Side-Chain Hydrogen-Bonded Polymers

Another aspect of side-chain hydrogen-bonded polymers is related to the miscibility enhancement between immiscible polymers via (weak) hydrogenbonding interaction, generating polymer blends. This topic was described in Sect. 3.1, the interested reader is referred to this section within this review. 

Nilsson et al. designed an experiment to test the ability of a polymer to directly detect conformational changes within peptide/protein structure [27]. Using the zwitterionic polythiophene derivative, POWT, they succeeded in detecting the distinct conformations of synthetic peptides. The mechanism was concluded to be based on the polymer side chains charged interactions and hydrogen bonding with the proteins. 

Fig. 21 Assembly of polymers via triple-hydrogen bonds, a Formula of the flavine/2,6-diamino-triazine and thymine/2,6-diaminotriazine interactions, b Formation of nanopar-ticles/polymer aggregates, c Polymersome formation by aggregation of poly(norbornenes) and poly(styrenes) bearing N-bisacyl-2,6-diamino-pyridine and thymine side-chains, respectively. Reprinted with permission from [104,105]...

Another type of supramolecular side-chain polymers (shown in Fig. lOB) is obtained by the complexation of functionalized mesogenic molecules with polymer backbones. The hydrogen-bonded complex of 37 is obtained by mixing poly(4-vinylpyridine) or poly(4-vinylpyridine-co-styrene) with mesogenic compounds terminated by a carboxylic acid moiety through a flexible spacer [84-88]. The hydrogen bonding between imidazole and carboxylic acid is also useful for the formation of supramolecular complexes. Polymeric complex 38 exhibits a smectic A phase from 10 to 65 °C [89]. 

Binder W, Zirbs R (2007) Supramolecular polymers and networkswith hydrogen bonds in the main- and side-chain. In Binder W (ed) Hydrogen bonded polymers, vol 207. Springer, Berlin, pp 1-78... 

Scheme 8. Generation of nonsymmetrical liquid crystalline dimers, twin dimers and side chain liquid crystalline polymers by specific hydrogen bonding interactions.

Schematic illustration of the structure of a typical side-chain LC polymer is shown in Scheme I. Mesogenic units are covalently attached to the polymer backbone via a flexible spacer.Our aim in the present study is to construct new type of side-chain liquid crystalline polymers through intermolecular hydrogen bonding in place of covalent bonding. Hydrogen bonding may be used to connect the part where the broken line shows in Sceme I. We describe self-assembly of LC polymers through selective recognition between a polymer side chain and low-molecular-weight molecules.

Various hydrogen-bond ring sizes were tested with 5-, 6- and 7-membered hydrogen-bonded polymer ligands that are derived from poly(methylmeth-acrylate). The poly[3-(2,2,2-triphenylacetylamino)propionate], poly[(Val-0")-MA], ligand with a weak intramolecular 5-membered hydrogen bond in the polymer side chain produces a calcite. 

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