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Supramolecular Polymers

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*4/27/2012

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 2. Supramolecular chemistry refers to the area of chemistry beyond the molecules and focuses on the chemical systems made up of a discrete number of assembled molecular subunits or components. The forces responsible for the spatial organization may vary from weak (intermolecular forces, electrostatic or hydrogen bonding) to strong (covalent bonding), provided that the degree of electronic coupling between the molecular component remains small with respect to relevant energy parameters of the component.  Traditional chemistry focuses on the covalent bond, supramolecular chemistry examines the weaker and reversible noncovalent interactions between molecules. These forces include hydrogen bonding, metal coordination, hydrophobic forces, van der Waals forces, pi-pi interactions and electrostatic effects. Important concepts that have been demonstrated by supramolecular chemistry include molecular self-assembly, folding, molecular recognition, host-guest chemistry, mechanically-interlocked molecular architectures, and dynamic covalent chemistry.  The study of non-covalent interactions is crucial to understanding many biological processes from cell structure to vision that rely on these forces for structure and function. Biological systems are often the inspiration for supramolecular research.”    (Wikipedia, Supramolecular Chemistry, 8/17/2011)

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1. “Supramolecular structures are created from organic compounds which are formed from the non-covalent bonding of monomer, oligomer or polymeric core modules as building blocks. The most important feature of supramolecular chemistry is that the building blocks are reversibly held together by intermolecular forces--non-covalent self-assembly. The bond formation between atoms in molecular chemistry is based on covalent assembly, which is kinetically or thermodynamically controlled. This non-covalent synthesis enables the building up of supramolecular entities having architectures and features that are sometimes extremely difficult to prepare by covalent synthesis.”

“The use of self-complimentary hydrogen bonding in a supramolecular structure is an example of a strong, in terms of bond strength, non-covalent association where hydrogen bonds are the only force keeping the core modules together. These structures exist under thermodynamic equilibrium so can be used to generate supramolecular polymers which respond to a change in external stimuli (e.g. temperature or solvent). The use of quadruple hydrogen bonds has been demonstrated to increase both the strength and specificity of hydrogen bonding interactions. Supramolecular materials are required to exhibit a broad range of properties because of their many industrial applications, for example, in thermoplastic elastomers, cosmetics and superglues.”

“The physical properties of supramolecular materials (e.g. glass transition temperature, melting point, viscosity) can be tailored according to the polymer, the core modules used, the synthesis method and the type of hydrogen bonding array used. Also, synthesis of core modules capable of forming strong hydrogen bonds is particularly desirable. The synthesis of supramolecular polymers based on the self-assembly of DDAA modules (Donor and Acceptor) has previously been reported in WO 98/14504 as being mainly restricted to the ureidopyrimidinones (UPy). UPy modules have been chemically incorporated within polymers to produce supramolecular materials with improved processing properties in melt or solution whilst maintaining physical properties in the solid state.”

[Bala et al, US Patent 8,076,436 (12/13/2011)]

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Roger D. Corneliussen
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Copyright 2012 by Roger D. Corneliussen.
No part of this transmission is to be duplicated in any manner or forwarded by electronic mail without the express written permission of Roger D. Corneliussen
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* Date of latest addition; date of first entry is 8/17/2011.