Download or read book Synthesis of Helical Polycarbodiimides and Their Properties written by Galappaththi De Silva and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polycarbodiimides are a relatively new class of synthetic macromolecules. Their helical conformation and tunable pendant groups made them special class of polymer which displayed interesting properties. We evaluated the properties of carbodiimide polymers consisting of long chain branched aliphatic groups. Newly synthesized helical polycarbodiimides with branched aliphatic side chains were introduced to evaluate the effect of these branched alkyl chains on the properties of the polymers. These polymers displayed different thermal and lyotropic liquid crystalline properties depending on the amount of branched side chains attached to the polymer backbone. The synthesis of water-soluble polymers and their potential applications were extensively studied. The significant properties of the water-soluble polycarbodiimides were evaluated. The pH dependent behavior of self-assembled polycarbodiimides were studied. This could be a potential candidate for the nano carrier applications. In addition, we investigated biomimetic polycarbodiimides which exhibited antimicrobial and cytotoxic properties.
Download or read book Synthesis and Characterization of Helical Polycarbodiimide Copolymers Containing Long chain Branched kinked Alkyl Groups written by Michael W. Duff and published by . This book was released on 2015 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polycarbodiimides are a class of helical rigid-rod polymers with a host of interesting properties and potential applications. One polycarbodiimides in particular, poly(N-naphthyl-N'-octadecylcarbodiimide) (PNOC), has been studied extensively and is notable for its reversible solvent-dependent chiroptical switching behavior as well as its potential application as part of an "electronic nose." It is not yet fully understood what role the octadecyl side chains play in interesting the properties of this polymer. In this work, branched and kinked alkyl groups were introduced in place of the octadecyl side chain via the synthesis of several copolymers and the effect of these changes on the properties of the polymers was evaluated. It was found that copolymers containing branched and kinked groups in place of octadecyl side chains exhibit different thermal characteristics as well as unique thin film morphologies in different solvents, however the switching behavior and chirality of the pure polymer is retained.
Download or read book Synthesis and Investigation of Chiral Polycarbodiimides with Reversible Dynamic Properties written by Justin Glenn Kennemur and published by . This book was released on 2010 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: Keywords: polymer, helical, circular dichroism, polycarbodiimide, polyguanidine, polarimetry, conformational change.
Download or read book Structure property Relationships of Helical Polycarbodiimides and Nanostructured Siloxanes with Helical Fluoroalkyl Substituents written by Raymond Campos and published by . This book was released on 2015 with total page 566 pages. Available in PDF, EPUB and Kindle. Book excerpt: The helical motif is ubiquitous in nature and in everyday life, both on the micro- and macroscale. The following research covers the synthesis and structure-property relationships of two macromolecules possessing core-shell architectures with helical motifs in their structure. The well-defined shape/size of macromolecules studied resulted in unique self-assembly behavior and physical properties. The first chapter introduces the structural features, nomenclature, and structure-property relationships of both helical polymers and fluoroalkyl helices. Chapters 2-4 introduce the chiroptical switching of regioregular polycarbodiimides (RR-PCD) in solution, cover the solid-state conformational switching of RR-PCD's and the dynamic wettability of RR-PCD's. Studies covered in these chapters reveal that the conformational switching of certain RR-PCD's in dilute solution also occurs in the solid state. The solid-state characterization of conformational switching suggests that the confined, comb-like structure promotes crystallization of n-alkyl substituents near the backbone of RR-PCD's. The solid-state conformational switching of RR-PCD's can be dynamically monitored both spectroscopically and on the bulk scale. The principles and materials developed are demonstrated through molecular sensing of volatile organic compounds using ATR-FTIR transduction and through liquid droplet actuation. Chapter 5 covers the synthesis of fluoroalkyl-substituted polyhedral oligomeric silsesquioxane (fluoroPOSS) compounds. Fully-condensed, Oh-(H2F8)8T8 fluoroPOSS compound is derived into either a mixture of cages or into an incompletely condensed intermediate for synthesizing reactive POSS compounds as polymer grafts and monomers. Breaking the symmetry of fluoroPOSS through cage redistribution reduced surface assembly and oleophobicity. The synthesis of fluoropolymers derived from fluoro-olefins is covered in chapter 6. Semi-fluorinated aryl ether polymers were synthesized from the cyclodimerization of trifluorovinyl ethers (TFVE) and the nucleophilic substitution of fluoro-olefins with phenoxides. Chapter 6 is focused on the synthesis of AB-type monomers for the preparation of perfluorocycloalkene (PFCA) aryl ether polymers. These semi-fluorinated polymers were designed for the future study of surface migration/ reorganization of fluoroPOSS blends and copolymers.
Download or read book Unique Architectures Built on Chiral Polycarbodiimides written by Dumindika Aththanayake Siriwardane and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Chapter one introduces the basic synthetic routes for ureas, carbodiimide monomers, polymers and strategies utilized for screw sense polymerization to achieve control chiral architectures. It also presents a comprehensive review of the most recent developments in post-polymerization modifications, properties of polycarbodiimides and their potential applications in the material sciences and bio-medical field. Chapter two illustrates the synthesis of novel Ni(II) initiators for screw sense polymerization of chiral monomers and it explained Ni(II) mediated “living” polymerization used in the synthesis of multi-arm star polymers. This star and its linear analogs have been used to conduct kinetic of polymerization and solvent tunable self-assembly behavior studies. Chapter three describes the unusual observation made years ago, that a particular chiral polymer (predominantly P or M helices) synthesized by using chiral BINOL-Ti(IV) catalysts which show specific racemization behavior when heated. This behavior was unique in more than 150 different carbodiimides we have polymerized to date. We postulated that it was due to stereocomplexation formed via racemization between two opposite helical sense. Different characterization techniques and molecular models were employed to investigate this particular observation. By enhancing helical, polycarbodiimide architectures, chapter four introduces the synthesis of hairy polymers which showed micellization in an aqueous medium. These types of amphiphilic graft co-polymers can be utilized in drug delivery applications. The synthesis and optical switching behavior of UV and thermo responsive polycarbodiimides have been illustrated in chapter five. Properties of the polymer were altered through the isomerization behavior, such as its topology and liquid crystallinity. The synthesis of various chiral designs build upon polycarbodiimide helical frameworks are also included to pursue possible future projects.
Download or read book The Synthesis and Characterization of Polycarbodiimides written by Andrew Albert Goodwin and published by . This book was released on 1996 with total page 662 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis Characterization and Applications of Helical Polycarbodiimide Homopolymers and Copolymers written by James Fredrick Reuther and published by . This book was released on 2015 with total page 454 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigation of Helicity of Water Soluble Polycarbodiimides and Preparation of Nano Particles with Amphiphilic Polycarbodiimides written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: As a helical polymer, polycarbodiimides have been investigated for a period of time. But few water soluble polycarbodiimides had been synthesized and characterized. Since solubility of polycarbodiimides can be controlled by their side arms, achiral or chiral carbodiimides bearing hydrophilic tertiary amino group have been prepared. Single-handed sense hydrophilic polycarbodiimides were prepared from chiral monomers by achiral metal catalyst or from achiral monomers by chiral catalyst to give polycarbodiimides with predominately helical sense. The water solubility of these polycarbodiimides bearing tertiary amino groups is improved when they are methylated by methyl camphorsulfornic acid ester. Configurational and conformational predominately helical polycarbodiimides behave with different way when they are heated. For the former case, the polymers rearrange to their Thermodynamic Control Conformation (TCC) from Kinetic Control Conformation (KCC); for the later one, the polymer became racemic when annealed. The activation energies for the conformational change can be determined through Arrhenius plot analysis. Compared to the neutral polycarbodiimides bearing tertiary amino groups, the corresponding ionic polymers have higher activation energies. Helical induction of the water-soluble polycarbodiimides also has been investigated. CD spectrum was run for both the neutral and ionic polycarbodiimides and peptide mimics were found. In addition to the hydrophilic monomers, chiral or achiral hydrophobic carbodiimides were also synthesized and polymerized. Through living polymerizations, the amphiphilic polycarbodiimides were prepared from metal catalysts. Crew-cut nanoparticles have been prepared through a phase inversion method. Different conditions have been tried to achieve nano particles with different morphologies and sizes. In the nano particle preparation, water amount, acid amount and molecular weight play important roles in preparation of nano particles. TEM was u.
Download or read book Liquid Crystals written by and published by . This book was released on 2002 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fire resistant Materials written by Richard E. Lyon and published by . This book was released on 1998 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report details the research being conducted by the Federal Aviation Administration (FAA) to develop fire-safe cabin materials for commercial aircraft; The objective of the Fire-Resistant Materials program is to eliminate burning cabin materials as a cause of death in aircraft accidents. Long-term activities include the synthesis of new, thermally stable, low fuel value organic and inorganic polymer systems. The synthesis effort is supported by fundamental research to understand polymer combustion and fire resistance mechanisms using numerical and analytic modeling and the development of new characterization techniques. Aircraft materials which are targeted for upgraded fire resistance are (1) thermoset resins for interior decorative panels, secondary composites, and adhesives; (2) thermoplastics for decorative facings, telecommunication equipment, passenger service units, molded seat parts, transparencies, and electrical wiring; (3) textile fibers for upholstery, carpets, decorative murals, tapestries; and (4) elastomers/rubber for seat cushions, pillows, and sealants. During the first 2 years of the program (1995- 1996) we have made significant progress in achieving our interim goal of a 50 percent reduction in the heat release rate of cabin materials by 2005 and zero heat release rate cabin materials by 2018 with respect to the 1996 baseline for new aircraft. A previous report, Fire-Resistant Materials: Research Overview, DOT/FAA/AR-97/99, summarizes the background and technical objectives of the program and serves as an introduction to the present document.
Download or read book Materials Chirality written by Mark M. Green and published by John Wiley & Sons. This book was released on 2004-05-07 with total page 625 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dieser Sonderband der Reihe "Topics in Stereochemistry" beschäftigt sich mit der Chiralität von Werkstoffen und der Bedeutung der Stereochemie für bestimmte Polymere, Flüssigkristalle und andere spezielle Materialien. Die Grundlage dafür bilden die ausführlich dargestellten Prinzipien der organischen Stereochemie. Das aktuellste derzeit erhältliche Buch zur Chiralität!
Download or read book Amplification of Chirality written by Kenso Soai and published by Springer Science & Business Media. This book was released on 2009-11-04 with total page 211 pages. Available in PDF, EPUB and Kindle. Book excerpt: Amplification of Chirality presents critical reviews of the present position and future trends in modern chemical research. The book contains short and concise reports on chemistry. Each is written by the world renowned experts. Still valid and useful after 5 or 10 years, more information as well as the electronic version of the whole content available at: springerlink.com.
Download or read book Issues in Materials and Manufacturing Research 2011 Edition written by and published by ScholarlyEditions. This book was released on 2012-01-09 with total page 11119 pages. Available in PDF, EPUB and Kindle. Book excerpt: Issues in Materials and Manufacturing Research: 2011 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about Materials and Manufacturing Research. The editors have built Issues in Materials and Manufacturing Research: 2011 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Materials and Manufacturing Research in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Materials and Manufacturing Research: 2011 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.
Download or read book Investigation of Helicity of Water Soluble Polycarbodiimides and Preparation of Nano Particles from Amphiphilic Polycarbodiimides written by Haibo Li and published by . This book was released on 2006 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: Keywords: nano particles, helical polymer, water soluble polymer.
Download or read book Papers Presented at the Meeting written by American Chemical Society. Division of Polymer Chemistry and published by . This book was released on 1997 with total page 732 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Bioinspiration and Biomimicry in Chemistry written by Gerhard Swiegers and published by John Wiley & Sons. This book was released on 2012-09-17 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt: Can we emulate nature's technology in chemistry? Through billions of years of evolution, Nature has generated some remarkable systems and substances that have made life on earth what it is today. Increasingly, scientists are seeking to mimic Nature's systems and processes in the lab in order to harness the power of Nature for the benefit of society. Bioinspiration and Biomimicry in Chemistry explores the chemistry of Nature and how we can replicate what Nature does in abiological settings. Specifically, the book focuses on wholly artificial, man-made systems that employ or are inspired by principles of Nature, but which do not use materials of biological origin. Beginning with a general overview of the concept of bioinspiration and biomimicry in chemistry, the book tackles such topics as: Bioinspired molecular machines Bioinspired catalysis Biomimetic amphiphiles and vesicles Biomimetic principles in macromolecular science Biomimetic cavities and bioinspired receptors Biomimicry in organic synthesis Written by a team of leading international experts, the contributed chapters collectively lay the groundwork for a new generation of environmentally friendly and sustainable materials, pharmaceuticals, and technologies. Readers will discover the latest advances in our ability to replicate natural systems and materials as well as the many impediments that remain, proving how much we still need to learn about how Nature works. Bioinspiration and Biomimicry in Chemistry is recommended for students and researchers in all realms of chemistry. Addressing how scientists are working to reverse engineer Nature in all areas of chemical research, the book is designed to stimulate new discussion and research in this exciting and promising field.
Download or read book Supramolecular Polymers written by Alberto Ciferri and published by CRC Press. This book was released on 2000-05-04 with total page 678 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Focuses on detailed analysis of the formation and properties of linear, planar, and three-dimensional polymer assemblies stabilized by superamolecular interactions, includes examples of covalently bonded polymers exhibiting novel supra-molecular effects. Clarifies the theoretical basis for the self-assembly of structures."
