Main-Chain Manipulation

Main-chain manipulation offers an opportunity to dramatically change the electronic and physical properties of the PAEs. Popular approaches are the introduction of meta linkages into the polymers, the introduction of aromatic hydrocarbons other than benzene, the introduction of heterocycles, and the substitution of a fraction of the connecting alkyne groups by double bonds. The last strategy leads to polymers that are hybrids between PPEs and PPVs. 

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Abstract. This article reviews mainly the results of our recent research on the relationship between the structure and the luminescence properties of PPV derivatives. PPV derivatives are particularly useful in an effort toward the establishment of such relationship because their chemical structures can be manipulated very systematically. Attachment of a wide variety of substituents, inclusion of kinky structural units, modification of main chain structures by inclusion of hole- and/or electron-transferring structures, and blending of polymers having different optical and electronic properties are representative approaches. The device characteristics of the light-emitting diodes (LEDs) fabricated from these polymers are discussed in relation to their structures. In certain cases, their photoluminescence (PL) properties are compared with their electroluminescence (EL) properties. 

The rod-coil approach as a means to manipulate supramolecular structure as a function of rod volume fraction was reported to be extended to main chain multiblock copolymer systems, which generate bicontinuous cubic and hexagonal columnar mesophases depending on the rod-to-coil volume fraction [95,96]. For example, rod-coil multiblock copolymer (28) based on short length of coil (rod volume fraction, /ro(j = 0.38) exhibits a bicontinuous cubic mesophase, while copolymer (29) based on higher coil volume fraction (/i-od = 0.29) shows a hexagonal columnar mesophase. A notable feature... 

Abequose residues in S. typhimurium occur as branches of O side-chain, and are not found in its main chain (see Fig. 1). Indeed, the enzymic polymerization readily occurs in the absence of CDP-abequose, hence, it was thought possible that abequose residues are added after the synthesis of the main chain of O side-chain polysaccharide is completed. However, this hypothesis appears unlikely in view of the following results. (I) Under certain experimental conditions, the incorporation of D-mannose, L-rhamnose, and D-galactose is strongly stimulated by the simultaneous presence of CDP-abe-quose. (2) By skilful manipulation of the conditions of reaction. 

A rich domain emerges from the combination of polymer chemistry with supramolecular chemistry, defining a supramolecular polymer chemistry [23, 24]. It involves the designed manipulation of molecular interactions (hydrogen bonding, donor-acceptor effects, etc.) and recognition processes to generate main-chain (or side-chain)... 

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