Download or read book Synthesis and Ring opening Metathesis Polymerization of Norbornenes Containing Pendent Aromatic and Aliphatic Side Chains written by Andrea L. Edel and published by . This book was released on 1999 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis and Ring opening Metathesis Polymerization of Norbornenes Containing Pendent Aromatic and Aliphatic Side Chains written by and published by . This book was released on 1908 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A series of well-defined polynorbornenes containing pendent aromatic ether or aliphatic side chains have been prepared. Synthesis of the monomeric materials proceeded via initial cyclopentadienyl iron-mediated nucleophilic aromatic substitution reactions and DCC-mediated condensation reactions, followed by removal of the metal moiety via photolytic demetallation. Structural analysis of both the metallated and nonmetallated compounds was accomplished using homo- and heteronuclear correlation spectroscopic techniques as well as IR, MS and C, H elemental analysis. Subsequent ring-opening metathesis polymerization of these building blocks was achieved in the presence of a ruthenium-based catalyst, namely bis(tricyclohexylphosphine)benzylidene ruthenium (IV) dichloride, which liberated the resulting polymeric materials in high conversion of the monomer to the polymer. Gel permeation chromatography of each of the polymers revealed high molecular weights as well as low to narrow polydispersity indices. Thermal analysis of the aromatic ether functionalized polynorbornenes was accomplished using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). These results showed that when the number of aromatic groups pendent to the polymer chain increased (within each polymer repeat unit), a subsequent increase in the thermal stability was noted. TGA of the aliphatic-bridged systems revealed decreased thermal stability as the length of the aliphatic flexible spacer increased. Changing the spacer from a purely methylene-bridged system to one containing a tri(ethylene glycol) chain was found to increase the overall thermal properties of the resulting polymeric material.

Download or read book Ring Opening Metathesis Polymerisation and Related Chemistry written by Ezat Khosravi and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 489 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the last ASI in Turkey in Sept. 1995, the olefin metathesis has made remarkable strong developments with an incredible speed in various directions. New catalyst systems have been developed which have resulted in the synthesis of novel materials. Other fascinating developments have been the new catalysts for stereoselective metathesis and catalysts with considerable functional group tolerance. These new catalysts in addition to Ring Opening Metathesis Polymerisation (ROMP) and Acyclic Diene Metathesis (ADMET) are now powerful tools for Ring Closing Metathesis (RCM) and have found many applications in the synthesis of natural products. A lot of information has been established about all aspects of the olefin metathesis and there is a vast literature concerning the process, covering the initiators, mechanistic features and applications of this reaction in organic and polymer synthesis. The NATO ASI on rd th ROMP and Related Chemistry took place in Polanica-Zdroj, Poland during 3 to 15 Sept. 2000, to highlight the developments in this area and to discuss the prospects and visions for the year 2000 and beyond. The aims of the ASI were: to provide a platform for dissemination of knowledge; to promote communication between people who have a serious interest in this field of chemistry; to help establishing international scientific contacts and to provide an opportunity for the scientists with an appropriate scientific background to learn of recent developments in this field of science. There were 15 lecturers and 67 participants in this NATO ASI.

Download or read book Ring Opening Metathesis Polymerization written by Alexey Lyapkov and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, the olefins metathesis has established itself as a powerful tool for carbon-carbon bonds forming and has found numerous applications in polymer chemistry. One of the important directions of metathesis is the polymerization with cycle opening. A study of new ruthenium catalysts, resistant to the many functional groups effects, has showed the possibility of synthesizing functionalized polymers with unique properties. In this chapter, reactivity and activation parameters of eight different norbornene dicarboxylic acid alkyl esters in the presence of a Hoveyda-Grubbs II catalyst for the ring opening metathesis polymerization were determined by 1H NMR analysis in-situ. The molecules of esters differ in the aliphatic radical structure and the location of the substituent groups. Kinetic studies have shown that effective polymerization constants and activation parameters strongly depend on the monomer structure. It is shown that the elongation of the aliphatic radical does not significantly affect the reactivity, but significantly changes the activation parameters. The branching of the aliphatic radical significantly affects both the reactivity of the corresponding ester and the activation parameters of the polymerization. The position of the substituents in the norbornene ring of the ester also has a significant effect on the activation parameters of metathesis polymerization.

Download or read book Handbook of Metathesis Volume 3 written by Robert H. Grubbs and published by John Wiley & Sons. This book was released on 2015-03-09 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt: The second edition of the "go-to" reference in this field is completely updated and features more than 80% new content, with emphasis on new developments in the field, especially in industrial applications. No other book covers the topic in such a comprehensive manner and in such high quality. Edited by the Nobel laureate R. H. Grubbs and E. Khosravi, Volume 3 of the 3-volume work focusses on polymer synthesis. With a list of contributors that reads like a "Who's-Who" of metathesis, this is an indispensable one-stop reference for chemists in academia and industry. View the set here - http://www.wiley.com/WileyCDA/WileyTitle/productCd-3527334246.html Other available volumes: Volume 1: Catalyst Development and Mechanism, Editors: R. H. Grubbs and A. G. Wenzel - http://www.wiley.com/WileyCDA/WileyTitle/productCd-3527339485.html Volume 2: Applications in Organic Synthesis, Editors: R. H. Grubbs and D. J. O ́Leary - http://www.wiley.com/WileyCDA/WileyTitle/productCd-3527339493.html

Download or read book Design of Functionalized Cyclic Aryl Ethers and Alkenes and Their Subsequent Ring opening Polymerization written by Leslie J. May and published by . This book was released on 2001 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ring-opening polymerization of a variety of cyclic and bicyclic monomers that were prepared via nucleophilic aromatic substitution reactions mediated by the cyclopentadienyliron moiety was explored. The ability to design structurally different monomers using this approach, allowed for the isolation of polymeric materials with different chemical and physical properties. It has been well established that organoiron complexes containing an assortment of functionalities can be prepared using this methodology. A variety of asymmetric cyclic aryl ethers were prepared following reaction of diiron complexes with a dinucleophile. Following cleavage of the metal moieties, the aromatic macrocycles were converted to the corresponding insoluble polyaromatic ethers via ring-opening polymerization in the presence of an anionic initiator. The ring-opening metathesis polymerization of a series of bicyclo[2.2.1]heptenes was also investigated. Two classes of polynorbornenes containing cationic iron moieties within their side chains were synthesized u ing organoiron chemistry, and subsequently polymerized in the presence of ruthenium-based catalyst. The resulting organometallic polynorbornenes, with terminal or lateral side chains displayed excellent solubility and thermal stability.

Download or read book Ring opening Metathesis Polymerization of Cyclopropenes and Ladderenes written by Jessica Kalay Su and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The importance of polymer microstructure is manifested in nature, where the precisely regulated monomer sequence in biomacromolecules enables their controlled folding and assembly to afford vital biological functions. In the pursuit of man-made materials with sophisticated properties, the field of polymer chemistry has developed rapidly to enable the synthesis of polymers with controlled microstructures. Specifically, living polymerization techniques, such as ring-opening metathesis polymerization (ROMP), enable excellent control over polymer molecular weight, composition, and architecture. ROMP is driven primarily by the release of ring strain in cyclic olefin monomers, but surprisingly few studies have been performed on the ROMP of cyclopropenes (CPEs), the most strained monocyclic olefins. In 2015, our group discovered that a class of 1,1-disubstituted CPE undergoes selective single addition to Grubbs third generation catalyst. Monomers which undergo single addition are extremely rare for chain-growth polymerizations and are particularly useful for manipulating the monomer sequence in a polymer. As such, we focused our research efforts on discovering other CPEs that can undergo single addition and uncovering the mechanism and role of their substituents. We have synthesized a library of CPEs with various disubstitution patterns and substituents and systematically investigated their reactivity with Grubbs catalyst. We have found that 1,1-disubstitution of CPE is crucial for both preserving the stability of the propagating chain end and tuning the metathesis reactivity from living polymerization to single addition. The distinct reactivities stemmed from differences in sterics and/or chelation at the Ru alkylidene from C1 substituents after a single CPE ring-opening event, affecting the barrier to propagation. We have utilized the single addition reactivity of CPEs to synthesize alternating copolymers with diverse side chain and backbone functionalities from alternating ROMP of CPE with low-strain cyclic olefins. Recently, we have developed a strategy to precisely place discrete functionalities and side chains via ring-opened CPEs at pre-determined locations along a living ROMP polymer chain, with control over the location and number incorporated. This advance in polymer chemistry opens many exciting opportunities to manipulate the functionalities along well-controlled polymer chains for understanding the effects of their placement and sequence on polymer behaviors, controlling polymer folding/assembly, as well as synthesizing polymers with more complex nonlinear architectures with precision. Our group also recently reported a unique polymechanophore system, polyladderene, that undergoes force-triggered rearrangement into semi-conducting, insoluble polyacetylene. A notable feature in the design was the terminal strained cyclobutene on ladderene that allowed rapid ROMP. We have developed synthetic procedures to prepare triblock copolymers containing mechanically active polyladderene, since block copolymers can self-assemble in solution and bulk and facilitate incorporation of polyladderene with common polymers to impart the dramatic stress-response of polyladderene to diverse materials.

Download or read book Design of Functionalized Cyclic Aryl Ethers and Alkenes and Their Subsequent Ring opening Polymerization written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The ring-opening polymerization of a variety of cyclic and bicyclic monomers that were prepared via nucleophilic aromatic substitution reactions mediated by the cyclopentadienyliron moiety was explored. The ability to design structurally different monomers using this approach, allowed for the isolation of polymeric materials with different chemical and physical properties. It has been well established that organoiron complexes containing an assortment of functionalities can be prepared using this methodology. A variety of asymmetric cyclic aryl ethers were prepared following reaction of diiron complexes with a dinucleophile. Following cleavage of the metal moieties, the aromatic macrocycles were converted to the corresponding insoluble polyaromatic ethers via ring-opening polymerization in the presence of an anionic initiator. The ring-opening metathesis polymerization of a series of bicyclo[2.2.1]heptenes was also investigated. Two classes of polynorbornenes containing cationic iron moieties within their side chains were synthesized u ing organoiron chemistry, and subsequently polymerized in the presence of ruthenium-based catalyst. The resulting organometallic polynorbornenes, with terminal or lateral side chains displayed excellent solubility and thermal stability.

Download or read book The ring opening metathesis polymerisation of norbornene monomers containing amino acid ester funtionalities written by Matthew R. Giles and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Ring Opening Metathesis Polymerisation of Norbornene Monomers Containing Amino Acid written by and published by . This book was released on 1998 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis and Applications of Ring Opening Metathesis Polymerization Based Functional Block Copolymers written by Sanchita Biswas and published by . This book was released on 2010 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ring opening metathesis polymerization (ROMP) is established as one of the efficient controlled living polymerization methods which have various applications in polymer science and technology fields. The research presented in this dissertation addresses several applications of multifunctional well-defined norbornene-based block copolymers synthesized by ROMP using ruthenium-based Grubbs catalysts. These novel block copolymers were applied to stabilize maghemite nanoparticles, creating the superparamagnetic polymeric nanocomposites. The J-aggregation properties of the porphyrin dyes were improved via self-assembly with a customized norbornene polymer. Novel multimodal copolymer probes were synthesized for two-photon fluorescence integrin-targeted bioimaging. In Chapter 1 a brief overview of ROMP along with ruthenium metal catalysts and selected applications of the polymers related to this research is presented. Superparamagnetic maghemite nanoparticles are important in biotechnology fields, such as enhanced magnetic resonance imaging (MRI), magnetically controlled drug delivery, and biomimetics. However, cluster formation and eventual loss of nano-dimensions is a major obstacle for these materials. Chapter 2 presents a solution to this problem through nanoparticles stabiulized in a polymer matrix. The synthesis and chracterization of novel diblock copolymers, consisting of epoxy pendant anchoring groups to chelate maghemite nanoparticles and steric stabilizing groups, as well as generation of nanocomposites and their characterization, including surface morphologies and magnetic properties, is discussed in Chapter 2. In Chapter 3, further improvement of the nanocomposites by ligand modification and the synthesis of pyrazole-templated diblock copolymers and their impact to stabilize the maghemite nanocomposite are presented. Additionally, the organic soluble magnetic nanocomposites with high magnetizations were encapsulated in an amphiphilic copolymer and dispersed in water to assess their water stability by TEM. To gain a preliminary measure of biocopatibility of the micelle-encapsulated polymeric magnetic nanocomposites, cell-viability was determined. In Chapter 4, aggregation behaviors of two porphyrin-based dyes were investigated. A new amphiphilic homopolymer containing secondary amine moieties was synthesized and characterized. In low pH, the polymer became water soluble and initiated the stable J-aggregation of the porphyrin. Spectroscopic data supported the aggregation behavior. Two photon fluorescence microscopy (2PFM) has become a powerful technique in bioimaging for non-invasive imaging and potential diagnosis and treatment of a number of diseases via excitation in the near-infrared (NIR) region. The fluorescence emission upon two-photon absorption (2PA) is quadratically dependent with the intensity of excitation light (compared to the linear dependence in the case of one-photon absoprtion), offering several advantages for biological applications over the conventional one-photon absorption (1PA) due to the high 3D spatial resolution that is confined near the focal point along with less photodamage and interference from the biological tissues at longer wavelength (~700-900 nm). Hence, efficient 2PA absorbing fluorophores conjugated with specific targeting moieties provides an even better bioimaging probe to diagnose desired cellular processes or areas of interest The [alpha subscript v beta subscript 3] integrin adhesive protein plays a significant role in regulating angiogenesis and is over-expressed in uncontrolled neovascularization during tumor growth, invasion, and metastasis. Cyclic-RGD peptides are well-known antagonists of [alpha subscript v beta subscript 3] integrin which suppress the angiogenesis process, thus preventing tumor growth. In Chapter 5 the synthesis, photophysical studies and bioimaging is reported for a versatile norbornene-based block copolymer multifunctional scaffold containing biocompatible (PEG), two-photon fluorescent (fluorenyl), and targeting (cyclic RGD peptide) moieties. This water-soluble polymeric multi scaffold probe with negligible cytotoxicity exhibited much stronger fluorescence and high localization in U87MG cells (that overexpress integrin) compared to control MCF7 cells. The norbornene-based polymers and copolymers have quite remarkable versatility for the creation of advanced functional magnetic, photonic, and biophotonic materials.

Download or read book The Ring Opening Metathesis Polymerisation of Norbornene Monomers Containing Amino Acid ester Functionalities written by Matthew Robert Giles and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Olefin Metathesis in Supramolecular and Ring opening Polymerization written by Jedidiah M. Hastings and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: The need to develop dynamic materials that are capable of changing their properties in response to a changing environment has grown significantly over the past decade. As a result, new approaches to the synthesis of these "smart" materials are constantly being illuminated. Olefin metathesis has recently been elevated to the forefront of this area, as it has proven a reliable and versatile method for creating new carbon-carbon bonds. This allows for the incorporation of diverse functionality without a corresponding increase in synthetic difficulty or complexity. The work presented in this dissertation focuses on the creation of dynamic libraries of supramolecular polymers via olefin cross-metathesis. The polymers are synthesized from cytosine or easily prepared 2,4-diaminotriazines. Functional groups ranging from aromatic systems, alkanes, and amino-acids have been incorporated onto the backbones without altering the synthetic strategy. Binding constants have been found to be similar in strength to related compounds. In addition to the creation of supramolecular polymers, olefin metathesis has been used in this study to create designer polymers with a traditional, covalently bound backbone. These polymers have contained functionality ranging from chiral diols, which were shown to direct the stereochemistry of Grignard reactions, to nucleic acid bases, which can interact with their environment via Hydrogen bonding. Ring-opening metathesis polymerization was used to create the designer polymers from norbornene-derived bicyclic ring systems. The chiral diols were prepared from commercially available diethyl-L-tartrate. The nucleic acid bases were cytosine and adenine. Efforts have been started toward the incorporation of guanine and thymine.

Download or read book Synthesis of Side Chain Liquid Crystal Polymers by Living Ring Opening Metathesis Polymerization 2 Influence of Molecular Weight Polydispersity and Flexible Spacer Length n written by and published by . This book was released on 1992 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: The living ring opening metathesis polymerization of 5-carbo(n-(4'- METHOXY-4BIPHENYLYLoxyalkyl)bicylco2.2.1hept-2-ene (1-n, n=9-12) with Mo(CH-t- Bu)(NAr) (0-t-Bu)2 (Ar=2,6-C6H3-i-Pr2) is described. Polymers with degrees of polymerization from 5 to 100 and narrow molecular weight distributions (Mw/Mn=1. 07-1.28) were obtained in high yield. All polymers exhibit side chain crystallization along with a nematic mesophase. Isotropization temperatures increase with increasing molecular weight and then become independent of molecular weight at approximately 30-50 repeat units. Side chain crystallization is suppressed as molecular weight increases.

Download or read book Explorations Into the Synthesis and Reactivity of Polynorbornene Frameworks written by Victoria K. Kensy and published by . This book was released on 2019 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polynorbornenes are a highly versatile polymer that allows for much modification of the side chains and multiple methods for polymerization. Chapter 1 introduces our unique photoredox mediated ring-opening metathesis polymerization (photo-ROMP) technique for ring-opening metathesis polymerizations (ROMP) that utilizes an organic redox mediator and a vinyl ether initiator, in contrast to metal-based initiators traditionally used in ROMP. The reversibility of the redox-mediated initiation and propagation steps enable spatiotemporal control over the polymerization. In Chapter 2, we explore control over polynorbornene molecular weights using alpha olefins as chain transfer agents, allowing the initiator to be recycled to reduce costs and access low molecular weight oligomers. Molecular weights between 30 kDa and 1 kDa can be targeted simply through altering the stoichiometry of the reaction. Chapter 3 details our work on the development of a continuous flow reactor for large scale synthesis of photo-ROMP polymers. In Chapter 4, we report the discovery of a mechanochemical method to produce ROMP polynorbornene (ROMP-PNB) from vinyl-addition polynorbornene (VA-PNB). VA-PNBs with three different side chains were found to undergo ring-opening olefination upon sonication in dilute solutions. The sonicated polymers exhibited spectroscopic signatures consistent with conversion of the bicyclic norbornane repeat units into ROMP-PNB. In Chapter 5, we investigated the reversible hetero-Diels-Alder reaction of 1,2-oxazines derived from a peralkylcyclopentadiene and a series of nitrosocarbonyl dienophiles. The nature of the dienophile was found to impart broad tunability to the dynamic character of the oxazine adducts. The reversibility was also observed in polymeric systems of a ROMP-PNB framework. The fidelity of the reaction and tunable sensitivity toward elevated temperature and water signify potential applications in the development of dynamic covalent materials or delivery systems for small molecule payloads.

Download or read book Synthesis and Characterization of Ring opening Metathesis Polymers with Pendant Carborane Groups written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: By Alice Man.

Download or read book Synthesis and Characterization of Functionalized Norbornene Monomers and Their Resulting Ring opening Metathesis Polymers and Copolymers written by Joshua David Biberdorf and published by . This book was released on 2011 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: The work reported herein describes efforts to create ring-opening metathesis block copolymers and homopolymers. The block copolymers were studied to gain insight into the local nanoscale environment of a block copolymer thin film. Additionally, perylene containing homopolymers were characterized in light of their possible use as an n-type material. In the first section of the thesis, the synthesis of diblock copolymers consisting of two blocks with very different dynamics is described. The covalent attachment of a molecular rotor which is sensitive to its local environment allowed the study of the dynamics of the polymers in thin films. The emissive intensity as a function of temperature allowed us to see discontinuity in the rates of change, indicating a change in the local environment corresponding to the transition of the polymer from a glassy to rubbery state. The corresponding temperature, to this event, is known as the glass transition temperature, Tg. Additionally, a polymer featuring a covalently bound n-type molecule, perylene diimide, was synthesized. The photophysical properties, including aggregation in dilute solution, are described. The material is expected to demonstrate the ability to efficiently transport negative charge, acting as n-type material in organic electronics.