Functionalized Poly(3-hexylthiophene)s via Lithium–Bromine Exchange

Poly(3-hexylthiophene) (P3HT) is one of the most extensively investigated conjugated polymers and has been employed as the active material in many devices including field-effect transistors, organic photovoltaics and sensors. As a result, methods to further tune the properties of P3HT are desirable for specific applications. Herein, we report a facile postpolymerization modification strategy to functionalize the 4-position of commercially available P3HT in two simple steps–bromination of the 4-position of P3HT (Br–P3HT) followed by lithium−bromine exchange and quenching with an electrophile. We achieved near quantitative lithium–bromine exchange with Br–P3HT, which requires over 100 thienyl lithiates to be present on a single polymer chain. The lithiated-P3HT is readily combined with functional electrophiles, resulting in P3HT derivatives with ketones, secondary alcohols, trimethylsilyl (TMS) group, fluorine, or an azide at the 4-position. We demonstrated that the azide-modified P3HT could undergo Cu-catalyzed or Cu-free click chemistry, significantly expanding the complexity of the structures that can be appended to P3HT using this method.National Science Foundation (U.S.) (ECCS-0939514

Synthesis and Characterization of Polythiophenes Bearing Aromatic Groups at the 3-Position

Regioregular poly(3-(4'-(3 '',7 ''-dimethyloctoxy)phenyl)thiophene) (P3PhT) and poly(3-(4'-(3 '',7 ''-dimethyloctoxy)-3'-pyridinyl)thiophene) (P3PyT) were successfully prepared with reasonably high molecular weights and low polydispersity indices by the Grignard metathesis (GRIM) polymerization. These polymers were found to be thermally stable up to 360-390 degrees C, depending on the phenyl or pyridinyl linker in the bristle. Both polymer films revealed a molecularly multilayer structure (i.e., lamellar structure) whose layers stacked normal to the film plane; each lamella consists of two sublayers, namely ordered and amorphous layers. The amorphous sublayer was composed of a bilayer formed from the bristles. The ordered sublayer in P3PhT consisted of laterally stacked 3-phenylthiophene backbone chains, whereas that of P3PyT consisted of thiophene backbone chains without the pyridinyl linker. These ordered sublayer formations led a longer pi-conjugation length. The enhanced pi-conjugation lengths were reflected in their optical and electronic properties, showing that both P3PhT and P3PyT exhibited a lower highest occupied molecular orbital (HOMO) level and lower energy band gap compared to those of poly(3-hexylthiophene) (P3HT). Overall, the structure and properties of P3PhT and P3PyT make them promising materials for advanced polymer solar cells having an excellent performance.X111720sciescopu

Study on Thin film Morphology of Lamellar-forming Diblock Copolythiophene

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Synthesis and characterization of block copolythiophene with hexyl and triethylene glycol side chains

A well-defined diblock copolythiophene, poly(3-hexylthiophene)-b-poly(3-(2-(2-(2-methoxyethoxy) ethoxy)ethoxy)methylthiophene) (P3HT-b-P3TEGT) was successfully synthesized by a Grignard metathesis (GRIM) polymerization. The structure of the block copolymer was confirmed by size exclusion chromatography (SEC), H-1 NMR spectroscopy, differential scanning calorimetry (DSC), ultraviolet-visible (UV-vis) spectroscopy and fluorescence spectroscopy. The self-assembled structure of the block copolythiophene was investigated by atomic force microscopy (AFM), transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS), and synchrotron grazing incidence X-ray scattering (GIXS). These analyses found that the block components in films form vertically oriented lamellar structure via phase separation. Furthermore, both the phases were found to consist of molecular multi-layers respectively, in which the layers stack in the out-of-plane of the film. The P3HT phase exhibited crystalline, which is originated from the pi-pi stacked thiophene backbones. In contrast, the poly(3-(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)methylthiophene) (P3TEGT) phase revealed amorphous. Overall, the amphiphilic nature of P3HT-b-P3TEGT successfully demonstrated to lead to well-defined self-assembly structure in films. (C) 2011 Elsevier Ltd. All rights reserved.X112728sciescopu

Synthesis and Characterization of Polythiophene including Phenyl & Pyridinyl Groups at the 3-Position

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Synthesis and Transfer of Chirality in Supramolecular Hydrogen Bonded Conjugated Diblock Copolymers

The synthesis of a block copoly­(3-alkylthiophene) consisting of two different P3AT blocks equipped with an H-donor and -acceptor functionality is presented. The P3ATs were synthesized using a functionalized Ni-initiator. By a series of postpolymerization reactions, including click chemistry, an H-donor and -acceptor entity was attached to the end of the polymer chains. Evidence for a quantitative functionalization of the polymers was provided by ¹H NMR and MALDI-ToF analyses. Chiral side chains were implemented on one of both blocks, allowing the study of the influence of the H-bond formation on the chiral self-assembly using UV–vis and circular dichroism spectroscopy