The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details.
Deposited in DRO:PW tnury PHIS Version of attached le: ulished ersion Peer-review status of attached le: eerEreviewed Citation for published item: unpilD wF nd skklD yF nd orkkeliD wF nd tokelD uF nd erimD F nd holnyD sFF nd frsD F nd ten frinkeD qF nd rorsurghD vFiF nd ¦ lssonD vFEyF nd wonkmnD eFF @PHHPA 9olrized luminesene from selfEssemledD lignedD nd leved suprmoleules of highly ordered rodlike polymersF9D epplied physis lettersFD VI @VAF ppF IRVWEIRWIF Further information on publisher's website: httpsXGGdoiForgGIHFIHTQGIFIRWWPPP Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. A hierarchical self-assembly in comb-shaped supramolecules of conjugated rodlike polymers is reported. The supramolecules consist of poly͑2,5-pyridinediyl͒, acid dopants, and hydrogen bonded alkyl side chains. A thermotropic smectic state with an exceptionally large coherence length is formed without additional solvent. This allows facile overall alignment resulting in high dichroism and polarized photoluminescence. Solid films are formed by cleaving side groups from the supramolecules which retain the optical anisotropy together with the high photoluminescence quantum yield of pristine polymer.
The efficient operation of polymer light-emitting diodes (LEDs) requires balanced injection and transport of electrons and holes. This has stimulated much research into suitable electron-injecting and transporting materials. We report the use of polypyridine as an efficient electron-transporting polymer. We have achieved much-improved LED performance by incorporating polypyridine as an electron-transporting layer in a poly(p-phenylene vinylene) (PPV) LED and optimizing layer thicknesses to balance transport of electrons and holes. The external quantum efficiency of these LEDs is 0.25%, 60 times greater than similar devices without the electron-transporting layer.
The process of self-organization [1] facilitates formation of ordered polymeric nanoscale structures, [2±7] and hierarchical (tandem) self-organization [8±10] further allows elaboration of responsive materials based on sequences of order-order and order-disorder transitions. [8] Application to rod-like polymers (such as p-conjugated electroactive polymers) could lead to possible new applications, but is not straightforward because such polymers tend to be infusible and poorly soluble. For polymers containing rod-like moieties, self-organization has been achieved based on di-block copolymers with flexible blocks, [11,12] comb-block copolymers with flexible side chains (so-called ªhairy rodsº), [13±15] and sufficiently dilute mixtures with strong amphiphilic acids. [16,17] Here we show that one of the simplest p-conjugated electroactive rod-like polymers poly(2,5-pyridine diyl) (PPY), i.e. polypyridine or poly(p-pyridine), stoichiometrically protonated by the simplest sulfonic acid, i.e., methane sulfonic acid (MSA), to form a polymeric salt poly(2,5-pyridine diyl) methane sulfonate, PPY(MSA) 1.0 , forms self-organized nanoscale structures upon complexing with selected alkylphenols, such as octyl gallate (octyl 3,4,5-trihydroxybenzoate, OG). In this case, the strength of the hydrogen bonding was sufficient to compensate for the repulsion due to the alkyl tails, which is necessary for self-organization. A supramolecular structure was formed which resembled ªhairy rodº polymers with a fascinating phase behavior. For example, at high temperatures, the mixture consisting of PPY (MSA) 1.0 and OG in the molar ratio 1.0:2.0, formed a homogeneous solution at the resolution of optical microscopes. Cooling below the order-disorder transition (T ODT » 180 C) the mixture became a self-organized complex fluid. At still lower temperatures (T < 110 C), cocrystallization within the polar layers, consisting of protonated PPY-chains, methylsulfonate counter ions, and the aromatic part of OG, was observed. Such supramolecular ªhairy rodº complexes open a straightforward route to prepare processible (fusible) block copolymer-like ordered structures in a number of rod-like polymers. Polymers containing main chain pyridine groups have aroused considerable interest in relation to photonic applications.
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