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Supramolecular Polymers (supramolecular + polymer)
Selected AbstractsElectrically Conductive Hydrogen-Bond-Based Supramolecular Polymer with a Tetrathiafulvalene Moiety: Modulation of Electrical Conductivity and Flexibility of Film by External StimulusCHEMISTRY - AN ASIAN JOURNAL, Issue 10 2010Seong Jib Choi Best supporting role in a film! The 2-deoxyguanosine derivatives having tetrathiafulvalene moieties for a construction of stimuli-responsive supramolecular polymer have been prepared. Owing to a hydrogen-bonding network, the self-supporting film can be fabricated by a simple procedure. The electrical conductivity and flexibility of the film can be modulated by oxidants. The film with TCNQ exhibits electrical conductivity of 3.7×10,2,S,cm,1. [source] Metal Coordination Mediated Reversible Conversion between Linear and Cross-Linked Supramolecular Polymers,ANGEWANDTE CHEMIE, Issue 6 2010Feng Wang Dr. Dynamisches Duo: Dynamische supramolekulare Polymere mit unterschiedlichen Topologien, z.,B. lineare und vernetzte Strukturen (siehe Schema), können reversibel ineinander umgewandelt werden. Als externe Auslöser dienen nichtkovalente Wirt-Gast- und Metall-Ligand-Erkennungsmotive. [source] Supramolecular Polymers and Chromonic Mesophases Self-Organized from Phosphorescent Cationic Organoplatinum(II) Complexes in Water,ANGEWANDTE CHEMIE, Issue 41 2009Wei Lu Dr. Weiche Materie mit hartem Kern: Durch PtII,,,PtII - und hydrophobe Wechselwirkungen gehen planare Organoplatin(II)-Kationen mit Chlorid- oder Sulfat-Gegenionen in Wasser in rot emittierende, viskoelastische, gestapelte Mesophasen über, aus denen leicht ausgerichtete Filme und uniaxiale Mikrofasern mit cofacialer Molekülanordnung erhalten werden. [source] Dynamic Supramolecular Polymers Based on Benzene-1,3,5-tricarboxamides: The Influence of Amide Connectivity on Aggregate Stability and Amplification of ChiralityCHEMISTRY - A EUROPEAN JOURNAL, Issue 3 2010Patrick Abstract N-Centred benzene-1,3,5-tricarboxamides (N-BTAs) composed of chiral and achiral alkyl substituents were synthesised and their solid-state behaviour and self-assembly in dilute alkane solutions were investigated. A combination of differential scanning calorimetry (DSC), polarisation optical microscopy (POM) and X-ray diffraction revealed that the chiral N-BTA derivatives with branched 3,7-dimethyloctanoyl chains were liquid crystalline and the mesophase was assigned as Colho. In contrast, N-BTA derivatives with linear tetradecanoyl or octanoyl chains lacked a mesophase and were obtained as crystalline compounds. Variable-temperature infrared spectroscopy showed the presence of threefold, intermolecular hydrogen bonding between neighbouring molecules in the mesophase of the chiral N-BTAs. In the crystalline state at room temperature a more complicated packing between the molecules was observed. Ultraviolet and circular dichroism spectroscopy on dilute solutions of N-BTAs revealed a cooperative self-assembly behaviour of the N-BTA molecules into supramolecular polymers with preferred helicity when chiral alkyl chains were present. Both the sergeants-and-soldiers as well as the majority-rules principles were operative in stacks of N-BTAs. In fact, the self-assembly of N-BTAs resembles closely that of their carbonyl (CO)-centred counterparts, with the exception that aggregation is weaker and amplification of chirality is less pronounced. The differences in the self-assembly of N- and CO-BTAs were analysed by density functional theory (DFT) calculations. These reveal a substantially lower interaction energy between the monomeric units in the supramolecular polymers of N-BTAs. The lower interaction energy is due to the higher energy penalty for rotation around the PhNH bond compared to the PhCO bond and the diminished magnitude of dipole,dipole interactions. Finally, we observed that mixed stacks are formed in dilute solution when mixing N-BTAs and CO BTAs. [source] Supramolecular polymers formed by cinnamoyl cyclodextrinsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2003Akira Harada Abstract 6-Cinnamoyl ,-cyclodextrin (6-CiO-,-CD) and 6-cinnamoyl ,-cyclodextrin (6-CiO-,-CD) were prepared. 6-CiO-,-CD formed intermolecular complexes to give supramolecular oligomers. 6-CiO-,-CD formed insoluble supramolecular complexes in the solid state. The structures of these complexes are discussed. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3519,3523, 2003 [source] Supramolecular polymers: from scientific curiosity to technological realityMACROMOLECULAR SYMPOSIA, Issue 1 2003A.W. Bosnian Abstract Supramolecular polymers[1] are introduced as a new approach to come to materials in which the repeating units are not connected by covalent bonds but by specific secondary interactions. Self-complementary quadruple hydrogen bonded structures with high association constants are presented as easy to synthesize fragments in supramolecular polymers. Some of the many possibilities of equilibrium polymers are discussed, while it is shown that these supramolecular polymers can obtain materials properties normally only obtained with macromolecules. [source] Thermal stability of some self-assembling hydrogen-bonded polymers and related model complexes,POLYMER INTERNATIONAL, Issue 11 2002Gordon Armstrong Abstract The thermal stability of polymers is of fundamental importance both in processing and in many applications, eg, injection moulding, hot melts. As part of an investigation to determine the suitability of supramolecular polymers for novel applications in materials science, the thermal behaviour of two model compounds representing the principal classes of supramolecular polymer has been studied in some detail. p -Methoxybenzoic acid was complexed with 1,2-di(4-pyridyl)ethylene in 2:1 ratio as a model compound representing liquid,crystal association chain supramolecular polymers. It is proposed that the model compound degrades as a single species obeying first-order kinetics; the activation energy (Eact) of the degradation process was calculated to be 127,kJ,mol,1. A model ureidopyrimidinone dimer degraded in two steps, also following first order kinetics, with Eact,=,71.5,kJ,mol,1. The dimer was unaffected by annealing, suggesting that related polymers may be used at elevated temperatures. Polymer analogues of both model compounds were synthesized and their thermal behaviour was found to parallel that of the models. In light of these results, the implications for processing both supramolecular polymers are also considered. © 2002 Society of Chemical Industry [source] Electrically Conductive Hydrogen-Bond-Based Supramolecular Polymer with a Tetrathiafulvalene Moiety: Modulation of Electrical Conductivity and Flexibility of Film by External StimulusCHEMISTRY - AN ASIAN JOURNAL, Issue 10 2010Seong Jib Choi Best supporting role in a film! The 2-deoxyguanosine derivatives having tetrathiafulvalene moieties for a construction of stimuli-responsive supramolecular polymer have been prepared. Owing to a hydrogen-bonding network, the self-supporting film can be fabricated by a simple procedure. The electrical conductivity and flexibility of the film can be modulated by oxidants. The film with TCNQ exhibits electrical conductivity of 3.7×10,2,S,cm,1. [source] Side-chain supramolecular polymers with induced supramolecular chirality through H-bonding interactionsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2008Francisco Vera Abstract Side-chain supramolecular polymers that show columnar mesomorphism have been prepared through H-bonding interactions between a polyvinylpyridine polymer as H-acceptor and different H-donors derived from benzoic acid. These compounds have been designed according to a promesogenic structure, that is, either disk-like or banana-like, to promote stacking and therefore the formation of columnar arrangements. IR studies confirmed the formation of H-bonds and demonstrated that the H-bond intensity decreases upon increasing temperature. The mesophase organizations were studied by polarized optical microscopy, differential scanning calorimetry, and X-ray diffraction. Associations containing poly-3-methyl-4-vinylpyridine showed supramolecular optical activity, as evidenced by circular dichroism studies on thin films. It is proposed that these supramolecular polymers adopt a helical structure that can be biased toward a given handedness by virtue of the configuration of the stereogenic centers in the peripheral tails of the acids. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5528,5541, 2008 [source] Self-assembly of supramolecular polymers into tunable helical structuresJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 6 2008Ho-Joong Kim Abstract There is growing interest in the design of synthetic molecules that are able to self-assemble into a polymeric chain with compact helical conformations, which is analogous to the folded state of natural proteins. Herein, we highlight supramolecular approach to the formation of helical architectures and their conformational changes driven by external stimuli. Helical organization in synthetic self-assembling systems can be achieved by the various types of noncovalent interactions, which include hydrogen bonding, solvophobic effects, and metal-ligand interactions. Since the external environment can have a large influence on the strength and configuration of noncovalent interactions between the individual components, stimulus-induced alterations in the intramolecular noncovalent interactions can result in dynamic conformational change of the supramolecular helical structure thus, driving significant changes in the properties of the materials. Therefore, these supramolecular helices hold great promise as stimuli-responsive materials. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1925,1935, 2008 [source] Effect of stoichiometry on liquid crystalline supramolecular polymers formed with complementary nucleobase pair interactionsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 17 2006Kelly A. Burke Abstract We report herein studies on the liquid crystalline behavior of a series of supramolecular materials that contain different ratios of two complementary symmetrically-substituted alkoxy-bis(phenylethynyl)benzene AA- and BB-type monomers. One monomer has thymine units placed at either end of the rigid mesogenic core, while the other has N6 -(4-methoxybenzoyl)-adenine units placed on the ends. Differential scanning calorimetric and polarized optical microscopy studies have been carried out on these systems. These studies show that the material's behavior is strongly dependent on its thermal history. As a result, the materials can exhibit, on heating, either a liquid crystalline phase, a crystalline phase, or the coexistence of crystalline and liquid crystalline regions. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5049,5059, 2006 [source] Supramolecular polymers: from scientific curiosity to technological realityMACROMOLECULAR SYMPOSIA, Issue 1 2003A.W. Bosnian Abstract Supramolecular polymers[1] are introduced as a new approach to come to materials in which the repeating units are not connected by covalent bonds but by specific secondary interactions. Self-complementary quadruple hydrogen bonded structures with high association constants are presented as easy to synthesize fragments in supramolecular polymers. Some of the many possibilities of equilibrium polymers are discussed, while it is shown that these supramolecular polymers can obtain materials properties normally only obtained with macromolecules. [source] Biodegradable polymers applied in tissue engineering research: a reviewPOLYMER INTERNATIONAL, Issue 2 2007Monique Martina Abstract Typical applications and research areas of polymeric biomaterials include tissue replacement, tissue augmentation, tissue support, and drug delivery. In many cases the body needs only the temporary presence of a device/biomaterial, in which instance biodegradable and certain partially biodegradable polymeric materials are better alternatives than biostable ones. Recent treatment concepts based on scaffold-based tissue engineering principles differ from standard tissue replacement and drug therapies as the engineered tissue aims not only to repair but also regenerate the target tissue. Cells have been cultured outside the body for many years; however, it has only recently become possible for scientists and engineers to grow complex three-dimensional tissue grafts to meet clinical needs. New generations of scaffolds based on synthetic and natural polymers are being developed and evaluated at a rapid pace, aimed at mimicking the structural characteristics of natural extracellular matrix. This review focuses on scaffolds made of more recently developed synthetic polymers for tissue engineering applications. Currently, the design and fabrication of biodegradable synthetic scaffolds is driven by four material categories: (i) common clinically established polymers, including polyglycolide, polylactides, polycaprolactone; (ii) novel di- and tri-block polymers; (iii) newly synthesized or studied polymeric biomaterials, such as polyorthoester, polyanhydrides, polyhydroxyalkanoate, polypyrroles, poly(ether ester amide)s, elastic shape-memory polymers; and (iv) biomimetic materials, supramolecular polymers formed by self-assembly, and matrices presenting distinctive or a variety of biochemical cues. This paper aims to review the latest developments from a scaffold material perspective, mainly pertaining to categories (ii) and (iii) listed above. Copyright © 2006 Society of Chemical Industry [source] Thermal stability of some self-assembling hydrogen-bonded polymers and related model complexes,POLYMER INTERNATIONAL, Issue 11 2002Gordon Armstrong Abstract The thermal stability of polymers is of fundamental importance both in processing and in many applications, eg, injection moulding, hot melts. As part of an investigation to determine the suitability of supramolecular polymers for novel applications in materials science, the thermal behaviour of two model compounds representing the principal classes of supramolecular polymer has been studied in some detail. p -Methoxybenzoic acid was complexed with 1,2-di(4-pyridyl)ethylene in 2:1 ratio as a model compound representing liquid,crystal association chain supramolecular polymers. It is proposed that the model compound degrades as a single species obeying first-order kinetics; the activation energy (Eact) of the degradation process was calculated to be 127,kJ,mol,1. A model ureidopyrimidinone dimer degraded in two steps, also following first order kinetics, with Eact,=,71.5,kJ,mol,1. The dimer was unaffected by annealing, suggesting that related polymers may be used at elevated temperatures. Polymer analogues of both model compounds were synthesized and their thermal behaviour was found to parallel that of the models. In light of these results, the implications for processing both supramolecular polymers are also considered. © 2002 Society of Chemical Industry [source] Recent work on entropically-driven ring-opening polymerizations: some potential applications,POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 2-3 2005Philip Hodge Abstract The entropically-driven ring-opening polymerization of macrocyclic monomers (>ca. 14 ring atoms per repeat unit) and/or macrocyclic oligomers is a relatively new method of polymer synthesis that exploits the well-known phenomenon of ring-chain equilibria. It attracts interest because of its novel features. For example, these ring-opening polymerizations emit no volatiles and little or no heat. This review considers the principles of entropically-driven ring-opening polymerizations, gives selected examples and discusses potential applications. The latter include micromolding, high throughput syntheses and the synthesis of supramolecular polymers. Copyright © 2005 John Wiley & Sons, Ltd. [source] Dynamic Supramolecular Polymers Based on Benzene-1,3,5-tricarboxamides: The Influence of Amide Connectivity on Aggregate Stability and Amplification of ChiralityCHEMISTRY - A EUROPEAN JOURNAL, Issue 3 2010Patrick Abstract N-Centred benzene-1,3,5-tricarboxamides (N-BTAs) composed of chiral and achiral alkyl substituents were synthesised and their solid-state behaviour and self-assembly in dilute alkane solutions were investigated. A combination of differential scanning calorimetry (DSC), polarisation optical microscopy (POM) and X-ray diffraction revealed that the chiral N-BTA derivatives with branched 3,7-dimethyloctanoyl chains were liquid crystalline and the mesophase was assigned as Colho. In contrast, N-BTA derivatives with linear tetradecanoyl or octanoyl chains lacked a mesophase and were obtained as crystalline compounds. Variable-temperature infrared spectroscopy showed the presence of threefold, intermolecular hydrogen bonding between neighbouring molecules in the mesophase of the chiral N-BTAs. In the crystalline state at room temperature a more complicated packing between the molecules was observed. Ultraviolet and circular dichroism spectroscopy on dilute solutions of N-BTAs revealed a cooperative self-assembly behaviour of the N-BTA molecules into supramolecular polymers with preferred helicity when chiral alkyl chains were present. Both the sergeants-and-soldiers as well as the majority-rules principles were operative in stacks of N-BTAs. In fact, the self-assembly of N-BTAs resembles closely that of their carbonyl (CO)-centred counterparts, with the exception that aggregation is weaker and amplification of chirality is less pronounced. The differences in the self-assembly of N- and CO-BTAs were analysed by density functional theory (DFT) calculations. These reveal a substantially lower interaction energy between the monomeric units in the supramolecular polymers of N-BTAs. The lower interaction energy is due to the higher energy penalty for rotation around the PhNH bond compared to the PhCO bond and the diminished magnitude of dipole,dipole interactions. Finally, we observed that mixed stacks are formed in dilute solution when mixing N-BTAs and CO BTAs. [source] Photoresponsive Self-Assembly and Self-Organization of Hydrogen-Bonded Supramolecular TapesCHEMISTRY - A EUROPEAN JOURNAL, Issue 15 2006Shiki Yagai Dr. Abstract Self-assembling building blocks that are readily functionalizable and capable of achieving programmed hierarchical organization have enabled us to create various functional nanomaterials. We have previously demonstrated that N,N, -disubstituted 4,6-diaminopyrimidin-2(1,H)-one (DAP), a guanine,cytosine hybridized molecule, is a versatile building block for the creation of tapelike supramolecular polymer species in solution. In the current study, DAP was functionalized with azobenzene side chains. 1H NMR, UV/Vis, and dynamic light scattering studies confirmed the presence of nanometer-scale tapelike supramolecular polymers in alkane solvents at micromolar regimes. At higher concentrations (millimolar regimes), the supramolecular polymers hierarchically organized into lamellar superstructures to form organogels, as shown by X-ray diffraction and polarized optical microscopy. Remarkably, the azobenzene side chains are photoisomerizable even in the supramolecular polymers, owing to their loosely packed state supported by the rigid hydrogen-bonded scaffold, enabling us to establish photocontrollable supramolecular polymerization and higher order organization of the tapelike supramolecular polymers into lamellar superstructures. [source] | |||||||||||||