Grignard Metathesis Polymerization Research Articles

Imidazolium-substituted ionic (co)polythiophenes: Compositional influence on solution behavior and thermal properties

A series of ionic polythiophenes, in homopolymer and random copolymer configurations, is prepared via the Grignard metathesis (GRIM) polymerization protocol and subsequent substitution on the bromohexyl side chains with N-methylimidazole. The introduced structural variations – comonomer ratio, side chain composition, counter ions – allow tuning of the thermal properties and solution behavior of the resulting conjugated polymers. As expected, the solubility depends majorly on the number of ionic groups and the counter ions. The most peculiar behavior is observed for the P3HT-P3(MIM)HT-Br 50/50 random copolymer, which shows organization of the polymer chains in solution and thin film dependent on the preparation conditions. Dynamic light scattering studies confirm that the ordered solid-state structure is somewhat maintained when the copolymer is dissolved in a bad solvent mixture. The ionic (co)polythiophenes are generally more resistant to thermal degradation than their precursors. The precursor polymers all show a clear semi-crystalline behavior, with a decrease in crystallinity upon decreasing the number of regular 3-hexylthiophene units. On the other hand, the studied ionic (co)polythiophenes are fully amorphous. Changes in the counter ions have dramatic effects on the thermal properties. Bromine counter ions render the polymers strongly hygroscopic. The novel materials are of particular appeal in the field of organic photovoltaics, in which the imidazolium-substituted (co)polythiophenes can be beneficially applied as constituents of either active layers or electron transport layers. Their processability from green solvents is also of major importance for the field.

Self-Assembly of Diblock Polythiophenes with Discotic Liquid Crystals on Side Chains for the Formation of a Highly Ordered Nanowire Morphology

Diblock copolymers bearing a triphenylene (TP) discotic liquid crystals moiety, poly(3-hexylthiophene)-block-poly[3-(10-(2,3,6,7,10-pentakis(hexyloxy)triphenylen)-decyloxy)thiophene] (P3HT-b-P3TPT), was successfully synthesized by Grignard metathesis polymerization. The self-assembled nanowire structures of these diblock copolymers have been investigated by atomic force microscopy and transmission electron microscopy. The domain size and crystallinity of the nanostructures can be easily controlled by tuning the P3HT/P3TPT block ratio and by employing different annealing processes such as thermal and solvent annealing. The results of X-ray diffraction indicate that both intermolecular interactions and mesogen packing are essential for the formation of nanostructures in the diblock copolymers. Although the block ratio of P3HT and P3TPT comes to 9:1 and the copolymer undergoes solvent annealing followed by thermal treatment, an optimal crystalline nanowire with a size of 16.9 nm is formed. In addition, solar cells based on these copolymers as electron donors in combination with [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) or N,N'-di(2-ethylhexyl)perylene-3,4,9,10-tetracarboxylbisimide (PDI) as electron acceptors have been constructed, and the effect of the nanomorphology on device performance has been investigated.

Synthesis of poly(3‐hexylthiophene)‐block‐poly(ethylene)‐block‐poly(3‐hexylthiophene) via a combination of ring‐opening olefin metathesis polymerization and grignard metathesis polymerization

ABSTRACTNovel rod–coil–rod ABA triblock copolymers, poly(3‐hexylthiophene)‐block‐poly(ethylene)‐block‐poly(3‐hexylthiophene) (P3HT‐b‐PE‐b‐P3HT) were synthesized by using a combination of a Ru‐catalyzed ring‐opening metathesis polymerization of 1,4‐cyclooctadiene in the presence of a suitable chain transfer agent (CTA) and a Ni‐catalyzed Grignard metathesis polymerization of 5‐chloromagnesio‐2‐bromo‐3‐hexylthiophene followed by hydrogenation. Using this methodology, the molecular weights of the poly(butadiene) (PBD) or the P3HT blocks were controlled by adjusting the initial monomer/CTA or the initial monomer/macroinitiator ratio, respectively. In addition, the triblock structure was confirmed by selective oxidative degradation of the PBD block found in the intermediate P3HT‐b‐PBD‐b‐P3HT copolymer produced in the aforementioned method, followed by analysis of the degradation products. Thermal analysis and atomic force microscopy of P3HT‐b‐PE‐b‐P3HT revealed that the material underwent phase separation in the solid state, a feature which may prove useful for improving charge mobilities within electronic devices. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3810–3817

One‐pot synthesis of conjugated poly(3‐hexylthiophene)‐b‐poly(phenyl isocyanide) hybrid rod–rod block copolymers and its self‐assembling properties

ABSTRACTIn this article, the synthesis of a series of conjugated rod–rod block copolymers based on poly(3‐hexylthiophene) (P3HT) and poly(phenyl isocyanide) (PPI) building blocks in a single pot is presented. Ni‐catalyzed Grignard metathesis polymerization of 2,5‐dibromo‐3‐hexylthiophene and subsequent addition of 4‐isocyanobenzoyl‐2‐aminoisobutyric acid decyl ester in the presence of Ni(dppp)Cl2 as a single catalyst afford P3HT‐b‐PPI with tunable molecular weights and compositions. In solid state, microphase separation occurred as differential scanning calorimetric analysis of P3HT‐b‐PPI revealed two glass transition temperatures. In solutions, the copolymers can self‐assemble into spherical aggregates with P3HT core and PPI shell in tetrahydrofuran and exhibit amorphous state in CHCl3. However, atomic force microscopy revealed that the block copolymers self‐assemble into nanofibrils on the substrate. These unique features warrant the resultant conjugated rod–rod copolymers' potential study in organic photovoltaic and other electronic devices. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2939–2947

Conducting Polymer/SWCNTs Modular Hybrid Materials via Diels–Alder Ligation

The development of a facile covalent strategy for the fabrication of organic conducting polymers (OCPs)/carbon nanotubes (CNTs) based molecular hybrid materials remains a challenge and is expected to address the detrimental intrinsic bundling issue of CNTs. In view of the pristine CNTs’ ability to undergo Diels–Alder reactions with dienes, we report the synthesis of a novel poly(3-hexylthiophene) (P3HT) based organic conducting polymer (OCP) with terminal cyclopentadienyl (Cp) groups. The synthetic strategy employed is based on a combination of in situ end group functionalization via Grignard metathesis (GRIM) polymerization and a subsequent end group switching via reaction with nickelocene. Characterization data from Matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI–TOF MS) fully support the successful synthesis of monofunctional Cp-capped P3HT, which was found to be highly reactive toward dienophile end-capped polystyrene (PS). The Cp-capped P3HT was subsequently ligated to the surface of pristine single walled CNTs (SWCNTs). The resulting P3HT/SWCNTs molecular hybrid material was characterized using thermogravimetric analysis (TGA), elemental analysis (EA), X-ray photoelectron spectroscopy (XPS), and high resolution transmission electron microscopy (HRTEM). The data from TGA, EA, and XPS were used to quantitatively deduce the grafting density. P3HT/SWCNTs prepared with Cp capped P3HT was found to contain 2 times more P3HT than the reference sample, featuring a grafting density of 0.0510 chains·nm–2 and a periodicity of 1 P3HT chain per 748 carbon atoms of the SWCNTs. HRTEM revealed individual SWCNTs wrapped with P3HT whereas in the reference sample P3HT was adsorbed on the bundles of the SWCNTs. The results presented here provide a new avenue for designing novel materials based on CNTs and OCPs.

Self-Organized Hole Transport Layers Based on Polythiophene Diblock Copolymers for Inverted Organic Solar Cells with High Efficiency

Novel fluoroalkyl side-chain diblock copolymers, poly(3-hexylthiophene)-block-poly[3-(4-(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyloxy)phenyl)decyloxy)thiophene] (P3HT-b-P3FAT), were successfully synthesized by Grignard metathesis (GRIM) polymerization. Driven by the low surface energy of fluoroalkyl side chains, the fluorinated polymers can spontaneously segregate on the surface of poly-(3-hexylthiophene) (P3HT) during spin-coating processes. As the P3HT block increases in the copolymer, higher concentrations of fluoropolymers are required to form the self-assembled monolayer on the surface. The fluorinated part forms an interfacial dipole that shifts the work function of the anode metal, while the P3HT block can interact with the P3HT donor for hole transport. With this self-assembly hole transport layer to align the energy levels, P3HT:PCBM photovoltaic devices are easily fabricated to achieve improved performance. Overall, devices prepared with 1.5 mg mL–1 copolymer PFT-3HT with a 3:1 ratio of P3HT to P3FAT block in the active layer solution displayed PCE values of up to 4.6% (50% PCE increase over a PEDOT:PSS control device) and showed a significant long-term stability in excess of 300 h in air.

Precision synthesis of tailor-made polythiophene-based materials and their application to organic solar cells

Polymer-based solar cells (PSCs) have been promising candidates as renewable energy resources, having multiple advantages of flexible, low-cost and large-area processing for their mass production. Among them, much attention has been paid to fundamental bulk-heterojunction (BHJ) devices using a blend of regioregular poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as the active layer. However, there are still significant limitations not only in the low power conversion efficiency (PCE), but also in the device stability. The morphological control of BHJ PSCs is one of the most important issues to improve the device performances. On the other hand, P3HT itself has received much attention in many fields, because it is the best class of balanced high-performance materials as a p-type semiconductor in terms of solubility, chemical stability, charge mobility, and commercial availability. The discovery of the quasi-living Grignard metathesis polymerization (or called catalysttransfer polycondensation) system has made it possible to synthesize a wide variety of chain-end-functional P3HT derivatives, their block copolymers and star-branched polymers. Since the competitive research areas including PSC applications have strongly demanded the accelerated developments of new materials and well-defined morphologies related to polythiophenes, the fundamental studies of P3HT have still been targeted by many research groups. In this review, the controlled synthesis of P3HT, the synthesis of P3HT-based block copolymers, their applications to PSCs, as well as the scope and potential of new thiophene-based materials are described.

Facile synthesis for well-defined A2B miktoarm star copolymer of poly(3-hexylthiophene) and poly(methyl methacrylate) by the combination of anionic polymerization and click reaction

We have introduced a facile synthetic route for well-defined A2B miktoarm star copolymer composed of regioregular poly(3-hexylthiophene) and poly(methyl methacrylate) ((P3HT)2PMMA) by the combination of anionic polymerization and click reaction. First, we synthesized PMMA terminated with 1,3,5-tris(bromomethyl)benzene (PMMA-(Br)2) by anionic polymerization, and two bromines attached to the end of the PMMA chains were replaced by azides (PMMA-(N3)2). Also, monoethynyl-capped P3HT was synthesized by Grignard metathesis polymerization and post-end functionalization. Then, copper(I)-catalyzed Huisgen 1,3-dipolar cycloaddition click reaction between monoethynyl-capped P3HT and PMMA-(N3)2 was performed to synthesize (P3HT)2PMMA. We used a slightly excess amount of monoethynyl-capped P3HT so that all of the azide groups at the end of the PMMA chains completely reacted with monoethynyl-capped P3HT. After complete removal of unreacted monoethynyl-capped P3HT by column chromatography, pure (P3HT)2PMMA with narrow molecular weight distribution (the polydispersity of 1.18) was obtained. The weight fraction of P3HT and the total molecular weight of (P3HT)2PMMA are 0.48 and 16,000, respectively. To investigate the effect of the chain architecture on optical property and thin-film morphology, we synthesized two linear P3HT-b-PMMAs (P3HT-b-PMMA-L and P3HT-b-PMMA-H) with similar weight fraction of P3HT block (0.48 for P3HT-b-PMMA-L and 0.45 for P3HT-b-PMMA-H) but two different total molecular weights (7900 for P3HT-b-PMMA-L and 15,300 for P3HT-b-PMMA-H). UV–visible (UV–vis) absorption spectrum and the fibril width of (P3HT)2PMMA thin film were similar to those of P3HT-b-PMMA-L thin film. However, UV–vis spectrum for P3HT-b-PMMA-H thin film was red-shifted and the fibril width of P3HT-b-PMMA-H was much larger than that of (P3HT)2PMMA. This indicates that the π–π interaction between P3HT arms in (P3HT)2PMMA is strong enough to arrange two P3HT backbone chains in (P3HT)2PMMA to stack one by one along the nanofibril axis. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013

Synthesis, Characterizations, and Morphological Studies of Polyoxometalate‐Containing Rod–Coil Diblock Copolymers

AbstractA set of hybrid rod–coil diblock copolymers containing different sizes of poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) as the rod block and a polystyryl‐type (PS) coil block with covalently linked polyoxometalates (POMs) as side chains have been synthesized. The P3HT rod blocks, synthesized using Grignard metathesis polymerization, and the PS coil block, prepared by atom transfer radical polymerization were successfully coupled using “click” chemistry to form the rod–coil diblock copolymers (PS‐PTn). POM cluster attachment was performed on the diblock copolymers through a post‐polymerization functionalization approach. The thin film morphology of the diblock copolymers prior to cluster attachment shows a strong dependence on the solvent and the size of the P3HT block. Following cluster attachment, the hybrid diblock copolymers show much less solvent and size dependence in phase‐separated morphologies of their pristine films. The sporadic and isolated conducting domains seen in the pristine films change to widespread worm‐like conducting networks after thermal annealing; such morphologies are conducive to photovoltaic properties.

Role of the transition metal in Grignard metathesis polymerization (GRIM) of 3-hexylthiophene

Regioregular poly(3-alkylthiophene)s are widely used in organic electronics applications such as solar cells and field effect transistors. Nickel, palladium, and platinum diphenylphosphinoethane complexes were tested as catalysts for the Grignard metathesis (GRIM) polymerization of 2,5-dibromo-3-hexylthiophene and 2-bromo-5-iodo-3-hexylthiophene. Nickel-mediated polymerization generated regioregular, low-polydispersity poly(3-hexylthiophene) with well-defined molecular weight consistent with a “living” chain-growth mechanism. By contrast, palladium-mediated polymerization proceeded by a step-growth mechanism and generated polymers with less than 80% head-to-tail couplings. Platinum-mediated polymerization gave very low molecular weight products. Kinetic and computational results suggested that the nickel catalyst acts as an initiator and remains associated with the growing polymer chain, while palladium dissociates from the growing chain. Computational and experimental evidence was provided for various side reactions of dissociated Pd(0) catalyst, which could yield a step growth mechanism and lower regioirregularity.

Amphiphilic poly(alkylthiophene) block copolymers prepared via externally initiated GRIM and click coupling

Block copolymers with a poly(3-alkylthiophene) (P3AT) polymer block can self-organize into periodic, crystalline nanostructures that may be useful for organic electronic applications. However, reliable synthetic methods for the preparation of P3AT block copolymers are lacking. Here, we demonstrate a general method for the synthesis of P3AT rod-coil block copolymers via click-coupling of alkynyl-P3AT. Alkynyl-P3ATs are prepared via externally initiated Grignard metathesis polymerization (GRIM) using a modified nickel catalyst followed by end-group modification. The resulting alkynyl-P3ATs have improved stability and solubility compared with those previously reported. P3ATs are subsequently coupled to an azide-functionalized poly(ethylene glycol) through copper-catalyzed azide–alkyne click coupling, resulting in P3AT-b-PEG block copolymers. The advantages of this synthetic procedure are the improved stability of the alkynyl-P3AT macroreagent, the capability to synthesize high molecular weight P3AT polymer blocks, and facile determination of P3AT absolute molecular weight through 1H NMR analysis. This synthetic method is applied to prepare a series of P3AT-b-PEG block copolymers, with poly(3-hexyl thiophene) (P3HT), poly(3-dodecylthiophene) (P3DDT), and poly(3-(2′-ethyl)hexylthiophene) (P3EHT) polymer blocks. The resulting P3AT block copolymers are dispersed in water to form micelles with crystalline, hydrophobic cores. Absorbance measurements show that crystallization of P3DDT and P3EHT blocks is suppressed in micellar cores due to nanoscale confinement of the P3AT blocks.

Correction to In Situ Formation of Pyridyl-Functionalized Poly(3-hexylthiophene)s via Quenching of the Grignard Metathesis Polymerization: Toward Ligands for Semiconductor Quantum Dots

ADVERTISEMENT RETURN TO ISSUEPREVAddition/CorrectionNEXTORIGINAL ARTICLEThis notice is a correctionCorrection to In Situ Formation of Pyridyl-Functionalized Poly(3-hexylthiophene)s via Quenching of the Grignard Metathesis Polymerization: Toward Ligands for Semiconductor Quantum DotsW. Michael Kochemba, Deanna L. Pickel*, Joseph D. Keene, Sandra J. Rosenthal, Bobby G. Sumpter, Jihua Chen, and S. Michael Kilbey, II*Cite this: Chem. Mater. 2013, 25, 1, 113Publication Date (Web):December 20, 2012Publication History Published online20 December 2012Published inissue 8 January 2013https://doi.org/10.1021/cm303907tCopyright © 2012 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views474Altmetric-Citations1LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (106 KB) Get e-Alerts Get e-Alerts

All-Polymer Solar Cells Based on Fully Conjugated Block Copolymers Composed of Poly(3-hexylthiophene) and Poly(naphthalene bisimide) Segments

Fully conjugated donor–acceptor block copolymers composed of poly(3-hexylthiophene) and poly(naphthalene bisimide) segments, P3HT-PNBI-P3HTs, were synthesized using quasi-living Grignard metathesis polymerization and the Yamamoto coupling reaction. Broad absorption in a range of 350–850 nm, which corresponded to the optical band gap of 1.46 eV, was observed for the P3HT-PNBI-P3HT thin films. In addition, the optical band gap decreased to 1.38 eV (the light absorption band extended to 893 nm) by thermal annealing, which was much smaller than those of previously reported donor–acceptor block copolymers (1.6–1.8 eV). The annealed P3HT:P3HT-PNBI-P3HT blend film (1:1 by weight) also exhibited broad absorption in the range of 350–950 nm. Cyclic voltammetry demonstrated that the P3HT-PNBI-P3HT thin films exhibited the oxidation and reduction properties derived from the P3HT and PNBI segments. The HOMO and LUMO levels were in the range of 5.57–5.60 and 4.22–4.27 eV, respectively. All-polymer solar cells using the...

Synthesis and Postfunctionalization of Rod–Coil Diblock and Coil–Rod–Coil Triblock Copolymers Composed of Poly(3-hexylthiophene) and Poly(4-(4′-N,N-dihexylaminophenylethynyl)styrene) Segments

Poly(3-hexylthiophene) (P3HT) with a bromobutyl functional group at the ω-chain-end (P3HT-C4Br) and P3HT with bromobutyl functional groups at the α,ω-chain-ends (BrC4-P3HT-C4Br) were synthesized by selecting the appropriate initiators for the Grignard metathesis (GRIM) polymerization. The high end-functionality was confirmed by matrix assisted laser desorption-ionization time-of-flight (MALDI–TOF) mass spectrometry. These polymers were efficiently reacted with the living anionic polymers of 4-(4′-N,N-dihexylaminophenylethynyl)styrene (DHPS) to yield novel rod–coil diblock and coil–rod–coil triblock copolymers composed of rigid P3HT and flexible poly(4-(4′-N,N-dihexylaminophenylethynyl)styrene) (PDHPS) segments. The expected structures of the block copolymers were confirmed by size exclusion chromatography (SEC), proton nuclear magnetic resonance (1H NMR), and Fourier transform infrared (FT-IR) spectroscopies. Furthermore, the side chain alkynes of the PDHPS segments of both P3HT-b-PDHPS and PDHPS-b-P3HT-b-PDHPS were quantitatively functionalized by a [2 + 2] cycloaddition followed by a cycloreversion with tetracyanoethylene (TCNE), producing the corresponding block copolymers with donor–acceptor moieties in the flexible polystyrene segments. The formation of the new chromophores was confirmed by UV–vis spectroscopy and cyclic voltammetry (CV), which revealed strong intramolecular charge-transfer bands and redox activities ascribed to the formed donor–acceptor moieties. The thermal properties and surface morphology of the block copolymers were also evaluated by differential scanning calorimetry (DSC), atomic force microscopy (AFM) observations, and small-angle and wide-angle X-ray scattering (SAXS and WAXS). This is the first report about the development of P3HT-based block copolymers with tunable optoelectronic properties, which was achieved by the combined synthetic techniques of the GRIM polymerization, living anionic polymerization, and click postfunctionalization.

In Situ Formation of Pyridyl-Functionalized Poly(3-hexylthiophene)s via Quenching of the Grignard Metathesis Polymerization: Toward Ligands for Semiconductor Quantum Dots

The synthesis of well-defined, end-functional poly(3-hexylthiophene)s (P3HTs) by in situ quenching of the Grignard metathesis (GRIM) polymerization is complicated by the extreme tendency to favor difunctional products in all but a few cases. A facile one-pot method for preparing 2-pyridyl and 3-pyridyl P3HTs with high abundance of monofunctional products is established via an examination of the kinetics of the end-functionalization quenching reaction with lithium chloride complexes of 2- and 3-pyridyl Grignard reagents. Density functional theory calculations guide the selection of pyridine as the end group, which provides the capacity to ligate cadmium selenide (CdSe) nanocrystals and arrests aggregation upon thermal annealing when dispersed in a P3HT matrix. The relative abundances of various end-functional products, as ascertained by high-resolution matrix assisted laser desorption ionization time-of-flight mass spectrometry, can be altered through the use of 1-pentene as an additive: GRIM polymerizations quenched with 3-pyridyl and 2-pyridyl Grignard reagents show 5% and 18% abundances of difunctional, pyridyl-capped P3HTs, respectively, when 1-pentene is present at 1000:1 relative to the nickel catalyst. This represents a significant improvement compared to quenching with aryl Grignard reagents, where difunctional products predominate. The ability to manipulate end group compositions coupled with the propensity of pyridyl-functionalized P3HTs to ligate semiconductor quantum dots (SQDs) opens new possibilities for tuning the morphology of conjugated polymer/SQD blends.

Morphology Control in TiO2 Nanorod/Polythiophene Composites for Bulk Heterojunction Solar Cells Using Hydrogen Bonding

Hydrogen bond interactions between a dye adsorbed at the interface of TiO2 nanorods and functionalized P3HT was used to control nanorod dispersion, increase interfacial area, and improve efficiency in solution-processable hybrid bulk heterojunction solar cells. A series of poly(3-hexylthiophene-b-ethylene glycol) (P3HT-b-PEG) copolymers were prepared by a combination of Grignard metathesis polymerization and click chemistry. The short PEG segments in P3HT-b-PEG serve as a hydrogen bond acceptor. TiO2 nanorods functionalized with N3-dye bearing multiple COOH groups function as both the electron acceptor and hydrogen bond donor. The strong preferential H-bonding interaction between TiO2 nanorods and the PEG chain limits the aggregation of the TiO2 nanorods and affords homogeneously dispersion of the nanorods within the polymer matrix to form an interpenetrating network. This structure provides large interfacial area between electron donor and acceptor and highly efficient transport pathways within the compo...

Thermally Induced Coupling of Poly(thiophene)-Based Block Copolymers Prepared by Grignard Metathesis Polymerization: A Straightforward Route toward Highly Regioregular Multiblock Conjugated Copolymers

We report on a convenient and simple process to prepare highly regioregular poly(thiophene)-based multiblock copolymers by a novel thermally induced coupling reaction. Diblock copolymers of 3-hexylthiophene (3HT) and 2,5-dibromo-3-(2-(2-tetrahydropyranyl-2-oxy)ethyl)thiophene (THPET) end-capped by a nickel complex (Br-P3HT-b-PTHPET-Ni(dppp)Br) are first prepared using Ni(dppp)Cl2 as catalyst at 30 °C by Grignard metathesis polymerization (GRIM process). The coupling of these α-bromo, ω-Ni(dppp)Br telechelic diblock copolymers then occurs by heating the solution of the copolymer at 80 °C for a few hours without adding any additional reagent. Reactions are complete in only 10 min when heating the copolymer at 120 °C using microwaves. The deprotection of the alcohol groups of PTHPET blocks allows further modifications such as the incorporation of acrylates by esterification. AFM analysis on thin films shows the influence of the nature of side chains (protected alcohol or acrylate), the molecular weight, and the architecture (diblock or multiblock) of the copolymer on the supramolecular organization of the polythiophene chains.

Synthesis, Structures, and Hydroboration of Oligo- and Poly(3-alkynylthiophene)s

3-Alkynyl-substituted terthiophenes and polythiophenes were synthesized, and their properties and behavior toward hydroboration with Mes2BH were investigated. The alkynyl-substituted terthiophene was found to crystallize in an intriguing layered structure that mimics an interdigitated polymer wherein the terthiophenes form tightly π-stacked linear pseudopolymer strands. The heptynyl side chains of neighboring stacks interlock ideally, almost completely filling the void in-between substituents and thus allowing for minimal spacing between neighboring pseudopolymer strands. Poly(3-alkynylthiophene)s were accessed through Grignard metathesis polymerization (GRIM) of 2,5-dibromo-3-heptynylthiophene, which yielded polymers of moderate molecular weights (Mn = 6.3; PDI = 1.73) in yields of up to 82%. Further modification by hydroboration with Mes2BH resulted in a material that is partially functionalized with vinylborane groups and as a result exhibits charge transfer bands in the UV–vis spectra. A single-crystal X-ray structure of the corresponding hydroborated terthiophene species shows extensive intermolecular interactions, resulting in π-stacks of π-dimers, despite the steric bulk of the dimesitylborane moieties.

Synthesis, photophysical properties and microphase separation of all‐conjugated diblock copolymers with hydrophilic side chains

AbstractA series of new all‐conjugated diblock copolymers, poly(2,5‐dioctyloxy‐p‐phenylene)‐block‐poly(3‐methoxyethoxyethoxy‐methylthiophene) (PPP‐b‐P3MEEMT), with hydrophilic side‐chains have been synthesized by quasi‐living Grignard metathesis polymerization. The narrow polydispersity indices of the block copolymers are in the range 1.32–1.40. The block ratios in the obtained diblock copolymers can be well defined by the feed ratios of the monomers. Photoluminescence results reveal that resonance energy transfer occurs from the PPP block to the P3MEEMT block in dilute solution. Differential scanning calorimetry shows that both PPP and P3MEEMT blocks in the copolymers produce crystalline regions and lead to microphase separation as indicated by two endothermal transitions, corresponding to the melting peaks of the PPP and P3MEEMT blocks, respectively. The formations of microphase‐separated nanostructures in annealed copolymer films are also observed using transmission electron microscopy. © 2012 Society of Chemical Industry

End-group stannylation of regioregular poly(3-hexylthiophene)s

Mono- and bis-stannylation at the chain ends of regioregular poly(3-hexylthiophene) (P3HT) were conducted by post-functionalization of P3HT synthesized through Ni-catalyzed Grignard metathesis polymerization. Lithiation of P3HT with s-BuLi and subsequent stannylation with Me3SnCl led to the formation of bis-stannylated P3HT. The highest conversion of 81% was achieved with the additive N,N,N′,N′-tetramethylethylenediamine (TMEDA), which could enhance the stability of the lithiated compound. On the other hand, mono-stannylated P3HT was synthesized without contamination by bis-stannylated P3HT through successive reactions with a Grignard reagent and Me3SnCl.