Poly[2,7‐(9,9‐dihexylfluorene)‐alt‐pyridine] with donor‐acceptor architectures: A new series of blue‐light‐emitting alternating copolymers

A novel series of well‐defined alternating poly[2,7‐(9,9‐dihexylfluorenyl)‐alt‐pyridinyl] (PDHFP) with donor‐acceptor repeat units were synthesized using palladium (0)‐catalyzed Suzuki cross‐coupling reactions in good to high yields. In this series of alternating polymers, 2, 7‐(9,9‐dihexylfluorenyl) was used as the light emitting unit, and the electron deficient pyridinyl unit was employed to provide improved electron transportation. These polymers were characterized by ¹H‐NMR and ¹³C‐NMR, gel permeation chromatography (GPC), thermal analyses, and UV‐vis and fluorescence spectroscopy. The glass transition temperature of copolymers in nitrogen ranged from 110 to 148 °C, and the copolymers showed high thermal stabilities with high decomposition temperatures in the range of 350 to 390 °C in air. The difference in linkage position of pyridinyl unit in the polymer backbone has significant effects on the electronic and optical properties of polymers in solution and in film phases. Meta‐linkage (3,5‐ and 2,6‐linkage) of pyridinyl units in the polymer backbone is more favorable to polymer for pure blue emission and prevention of aggregation of polymer chain than para‐linkage (2,5‐linkage) of the pyridinyl units. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4792–4801, 2004     

Two‐photon excitation and optical limiting in polyfluorene derivatives

Fluorene‐based polymers are widely known materials due to a combination of features such as photoluminescence and electroluminescence, oxidative stability, and film‐forming ability. However, studies reporting nonlinear optical properties in this class of conjugated polymer are scarce. Here, we report a new class of polyfluorene derivatives poly(9,9′‐n‐dihexyl‐2,7‐fluorenedilvinylene‐alt‐1,4‐phenylenevinylene), poly(9,9′‐n‐dihexyl‐2,7‐fluorenedilvinylene‐alt‐2,5‐thiophene), and poly[(9,9‐di‐hexylfluorenediylvinylene‐alt‐1,4‐phenylenevinylene)‐co‐((9,9′‐(3‐t‐butylpropanoate) fluorene‐1,4‐phenylene)] displaying high two‐photon absorption (2PA) in the spectral range from a 490 to 1100 nm. The 2PA cross‐section peak values for these materials are as high as 3000 Göppert Mayer (1 GM = 1 × 10^?50 cm⁴ s/photon), which is related to the high degree of conjugation along the polymer backbone. The polymers that were used in this study presented a strong two‐photon luminescence and also displayed optical limiting behavior, which, in combination with their well‐established properties, make them highly suitable for nonlinear optical devices. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 50: 148–153, 2012     

Synthesis and fluorescence properties of dysprosium‐coordinated with high‐Tg polyaryletherketones containing carboxyl side groups

A series of novel dysprosium coordination polymers were synthesized using new high‐T_g carboxyl‐containing polyaryletherketones (PEKs) as macromolecular ligands and a small molecule, 1,10‐phenanthroline, as co‐ligand. The FTIR, WAXD, and UV–Vis results indicated that the dysprosium ions were coordinated simultaneously with carboxyl group of PEKs and 1,10‐phenanthroline, and homogeneously distributed along the polymer backbone. These obtained dysprosium coordination polymers showed excellent film‐formation properties. Moreover, all the dysprosium coordination polymers could exhibit the intense characteristic emission of dysprosium ions under UV excitation. Meanwhile, the emission intensity increased with increasing dysprosium ion content, and no obvious fluorescence quenching happened at the Dy³⁺ ion content up to 10.71 wt%, which was attributed to the very rigid structure of PEK and synergistic coordination effect of PEK and 1,10‐phenanthroline. Copyright © 2009 John Wiley & Sons, Ltd.     

Poly(ether ketone)–polyisobutylene block copolymers: Synthesis and phase behavior

Telechelic poly(ether ketone)s (PEKs) and polyisobutylenes (PIBs) were combined to form PIB? PEK? PIB triblock copolymers and (PIB? PEK)_n multiblock copolymers via the formation of urea linkages. Monovalent and bivalent amino telechelic PIBs were prepared quantitatively from allyl telechelic PIBs by a newly developed reaction sequence featuring nucleophilic reaction steps. Telechelic PEK? NCO polymers were prepared from the corresponding amino telechelic PEKs via a reaction with diphosgene. The highly reactive PEK? NCO and PIB? NH₂ telechelics formed PEK? PIB block copolymers only quantitatively when appropriately reactive primary amino groups were present on the amino telechelic PIBs. The obtained block copolymers were microphase‐separated and featured mostly lamellar structures, as determined by small‐angle X‐ray scattering (SAXS). Temperature‐dependent SAXS measurements revealed ordered polymers in the melt up to 210 °C. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 188–202, 2005     

Optical and electronic properties of fluorene‐based copolymers and their sensory applications

A series of novel, fluorene‐based conjugated copolymers, poly[(9,9‐bis{propenyl}‐9H‐fluorene)‐co‐(9,9‐dihexyl‐9H‐fluorene)] ( P1 ), poly[(9,9‐bis{carboxymethylsulfonyl‐propyl}fluorenyl‐2,7‐diyl)‐co‐(9,9‐dihexyl‐9H‐fluorene)] ( P2 ) and poly[(9,9‐dihexylfluorene)‐co‐alt‐(9,9‐bis‐(6‐azidohexyl)fluorene)] ( P3 ), are synthesized by Suzuki coupling reactions and their electrochemical properties, in the form of films, are investigated using cyclic voltammetry. The results reveal that the polymer films exhibit electrochromic properties with a pseudo‐reversible redox behavior; transparent in the neutral state and dark violet in the oxidized state. Among the three polymers, P2 possesses the shortest response time and the highest coloration efficiency value. These polymers emit blue light with a band gap value of around 2.9 eV and have high fluorescent quantum yields. Their metal ion sensory abilities are also investigated by titrating them with a number of different transition metal ions; all of these polymers exhibit a higher selectivity toward Fe³⁺ ions than the other ions tested with Stern–Volmer constants of 4.41 × 10⁶M^?1, 3.28 × 10⁷M^?1, 1.25 × 10⁶M^?1, and 6.56 × 10⁶M^?1 for P1 , P2 , water soluble version of P2 ( P2S ) and P3 , respectively. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Synthesis and spectroscopic investigation of π‐conjugated (E)‐enyne polycarbazole with different organo‐metallic catalysts from 3,6‐diethynyl‐9‐(2‐ethylhexyl)carbazole

In the present study, a new (E)‐rich‐enyne π‐conjugated polymer containing a carbazole was designed and synthesized. Two different synthesis methods of poly[N‐(2‐ethylhexyl)‐3,6‐carbazolyleneethynylene‐(E)‐vinylene] (PCZEV) have been prepared from 3,6‐diethynyl‐9(2‐ethylhexyl)carbazole by using the palladium‐carbene‐catalyzed reaction and/or by using the organolanthanide‐catalyzed reaction leading to well‐defined polymer, and their general properties were studied. Compared to poly[N‐(2‐ethylhexyl)‐3,6‐carbazolyleneethynylene] (PCE), the UV‐vis absorption and photoluminescence of the PCZEV was red‐shifted, which indicates the extension of conjugation length. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2434–2442, 2009     

Nanocomposites derived from in situ grafting of linear and hyperbranched poly(ether‐ketone)s containing flexible oxyethylene spacers onto the surface of multiwalled carbon nanotubes

Linear and hyperbranched poly(ether‐ketone)s (PEKs) containing flexible oxyethylene spacers grafted multiwalled carbon nanotube (PEK‐g‐MWNT) nanocomposites were prepared by direct Friedel‐Crafts acylation as the polymer forming and grafting reaction. To achieve the composites, in situ polycondensations of AB monomers 3‐(2‐phenoxyethoxy)benzoic acid (3‐PEBA) and 4‐(2‐phenoxyethoxy)benzoic acid (4‐PEBA), and AB₂ monomer 3,5‐bis(2‐phenoxyethoxy)benzoic acid (3,5‐BPEBA) were carried out in the presence of multiwalled carbon nanotubes (MWNTs). The reaction conditions, polyphosphoric acid (PPA) with additional phosphorous phentoxide (P₂O₅) in the temperature range of 110–120 °C, were previously optimized. The conditions were used as the polymerization and grafting medium that were indeed benign not to damage MWNTs but strong enough to promote the covalent attachment of PEKs onto the surface of the electron‐deficient MWNTs. From scanning electron microscopy (SEM) and transmission electron microscopy studies, the polymers were uniformly grafted onto the MWNTs. The resultant nanocomposites are soluble in most strong acids such as trifluoroacetic acid, methanesulfonic acid, and sulfuric acid. Both isothermal and dynamic TGA studies in air showed that nanocomposites displayed improved thermo‐oxidative stability when compared with those of corresponding PEK homopolymers. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3471–3481, 2008     

Improved EL efficiency of fluorene‐thieno[3,2‐b]thiophene‐based conjugated copolymers with hole‐transporting or electron‐transporting units in the main chain

New electroluminescent polymers (poly(9,9′‐dioctylfluorene‐co‐thieno[3,2‐b]thiophene‐co‐benzo[2,3,5]thiadiazole) ( P1) and poly(9,9′‐dioctylfluorene‐co‐thieno[3,2‐b]thiophene‐co‐benzo[2,3,5]thiadiazole‐co‐[4‐(2‐ethylhexyloxyl)phenyl]diphenylamine ( P2) ) possess hole‐transporting or electron‐transporting units or both in the main chains. Electron‐deficient benzothiadiazole and electron‐rich triphenylamine moieties were incorporated into the polymer backbone to improve the electron‐transporting and hole‐transporting characteristics, respectively. P1 and P2 show greater solubility than poly(9,9′‐dioctylfluorene‐co‐thieno[3,2‐b]thiophene ( PFTT ), without sacrificing their good thermal stability. Moreover, owing to the incorporation of the electron‐deficient benzothiadiazole unit, P1 and P2 exhibit remarkably lower LUMO levels than PFTT , and thus, it should facilitate the electron injection into the polymer layer from the cathode electrode. Consequently, because of the balance of charge mobility, LED devices based on P1 and P2 exhibit greater brightness and efficiency (up to 3000 cd/m² and 1.35 cd/A) than devices that use the pristine PFTT . © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 243–253, 2006     

Relationship between the liquid crystallinity and field‐effect‐transistor behavior of fluorene–thiophene‐based conjugated copolymers

A series of fluorene–thiophene‐based semiconducting materials, poly(9,9′‐dioctylfluorene‐alt‐α,α′‐bisthieno[3,2‐b]thiophene) (F8TT2), poly(9,9′‐di(3,6‐dioxaheptyl)fluorene‐alt‐thieno[3,2‐b]thiophene) (BDOHF8TT), poly(9,9′‐di(3,6‐dioxaheptyl)fluorene‐alt‐bithiophene) (BDOHF8T2), and poly(9,9′‐dioctylfluorene‐co‐bithiophene‐co‐[4‐(2‐ethylhexyloxyl)phenyl]diphenylamine) (F8T2TPA), was synthesized through a palladium‐catalyzed Suzuki coupling reaction. F8TT2, BDOHF8TT, BDOHF8T2, and F8T2TPA films exhibited photoluminescence maxima at 523, 550, 522, and 559 nm, respectively. Solution‐processed field‐effect transistors (FETs) fabricated with all the copolymers except F8T2TPA showed p‐type organic FET characteristics. Studies of the differential scanning calorimetry scans and FETs of the polymers revealed that more crystalline polymers gave better FET device performance. The greater planarity and rigidity of thieno[3,2‐b]thiophene in comparison with bithiophene resulted in higher crystallinity of the polymer backbone, which led to improved FET performance. On the other hand, the random incorporation of the triphenylamine moiety into F8T2TPA caused the polymer chains to lose crystallinity, resulting in an absence of FET characteristics. With this study, we could assess the liquid‐crystallinity dependence of the field‐effect carrier mobility on organic FETs based on liquid‐crystalline copolymers. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4709–4721, 2006     

Synthesis of poly(5,6‐difluoro‐2,1,3‐benzothiadiazole‐alt‐9,9‐dioctyl‐fluorene) via direct arylation polycondensation

Poly(5,6‐difluoro‐2,1,3‐benzothiadiazole‐alt‐9,9‐dioctylfluorene) was successfully synthesized via direct arylation polycondensation of 5,6‐difluoro‐2,1,3‐benzothiadiazole and 2,7‐dibromo‐9,9‐dioctylfluorene. The reaction conditions were optimized, and a polymer with number‐average molecular weight (M_n) of 41,000 was obtained by using Pd(OAc)₂, P^tBu₂Me‐HBF₄, pivalic acid, K₂CO₃, and toluene as catalyst, ligand, additive, base, and solvent, respectively. The polycondensation was also performed with 5,6‐dioctyloxy‐2,1,3‐benzothiadiazole or 2,1,3‐benzothiadiazole as the comonomer, and the results indicate that the introduction of electron‐withdrawing fluorine atoms at the ortho‐positions to the C? H bonds is essential for the reactivity of the direct arylation. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2367–2374     

Polyaddition of bifunctional 1,3‐benzoxazine and 2‐methylresorcinol

A polyaddition system consisted of a bifunctional N‐n‐propyl benzoxazine and 2‐methylresorcinol ( MR ) that proceeds at ambient temperature has been developed. In this system, the aromatic ring of MR acted as a bifunctional monomer, reacting with a two equivalent amount of benzoxazine moieties via their ring‐opening reaction. The polyaddition gave the corresponding linear polymer bearing phenolic moieties bridged by Mannich‐type linkage in the main chain. The linear polymer had a high glass transition temperature, which was comparable to that of the linear polybenzoxazine synthesized by the ring‐opening polymerization of a monofunctional N‐n‐propyl benzoxazine. The employment of a bifunctional N‐allyl benzoxazine in the polyaddition system resulted in the formation of the corresponding polymer with allyl pendants, which exhibited improved heat resistance due to its thermally induced crosslinking reaction. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 3867–3872     

Characterization of two‐ and three‐photon absorption of polyfluorene derivatives

Fluorene‐based polymer derivatives are promising materials for organic electronic devices because of their photoluminescence and electroluminescence, good film‐forming ability, and favorable chemical and thermal properties. Although optical properties of polyfluorene have already been reported, most of the studies focused on the linear optical properties, whereas nonlinear optical characteristics have only recently received more detailed attention. Here, we report on two polyfluorene derivatives, poly(9,9′‐n‐dihexyl‐2,7‐fluorenediyl) (LaPPS 10) and poly(9,9′‐n‐dihexyl‐2,7‐fluorene‐diyl‐vinylene) (LaPPS 38), which present intense nonlinear absorption and fluorescence. Two‐photon absorption cross‐section properties of both polymers were characterized in the spectral range from 500 nm up to 900 nm, reaching peak values around 2000 Göppert Mayer units. Optical limiting behavior and two‐photon‐induced fluorescence of both polymers have also been investigated. Furthermore, the first molecular hyperpolarizability of the polymers was also studied using hyper‐Rayleigh scattering. In addition, the three‐photon absorption (3PA) spectra of both materials were also investigated, and 3PA cross‐section values in the order of 1 × 10^?78 cm⁶ s² photon^?2 were observed. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 747–754     

New blue electroluminescent n‐type polyfluorene copolymers with a 1,3,4‐oxadiazole unit in the main chain

Novel polyfluorene copolymers alternately having an 1,3,4‐oxadiazole unit in the main chain were prepared by both one‐step and two‐step methods for polyoxadiazole synthesis. They displayed highly efficient blue photoluminescence, the properties of which were affected by the extent of conjugation and the changes in the electron density by a side chain. An electrochemical analysis of the polymers using cyclic voltammetry suggested that they could be used as electron‐transport/hole‐blocking materials as well as blue emission materials for polymer light‐emitting diodes. A simple double‐layer device consisting of poly(N‐vinylcarbazole) as a hole‐transport layer and poly[(9,9′‐didodecylfluorene‐2,7‐diyl)‐alt‐((1,4‐bis(1,3,4‐oxadiazole)‐2,5‐di(2‐ethylhexyloxy)phenylene)‐5,5′‐diyl)] as an emission layer exhibited narrow blue electroluminescence with a maximum at 430 nm. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1058–1068, 2004     

Palladium on carbon‐catalyzed direct C—H arylation polycondensation of 3,4‐ethylenedioxythiophene with various dibromoarenes

We have demonstrated a direct arylation polycondensation of 3,4‐ethylenedioxythiophene with 2,7‐dibromo‐9,9‐dioctylfluorene using palladium on carbon (Pd/C) as a catalyst. Pd/C is a low‐cost solid‐supported palladium catalyst, giving one of the effective catalytic systems for direct arylation. The Pd/C‐catalyzed direct arylation polycondensation with acetic acid/potassium carbonate in N,N‐dimethylacetamide furnished a high molecular weight π‐conjugated alternating copolymer of EDOT‐fluorene (M_n = 89,300, M_w/M_n = 3.27) in high yield. The polycondensation of EDOT with various dibromoarenes was also achieved, giving EDOT‐carbazole, EDOT‐dialylamine, and EDOT‐bithiophene polymers. Optical and electrochemical properties of the polymers were also discussed. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 55, 1183–1188     

Recovery stress and work output in hyperbranched poly(ethyleneimine)‐modified shape‐memory epoxy polymers

In this study a series of hyperbranched modified shape‐memory polymers were subjected to constrained shape recoveries in order to determine their potential use as thermomechanical actuators. Materials were synthesized from a diglycidyl ether of bisphenol A as base epoxy and a polyetheramine and a commercial hyperbranched poly(ethyleneimine) as crosslinker agents. Hyperbranched polymers within the structure of the shape‐memory epoxy polymers led to a more heterogeneous network that can substantially modify mechanical properties. Thermomechanical and mechanical properties were analyzed and discussed in terms of the content of hyperbranched polymer. Shape‐memory effect was analyzed under fully and partially constrained conditions. When shape recovery was carried out with fixed strain a recovery stress was obtained whereas when it was carried out with a constraining stress the material performs mechanical work. Tensile tests at Tg^E′ showed excellent values of stress and strain at break (up to 15 MPa and almost 60%, respectively). Constrained recovery performances revealed rapid recovery stress generation and unusually high recovery stresses (up to 7 MPa) and extremely high work densities (up to 750 kJ/m³). The network structure of shape‐memory polymers was found to be a key factor for actuator‐like applications. Results confirm that hyperbranched modified‐epoxy shape memory polymers are good candidates for actuator‐like shape‐memory applications. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1002–1013     

Simple synthesis,photophysics, and electroluminescent properties of poly[2,7‐bis(4‐tert‐butylstyryl)fluorene‐9, 9‐diyl‐alt‐alkane‐α,ω‐diyl]

A simple synthetic route was used for the synthesis of a novel series of alternating copolymers based on substituted 2,7‐distyrylfluorene bridged through alkylene chains. First, 2,7‐dibromofluorene was reacted with 2 equiv of butyllithium, and this was followed by a treatment with 1 equiv of α,ω‐dibromoalkane to yield the intermediate, poly(2,7‐dibromofluorene‐9,9‐diyl‐alt‐alkane‐α,ω‐diyl). ( 1 ) Heck coupling of the latter with 1‐tert‐butyl‐4‐vinylbenzene afforded the target, poly[2,7‐bis(4‐tert‐butylstyryl)fluorene‐9,9‐diyl‐alt‐alkane‐α,ω‐diyl] ( 2 ). The two versions of 2 ( 2a and 2b which have hexane and decane, respectively, as alkane groups) were readily soluble in common organic solvents. Their glass‐transition temperature was relatively low (52 and 87 °C). An intense blue photoluminescence emission with maxima at about 408 and 409 nm was observed in tetrahydrofuran solutions, whereas thin films exhibited an orange emission with maxima at 569 and 588 nm. Very large redshifts of the photoluminescence maxima and Stokes shifts in thin films indicated strong aggregation in the solid state. Both polymers oxidized and reduced irreversibly. Single‐layer light‐emitting diodes with hole‐injecting indium tin oxide and electron‐injecting aluminum electrodes were fabricated. They emitted orange light with external electroluminescence efficiencies of 0.52 and 0.36% photon/electron, as determined in light‐emitting diodes made of 2a and 2b , with alkylenes of (CH₂)₆ and (CH₂)₁₀, respectively. An increase in the external electroluminescence efficiency up to 1.5% was reached in light‐emitting diodes made of polymer blends consisting of 2a and poly(9,9‐dihexadecylfluorene‐2,7‐diyl), which emitted blue‐white light. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 809–821, 2007.     

Electrically driven self‐healing polymers based on reversible guest–host complexation of β‐cyclodextrin and ferrocene

A multifunctional ferrocene‐modified poly(glycidyl methacrylate) (PGMA‐Fc) and a difunctional β‐cyclodextrin derivative (bis‐CD) has been prepared for the construction of an electrically driven removable and self‐healing polymeric materials based on the complexation reaction between ferrocene and β‐CD groups. The chemical structures of PGMA‐Fc and bis‐CD have been characterized with Fourier transform infrared, ¹H nuclear magnetic resonance, and X‐ray photoelectron spectroscopy. The effects of electrical voltages and medium conductivity on the decrosslinking efficiency of the crosslinked PGMA‐Fc/CD polymer have been examined. The PGMA‐Fc/CD network has shown removable feature and properties for application as a reworkable crosslinked material. Moreover, the crosslinked PGMA‐Fc/CD sample has shown electrically driven self‐healing behavior. The self‐healing performance could be enhanced with wetting the sample to increase the electrical conductivity. As a result, the material could serve as a self‐healing agent for commercial painting products. Preparation and application of a novel and efficient self‐healing polymer have been demonstrated. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 3395–3403     

Synthesis of high molecular weight trans‐poly(9,9‐di‐n‐octylfluorene‐2,7‐vinylene) by the acyclic diene metathesis polymerization using molybdenum catalysts

High molecular weight trans‐poly(9,9‐di‐n‐octylfluorene‐2,7‐vinylene) was prepared under reduced pressure in the presence of a well‐defined Schrock‐type catalyst, Mo(CHCMe₂Ph)(N‐2,6‐Me₂C₆H₃)[OCMe(CF₃)₂]₂, in toluene. The effect of initial monomer concentration was found to be an important factor for preparing high molecular weight polymers with unimodal molecular weight distributions. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2463–2470, 2001     

Energy transfer in poly(3‐hexylthiophene)‐g‐Polyfluorene graft copolymers

Conjugated graft copolymers consisting of a poly(3‐hexylthiophene) (P3HT) backbone and poly(9,9'‐dioctylfluorene) side chains (PF) with different grafting degrees were synthesized by the CuAAC reaction. The properties of these materials were studied by UV‐Vis and fluorescence spectroscopy. The former technique provides insight in their self‐assembly, while the latter is used to study the energy funneling from the PF side chains to the P3HT backbone. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1252–1258