Synthesis of oxadiazole‐based polymers containing a carbazole–vinylene or fluorene–vinylene group and their hole‐injection/transport behavior in light‐emitting diodes

A series of conjugated (poly{N‐(2‐ethylhexyl)‐3,6‐carbazole–vinylene‐alt‐[(2,5‐bisphenyl)‐1,3,4‐oxadiazole]}) and nonconjugated (poly{N‐(2‐ethylhexyl)‐3,6‐carbazole–vinylene‐alt‐[(2,5‐bisphenol)‐1,3,4‐oxadiazole]}) and poly{9,9‐dihexyl‐2,7‐fluorene–vinylene‐alt‐[(2,5‐bisphenol)‐1,3,4‐oxadiazole]}) polymers containing oxadiazole and carbazole or fluorene moieties in the polymer backbone were synthesized with a multiple‐step procedure. The properties of the polymers, including the photophysical and electrochemical characteristics, could be fine‐tuned by adjustment of the components or structures in the polymer chains. The polymers were used to examine the hole‐injection/transport behavior as hole‐injection/hole‐transport layers in double‐layer indium tin oxide (ITO)/polymer/aluminum tris(8‐hydroxyquinoline)/LiF/Al devices by the determination of their energy levels. The effects of the polymers in these devices on the charge‐transport behavior were compared with a control device fabricated with poly(ethylenedioxythiophene) (PEDOT)–poly(styrene sulfonate) (PSS). Devices containing the synthesized polymers showed comparable adhesion to the ITO anode and good hole‐injection/transport performance. In addition, they exhibited higher electroluminescence over an identical range of current densities than the control device. This was attributed to the prevention of radiative exciton quenching caused by the PEDOT–PSS interfaces and the improvement of electron/exciton blocking due to the higher electron affinity of the synthesized polymers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and characterization of novel phenyl‐substituted poly(p‐phenylene vinylene) derivatives

Two novel phenyl‐substituted poly(p‐phenylene vinylene) derivatives, poly{2‐[3′,4′‐(2″‐ethylhexyloxy)(3″,7″‐dimethyloctyloxy)benzene]‐1,4‐phenylenevinylene} (EDP‐PPV) and poly{2‐[3′,4′‐(2″‐ethylhexyloxy)(3″,7″‐dimethyloctyloxy)benzene]‐5‐methoxy‐1,4‐phenylenevinylene} (EDMP‐PPV), and their copolymer, poly{2‐[3′,4′‐(2″‐ethylhexyloxy)(3″,7″‐dimethyloctyloxy)benzene]‐1,4‐phenylene‐vinylene‐co‐2‐[3′,4′‐(2″‐ethylhexyloxy)(3″,7″‐dimethyloctyloxy)benzene]‐5‐methoxy‐1,4‐phenylenevinylene} (EDP‐co‐EDMP‐PPV; 4:1, 1:1, and 1:4), were successfully synthesized according to the Gilch route. The structures and properties of the monomers and the resulting conjugated polymers were characterized with ¹H‐NMR, ¹³C‐NMR, elemental analysis, gel permeation chromatography, thermogravimetric analysis, ultraviolet–visible absorption spectroscopy, and photoluminescence and electroluminescence (EL) spectroscopy. The EL polymers possessed excellent solubility in common solvents and good thermal stability with a 5% weight loss temperature of more than 380°C. The weight‐average molecular weights and polydispersity indices of EDP‐PPV, EDMP‐PPV, and EDP‐co‐EDMP‐PPV were 1.40–2.58 × 10⁵, and 1.19–1.52, respectively. Double‐layer light‐emitting diodes with the configuration of indium tin oxide/polymer/tris(8‐hydroxyquinoline)aluminum/Al devices were fabricated, and EDP‐co‐EDMP‐PPV (1:1) showed the highest EL performance and exhibited a maximum luminance of 1050 cd/m² at 19.5 V. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1259–1266, 2005     

Novel 2,4‐divinyl‐3‐alkylthiophene/1,3,4‐oxadiazole alternating conjugated copolymer synthesized by the Heck coupling method: Synthesis,characterization, and electronic and optical properties

A novel alternating copolymer with 3‐alkylthiophene and oxadiazole (or pyridine) units in ordered arrangement was synthesized with vinyl as a bridge for the first time. The synthesis process included four steps: bromomethylation, preparation of the ylide monomer, the formation of 2,4‐divinyl‐3‐alkylthiophene, and Heck alternating copolymerization. The Fourier transform infrared spectroscopy, ¹H‐NMR, and gel permeation chromatography measurements showed that all of the copolymers had the required structures. The weight‐average molecular weights of the copolymers were in the range 5500–15,000 with a relatively low polydispersity index of 1.4–1.7. The solubility of the copolymers in common solvents (e.g., methylene chloride, chloroform, tetrahydrofuran) was excellent. The optical properties and bandgap of the copolymers was compared with corresponding poly(3‐alkylthiophene) homopolymers. The photoluminescence quantum efficiency (QE) of the copolymers improved markedly in chloroform. The QEs of poly(2,4‐divinyl‐3‐hexylthiophene‐alt‐2,5‐diphenyl‐1,3,4‐ oxadiazole) and poly(2,4‐divinyl‐3‐octythiophene‐alt‐2,5‐diphenyl‐1,3,4‐oxadiazole) were 43.2 and 34.2%, respectively, which were about 20 and 21 times higher than those of the homopolymers, respectively. The ionization potential of the copolymers between 5.53 and 6.13 eV was appropriated to poly(3‐alkylthiophene)s. The high electron affinity of the copolymers (2.71–2.95 eV) made the electrons inject from the cathode more easily. With excellent solubility, low bandgap energy, high QE, and both electron‐transporting and hole‐transporting abilities, the proposed copolymers might be excellent polymeric materials for applications in polymer light‐emitting diodes, light‐emitting electrochemical cells, and polymer solar cells. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and properties of partially conjugated hyperbranched light‐emitting polymers

Via A₂ + B₄ and A₂ + B₃ [where A₂ is 1,4‐distyrylol‐2,5‐butoxybenzene, B₃ is 1,1,1‐tris‐(p‐tosyloxymethyl)‐propane, and B₄ is pentaerythritol tetra(methyl benzene sulfonate)] approaches, we synthesized two kinds of partially conjugated hyperbranched polymers, hyperbranched polymer with 3 arms (HP1) and hyperbranched polymer with 4 arms (HP2), which had rigid conjugated segments [oligo‐poly(phenylene vinylene)] and flexible, nonconjugated spacers arranged alternately through ether bonds in the skeleton. The conjugated segments were modified by pendant butoxy groups, which imparted the resulting polymers with excellent solubility in common organic solvents and excellent film‐forming abilities. Fourier transform infrared and nuclear magnetic resonance spectroscopy were used to identify the structure of the monomers and polymers. Thermal property investigations showed that two polymers both had good thermal stability with their decomposition temperatures in the range 396–405°C and high glass‐transition temperatures, which are of benefit to the fabrication of high‐performance light‐emitting devices. The photophysical properties were studied, and the relative photoluminescence quantum efficiencies of HP1 and HP2 in dilute chloroform solution amounted to 56.8 and 49.3%, respectively. A brief light‐emitting diode device with a configuration of indium tin oxide/HP1/Ca/Al was fabricated, and its electroluminescence performance was studied. The brightness of the device reached an optimistic maximum of 190 cd/m² at 8.2 V. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Excimer and electromer suppression of tetraphenylsilane‐based blue‐light‐emitting polymers

Excimer and electromer suppression of tetraphenylsilane‐derivative‐based blue polymer light‐emitting devices (PLEDs) was investigated. Tetraphenylsilane with a rigid bulky structure certainly but not completely suppressed excimer formation among polymer‐chain segments. A poor solvent, toluene, resulted in excimer formation in the solid film during the spin‐coating process, which could not be suppressed by the incorporation of a bulky moiety onto the polymer backbone. In addition, electromers or electroplexes formed by the strong interaction between the oxadiazole and diphenyl(4‐tolyl)amine groups could not be prevented by the tetraphenylsilane moiety. The influences of the bulky moiety, bipolar unit, and device fabrication conditions on the suppression of excimers or electromers in PLEDs are discussed in detail. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and properties of polyether with short alternating conjugated and nonconjugated blocks containing oxadiazole units

A polyether, poly[(2,5‐dimethylene‐1,3,4‐oxadiazole)dioxy‐1,4‐phenylene‐1,2‐ethenylene‐1,4‐phenylene‐1,2‐ethenylene‐1,4‐phenylene], based on short alternating conjugated oxadiazole units, has been synthesized, which is a kind of PPV derivative that emits blue light. The resulting polymer is fairly soluble in chloroform. The synthesized polymer shows a UV–visible absorbency maximum wavelength around 310 nm in solution. The photoluminescence maximum wavelength for the resulting polymer appears around 470 nm. The polymer also exhibits good thermal stability up to 300°C under N₂ atmosphere. It is also observed that the onset temperature of thermal decomposition is as high as 355°C. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2682–2686, 2002     

Electroluminescence and photovoltaic properties of poly(p‐phenylene vinylene) derivatives with dendritic pendants

A copolymer of dendronized poly(p‐phenylene vinylene) (PPV), poly{2‐[3′,5′‐bis (2′‐ethylhexyloxy) bnenzyloxy]‐1,4‐phenylene vinylene}‐co‐poly[2‐methoxy‐5‐(2′‐ethylhexyloxy)‐1,4‐phenylene vinylene] (BE‐co‐MEH–PPV), was synthesized with the Gilch route to improve the electroluminescence and photovoltaic properties of the dendronized PPV homopolymer. The polymer was characterized by ultraviolet–visible absorption spectroscopy, photoluminescence spectroscopy, and electrochemical cyclic voltammetry and compared with the homopolymers poly{2‐[3′, 5′‐bis(2‐ethylhexyloxy) benzyloxy‐1,4‐phenylene vinylene} (BE–PPV) and poly[2‐methoxy‐5‐(2′‐ethylhexyloxy)‐1,4‐phenylenevinylene] (MEH–PPV). Polymer light‐emitting diodes based on the polymers with the configuration of indium tin oxide (ITO)/poly(3,4‐ethylene dioxythiophene) : poly(styrene sulfonate) (PEDOT : PSS)/polymer/Ca/Al were fabricated. The electroluminescence efficiency of BE‐co‐MEH–PPV reached 1.64 cd/A, which was much higher than that of BE–PPV (0.68 cd/A) and a little higher than that of MEH–PPV (1.59 cd/A). Photovoltaic properties of the polymer were studied with the device configuration of ITO/PEDOT : PSS/polymer : [6,6J‐phenyl‐C₆₁‐butyric acid methyl ester] (PCBM)/Mg/Al. The power conversion efficiency of the device based on the blend of BE‐co‐MEH–PPV and PCBM with a weight ratio of 1 : 3 reached 1.41% under the illumination of air mass 1.5 (AM1.5) (80 mW/cm²), and this was an improvement in comparison with 0.24% for BE–PPV and 1.32% for MEH–PPV under the same experimental conditions. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis,electroluminescence, and photovoltaic cells of new vinylene‐copolymers with 4‐(anthracene‐10‐yl)‐2,6‐diphenylpyridine segments

Three new soluble vinylene‐copolymers F , C, and P that contain 4‐(anthracene‐10‐yl)‐2,6‐diphenylpyridine as common segment and fluorene, carbazole, or phenylene, respectively, as alternating segment were prepared by Heck coupling. The glass transition temperature was high for F and C (110 and 117°C), whereas was lower than 25°C for P . The polymers were stable up to ～ 300°C. They emitted blue–green light with maximum located at wavelength of 456–550 nm, which was of the order F < C < P . The photoluminescence quantum efficiency in THF solution was ～ 30% for F and P and only 5% for C . All three copolymers were used as active layers for polymer light emitting diodes (PLEDs) and organic photovoltaic cells. The double PLEDs with configuration of indium‐tin oxide (ITO)/poly(ethylenedioxythiophene (PEDOT) : poly(styrenesulfonate)(PSS)/Copolymer F , C , or P /TPBI(1,3,5‐tris(2‐N‐phenylbenzimidazolyl)benzene)/Ca/Al were fabricated. Copolymer P emitted green light with maximum brightness of 28 cd/m² and a current yield of 0.85 cd/A. Organic photovoltaics with the configuration of ITO/PEDOT : PSS/Copolymer and [6,6]‐phenyl‐C61‐butyric acid methyl ester blend (1 : 1) /Ca/Al were also fabricated. Copolymer P showed the highest power conversion efficiency of 0.034%. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Enhanced performance in organic light‐emitting diodes with copolymers containing both tris(8‐hydroxyquinoline) aluminum and 8‐hydroxyquinoline lithium groups

We synthesized novel copolymers containing both tris(8‐hydroxyquinoline) aluminum (Alq₃) and 8‐hydroxyquinoline lithium (Liq) groups as emitting layers for use in conventional two‐layer organic light‐emitting diodes. The network structure and thermal stability of these materials is described. The optical and electroluminescent properties of the copolymers were also studied. The performance optimization of the devices with the copolymers through the variation of the ratio of Alq₃ to Liq is described. A mechanism responsible for the improved electron injection is put forward. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4404–4410, 2006     

Synthesis and characterization of novel two‐component conjugated polythiophenes with 3‐octyl and 3‐isooctylthiophene side chains

With copolymerization functionalization, a novel solution‐processable polymer, poly{(3‐octylthiophene)‐co‐[3‐(2‐ethyl‐1‐hexyl)thiophene]} (P3OTIOT), combining the electrochemical properties of poly(3‐octylthiophene) (P3OT) and poly[3‐(2‐ethyl‐1‐hexyl)thiophene] (P3IOT) was synthesized by the FeCl₃‐oxidative approach. The characterization of the polymers included Fourier transform infrared, ¹H‐NMR, gel permeation chromatography, thermogravimetric analysis (TGA), ultraviolet–visible spectroscopy, and photoluminescence (PL). P3OTIOT had excellent solubility in common organic solvents. Investigations of the optical properties showed that the optical band‐gap energy of P3OTIOT was similar to that of P3OT (2.43 eV) at 2.45 eV and 6% lower than that of P3IOT in CHCl₃ solutions. The bandwidth of the P3OTIOT absorption approached that of P3OT, ranging from 370 to 570 nm, and the emission maximum of P3OTIOT was only 50 nm blueshifted with respect to that of P3OT. However, the PL intensity of P3OTIOT was 7 times higher than that of P3OT. TGA studies showed that P3OTIOT had very good thermal stability, losing 5% of its weight on heating to 300°C. It is suggested that P3OTIOT has low band‐gap energy, a high PL quantum yield, and processability. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1169–1175, 2007     

Synthesis and photoluminescent properties of poly(aryl ether)s containing alternate emitting and electron‐transporting moieties

A new diphenylbutadiene‐containing bisphenol was successfully synthesized from benzylideneaniline and 4‐propenylanisole via an anil synthetic method. A series of copoly(arylene ether)s consisting of an alternate isolated blue chromophore (diphenylbutadiene) and an electron‐transporting moiety (1,3,4‐oxadiazole) was synthesized and characterized. High molecular weight copoly(arylene ether)s with an inherent viscosity of >0.5 dL/g were prepared by the nucleophilic displacement reaction of oxadiazole‐activated bis‐fluorocompounds with bisphenols. Introduction of ether linkages into the copolymers led to an enhanced solubility in organic solvents such as N,N‐dimethylacetamide (DMAc) and N‐methyl‐2‐pyrrolidinone (NMP). The resulting copolymers can be cast into tough and transparent films. The copolymers were amorphous in structure with high glass transition temperatures ranging from 182.29 to 194.50°C. They also exhibited good thermal stability with the maximum decomposition temperatures higher than 500°C in nitrogen. The absorption peaks of these copolymers in thin films varied from 375 to 391 nm, while the photoluminescent peaks varied from 410 to 433 nm. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1645–1651, 2003     

Synthesis and characterization of photo‐crosslinkable polyfluorene with acrylate side‐chains

A photo‐crosslinkable polymer, poly[2,7‐(9,9‐dioctylfluorene)‐co‐2,7‐(9‐hexyl‐9‐(2‐acrylate ethyl)‐9H‐fluorene)] (P3), was synthesized and the photo‐crosslinkable acrylate groups were introduced into the side‐chains of the polyfluorene derivative after its polymerization. This method avoids the possible crosslinkage of the crosslinkable groups on the monomers during polymerization in the traditional synthesis route by the polymerization of the monomers with the crosslinkable side‐chains. The soluble and processable polymer P3 could be crosslinked via the acrylate groups in its side‐chains upon exposure to UV light in nitrogen atmosphere. The crosslinking was confirmed by IR spectroscopy: the IR peak of C?C bond at 1635 cm^?1 decreased and that of the vinyl C? H bond at 742 cm^?1 disappeared after the UV exposure. The absorption spectra of P3 remain unchanged after crosslinking, but a longer wavelength emission at 517 nm appeared in the photoluminescent and electroluminescent spectra of the crosslinked P3, which could be attributed to the formation of keto defects during the photo crosslinking. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2336–2342, 2006     

Synthesis and characterization of new blue‐photoluminescent copolymer derived from bisphenol A

A new copolymer with short alternating conjugated and nonconjugated blocks, derived from bisphenol A (BPAEt₂‐PPV) containing separated phenylenevinylene (PV) units has been synthesized by Wittig condensation. The copolymer is fully soluble in common organic solvents and has a number‐average molecular weight of 3200 with a polydispersity index of 1.53. The structure of the polymer was confirmed by ¹H NMR, ¹³C NMR, FTIR and Raman spectroscopic analysis. Thermogravimetric analysis and differential scanning calorimetry indicate that BPAEt₂‐PPV is stable up to 400°C in air and displays a glass transition temperature of 107°C. The fluorescence spectrum of the polymer film shows an emission in the blue region (428, 456, and 488 nm). The band‐gap energy, estimated from the edge absorption of the film, is about 2.9 eV. A single‐layer diode device of the configuration ITO/BPAEt₂‐PPV/Al has been fabricated and has a relatively low turn‐on voltage of 3.7 V. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Novel copolymers for electroluminescent devices

Two novel luminescent block copolymers (CE–PPV and CE–DMPPV), containing alternating distyrylbenzene [poly(phenylene vinylene) model oligomer] as light‐emitting units and crown‐ether segments as ionic conductive and spacer units were synthesized by use of a Wittig reaction between the dialdehyde monomer and 1,4‐xylylene‐bis(triphenylphosphonium bromide) or 1,4‐bis(triphenylphosphoniomethyl)‐2,5‐dimethoxybenzene dichloride. The synthesized polymers were characterized with FTIR, ¹H‐NMR, UV–Vis, differential scanning calorimetry, and gel permeation chromatography. The number‐average molecular weights were 6896 with a polydispersity index of 1.75 for CE–PPV, and 9301 with a polydispersity index of 2.474 for CE–DMPPV, respectively. The decomposition temperatures and the glass‐transition temperatures were in the range of 395–411°C and 75–77°C, respectively. The electrochemical properties of the copolymers were evaluated and the highest occupied molecular orbital and the lowest unoccupied molecular orbit energy levels of the copolymers were estimated by cyclic voltammetry. Efficient light‐emitting diodes were successfully fabricated. The synthesis, characterization, and electroluminescent properties of the polymers are reported in this study. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3316–3321, 2002     

Origin of the methylene bonds in poly[2‐methoxy‐5‐(2′‐ethyl‐hexyloxy)‐1,4‐phenylenevinylene] prepared according to Gilch's method: novel applications

Impurities containing methylene bridges between 2‐((2′‐ethylhexyl)oxy)‐5‐methoxy‐benzene molecules are inevitably formed during the synthesis of 1,4‐bis(chloromethyl)‐2‐((2′‐ethylhexyl)oxy)‐5‐methoxy‐benzene, the monomer used in the preparation of poly[2‐methoxy‐5‐(2′‐ethyl‐hexyloxy)‐1,4‐phenylenevinylene] (MEH‐PPV), but they can be removed by double recrystallization of the monomer prior to polymerization. When impurities containing methylene bridges participate in a Gilch polymerization, the methylene bonds formed in the main chains are prone to break at 200 °C, that is, at least 150 °C below the major degradation temperature of defect‐free MEH‐PPV. Interestingly, the thermal treatment used to break the methylene bonds present reduces the chain aggregation of MEH‐PPV during film formation and induces its blends with poly(2,3‐diphenyl‐5‐octyl‐p‐phenylene‐vinylene) (DPO‐PPV) to form a morphology similar to that of block copolymers. Both significantly enhance the luminescence properties. Copyright © 2006 Society of Chemical Industry     

Synthesis and properties of a soluble conjugated polymer,poly(2‐methoxy‐5‐N‐butoxy‐p‐phenylene vinylene)

The synthesis of poly(2‐methoxy‐5‐n‐butoxy‐p‐phenylene vinylene) (MBPPV) via a dehydrochlorination of 2‐methoxy‐5‐n‐butoxy‐α,α′‐dichloro‐p‐xylene is described. The soluble polymer was characterized by elemental analysis, Fourier transform infrared (FTIR), ¹H nuclear magnetic resonance (NMR), and UV‐visible spectroscopy. The energy gap (Eg) of the polymer was 2.53 eV determined by cyclic voltammogram. Light‐emitting diode (LED) and light‐emitting electrochemical cell (LEC) with the polymer were fabricated. The LED displayed unipolar I‐V dependence with the turn‐on voltage at 4.2 V. I‐V curve of the LEC with poly(ethylene oxide) (PEO, Mw 2 × 10⁴) displayed mirror symmetry with the turn‐on voltage at 2.7 V, but to the device with PEO (Mw 5 × 10⁶) no mirror symmetry was observed, the turn‐on voltages at +2.7 V, −11.5 V. The emission maximum of the polymer in chloroform was at λ = 550 nm, whereas the emission maxima of the LED at 5.2 V and the LEC at 4.8 V were at λ = 566, 569 nm, respectively. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2180–2185, 2000     

Novel 1,4‐diketo‐3,6‐diphenyl pyrrolo[3,4‐c]pyrrole (DPP)‐based copolymers with large Stokes shift

Two novel alternating π‐conjugated copolymers, named PDPPDOPV and PDPPDOPE, constituted of 1,4‐diketo‐3,6‐diphenyl pyrrolo[3,4‐c]pyrrole (DPP) with 2,5‐dioctyloxy‐1,4‐phenylenevinylene (DOPV) or 2,5‐dioctyloxy‐1,4‐phenyleneethynylene (DOPE), respectively, were synthesized and characterized by UV‐vis, FT‐IR, and photoluminescence spectroscopy. They are dark red solid readily soluble in various common organic solvents including THF and chloroform. The UV‐vis absorption spectra of the polymers show strong absorption bands, which correspond to the π‐π* transition of π‐conjugated segments. Photoluminescence (PL) spectra show that both polymer films and solution have large Stokes shifts. From their fluorescence behavior, Stokes shifts of 173 nm and 199 nm are derived for the films of PDPPDOPV and PDPPDOPE, respectively, which are the largest two values ever reported for DPP‐containing polymers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis,characterization, and photophysics of a novel conjugated polymer with 1,3,4‐oxadiazole,carbazole, and naphthalene units

A polymer containing 1,3,4‐oxadiazole and carbazole units in the main chain and naphthalene moieties as side groups (P‐OCN) was synthesized by the Wittig reaction of [2,5‐bis(3‐tolylene)1′,3′,4‐oxadiazole]‐9‐(α‐naphthyl)‐carbazole polymer (P‐OCN). The optical properties were investigated with ultraviolet–visible absorption and fluorescence emission spectra. The results showed that the luminescence quantum yield of P‐OCN was 0.673 in chloroform, and it emitted blue and blue‐green light with a band gap of 3.49 eV estimated from the onset absorption. Thermogravimetric analysis and differential scanning calorimetry showed that the polymer exhibited good thermal stability up to 354°C with a glass‐transition temperature higher than 110°C. To investigate the donating and accepting capacities of P‐OCN, the fluorescent quenching technique was used to determinate the interactions between the polymer and the electron donor and electron acceptor. The results showed that the light emission could be quenched by both the electron donor (N,N‐dimethylaniline) and electron acceptor (dimethylterephthalate). Furthermore, the interaction between P‐OCN and fullerene was also studied with fluorescent quenching, and the processes followed the Stern–Volmer equation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis,characterization, and photophysical properties of novel poly(p‐phenylene vinylene) derivatives with conjugated thiophene as side chains

Two novel poly(p‐phenylene vinylene) (PPV) derivatives with conjugated thiophene side chains, P1 and P2, were synthesized by Wittig‐Horner reaction. The resulting polymers were characterized by ¹H‐NMR, FTIR, GPC, DSC, TGA, UV–Vis absorption spectroscopy and cyclic voltammetry (CV). The polymers exhibited good thermal stability and film‐forming ability. The absorption spectra of P1 and P2 showed broader absorption band from 300 to 580 nm compared with poly[(p‐phenylene vinylene)‐alt‐(2‐methoxy‐5‐octyloxy‐p‐phenylene vinylene)] (P3) without conjugated thiophene side chains. Cyclic voltammograms displayed that the bandgap was reduced effectively by attaching conjugated thiophene side chains. This kind of polymer appears to be interesting candidates for solar‐cell applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis,structural and spectral properties of an ionic polyacetylene: Poly[N‐(5‐nitro‐2‐furanmethylene)‐2‐ethynylpyridinium bromide]

A new ionic polyacetylene was prepared by the activation polymerization of 2‐ethynylpyridine with 2‐(bromomethyl)‐5‐nitrofuran in high yield without any additional initiator or catalyst. This polymerization proceeded well in a homogeneous manner to give a high yield of the polymer (92%). The activated acetylenic triple bond of N‐(5‐nitro‐2‐furanmethylene)‐2‐ethynylpyridinium bromide, formed in the first quaternerization process, was found to be susceptible to linear polymerization. This polymer was completely soluble in such polar organic solvents as dimethylformamide, dimethyl sulfoxide, and N,N‐dimethylacetamide. The inherent viscosities of the resulting polymers were in the range 0.12–0.19 dL/g, and X‐ray diffraction analysis data indicated that this polymer was mostly amorphous. The polymer structure was characterized by various instrumental methods to have a polyacetylene backbone structure with the designed substituent. The photoluminescence peak was observed at 593 nm; this corresponded to a photon energy of 2.09 eV. The polymer exhibited irreversible electrochemical behaviors between the doping and undoping peaks. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011