipid Membranes .
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