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Periodically grafted Amphiphilic Copolymers: Nonionic analogues of Ionenes

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dc.contributor.author Roy, R K
dc.contributor.author Bhoje Gowd, E
dc.contributor.author Ramakrishnan, S
dc.date.accessioned 2013-05-22T05:58:35Z
dc.date.available 2013-05-22T05:58:35Z
dc.date.issued 2012
dc.identifier.citation Macromolecules 45:3063-3069;2012 en_US
dc.identifier.uri http://hdl.handle.net/123456789/361
dc.description.abstract We describe a novel class of periodically grafted amphiphilic copolymers (PGACs) that could serve as nonionic functional mimics of ionenes, the primary difference being that the periodically occurring charged units along the backbone of ionenes are replaced by hydrophilic oligoethylene glycol segments. The synthesis and properties of this new class of segmented polymers that carry a hydrophobic alkylene polyester backone with periodically placed hydrophilic oligo(oxyethylene) pendant units are presented. When the length of the intervening alkylene segment is adequately long, 22-carbons in this case, and the pendant unit is a hexaethylene glycol monomethyl ether (HEG) segment, the polymer chain appears to adopt a folded zigzag conformation, reminiscent of the accordion-type structure formed by cationic ionenes. This transformation is driven by the intrinsic immiscibility of the alkylene and HEG segments and is reinforced by the strong tendency for long chain alkylene segments to crystallize in a paraffinic lattice. Evidence of the formation of such structures comes from the AFM images, which reveal the formation of remarkably flat pancake-like aggregates that are formed by the lateral aggregation of individually collapsed polymer chains; importantly, the heights of these structures match well with the lamellar layer-spacing obtained from SAXS studies of bulk samples. DSC studies further confirm the crystallization of the intervening alkylene segments, especially when they are long (C22), suggesting the formation of the folded zigzag structures. In a suitably designed PGAC that carries diacetylene units symmetrically placed within the alkylene segment, attempts were made to cross-polymerize the diacetylene units and generate PEGylated nanoparticles. However, these attempts were unsuccessful demonstrating the very stringent geometric requirements for the topotactic polymerization of diacetylenes. en_US
dc.language.iso en en_US
dc.publisher American Chemical Society, USA en_US
dc.subject Amphiphilic copolymers en_US
dc.title Periodically grafted Amphiphilic Copolymers: Nonionic analogues of Ionenes en_US
dc.type Article en_US


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