Dependence of optical properties on the preparation methods of poly[(9,9′‐dialkylfluorene‐2,7‐diyl)‐alt‐(1,3,4‐oxadiazole‐2,5‐diyl)]

A blue‐light‐emissive fluorene‐based polyoxadiazole, an n‐type polyfluorene derivative, was synthesized by both one‐step and two‐step methods. Directly polymerized poly[(9,9′‐didodecylfluorene‐2,7‐diyl)‐alt‐(1,3,4‐oxadiazole‐2,5‐diyl)] (PFOx‐DP) exhibited a higher molecular weight and a more efficient photoluminescence quantum yield than poly[(9,9′‐didodecylfluorene‐2,7‐diyl)‐alt‐(1,3,4‐oxadiazole‐2,5‐diyl)] (PFOx) prepared via a polyhydrazide precursor, poly[9,9′‐didodecylfluorene‐2,7‐(2,5‐dihydrazide‐ 1,3,4‐oxadiazole). Both polymers, differently prepared, showed similar photoluminescent properties in 1,2‐dichloroethane. However, in a film state, the influence of the interchain interactions on the photoluminescence of PFOx with the lower molecular weight was larger than on the photoluminescence of PFOx‐DP. The electron‐deficient property of an oxadiazole group in the polymer backbone resulted in low‐lying highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels of ?6.29 and ?3.26eV, respectively, of the polymer suitable for electron‐transport/hole‐blocking layers and emissive layers in multilayer electroluminescence devices. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3112–3118, 2004     

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     

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     

Effect of interchain interaction on optical properties of poly(p‐phenylene vinylene) derivative containing oxadiazole in backbone

We have investigated the optical properties of poly [2‐methoxy‐5‐(2‐ethylhexyloxy)‐1,4‐phenylene vinylene] containing oxadiazole in backbone (MEH‐OPPV) in dilute tetrahydrofuran solution and solid solution films. There is a large dihedral angle between the two adjacent monomer units in MEH‐OPPV, which restrains interchain interactions and destroys the conjugation of the polymer to result in blue shifted absorption and emission spectra. The red shifted photoluminescence (PL) peak is continuously changed in the solid solution films with increasing the concentration of MEH‐OPPV. Comparison with the dilute solution, an obvious shoulder peak at 465 nm is found in the UV–vis absorption and PL excitation (PLE) spectra of the MEH‐OPPV film. The intensity of the PLE shoulder at 465 nm is increased with the concentration of MEH‐OPPV in the solid solution films, which is connected with the aggregation of the MEH‐OPPV chains. The interchain interactions are restrained and the π‐stack aggregates of the polymer chains can not form in the MEH‐OPPV due to the large dihedral angle, and then the interchain species are effectively suppressed in the MEH‐OPPV films. © 2011 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     

Electrochemical behaviors of polyaniline–poly(styrene‐sulfonic acid) complexes and related films

This research focuses on the syntheses of polyaniline with poly(styrenesulfonic acid) and their electrochemical behavior, including absorbance behavior and electrochemical response time of polyaniline‐poly(styrenesulfonic acid) [PANI–PSSA]. The complexes PANI–PSSA were prepared by electrochemical polymerization of monomer (aniline) with PSSA, using indium‐tin oxide (ITO) as working electrode in 1M HCl solution. Polyaniline (PANI), poly(o‐phenetidine)–poly(styrenesulfonic acid) [POP–PSSA], and poly(2‐ethylaniline)–poly(styrenesulfonic acid) [P2E‐PSSA] also were prepared by electrochemical polymerization and to be the reference samples. The products were characterized by IR, VIS, EPR, water solubility, elemental analysis, conductivity, SEM, and TEM. IR spectral studies shows that the structure of PANI–PSSA complexes is similar to that of polyaniline. EPR and visible spectra indicate the formation of polarons. The morphology of the blend were investigated by SEM and TEM, which indicate the conducting component and electrically conductive property of the polymer complexes. Elemental analysis results show that PANI–PSSA has a nitrogen to sulfur ratio (N/S) of 38%, lower than that for POP–PSSA (52%) and P2E–PSSA (41%). Conductivity of the complexes are around 10^?2 S/cm, solubility of PANI–PSSA in water is 3.1 g/L. The UV‐Vis. absorbance spectra of the hybrid organic/inorganic complementary electro‐chromic device (ECD), comprising a polyaniline–poly(styrenesulfonic acid) [PANI–PSSA] complexes and tungsten oxide (WO₃) thin film coupled in combination with a polymer electrolyte poly(2‐acrylamido‐2‐methyl‐propane‐sulfonic acid) [PAMPSA]. PANI–PSSA microstructure surface images have been studied by AFM. By applying a potential of ～3.0 V across the two external ITO contacts, we are able to modulate the light absorption also in the UV‐Vis region (200–900 nm) wavelength region. For example, the absorption changes from 1.20 to 0.6 at 720 nm. The complexes PANI–PSSA, POP–PSSA, and P2E–PSSA were prepared by electrochemical polymerization of monomer (aniline, o‐phenetidine, or 2‐ethylaniline) with poly(styrenesulfonic acid), using ITO as working electrode in 1M HCl solution, respectively. UV‐Vis spectra measurements shows the evidences for the dopped polyaniline system to be a highly electrochemical response time, recorded at the temperature 298 K, and the results were further analyzed on the basis of the color‐ discolor model, which is a typical of protontation systems. Under the reaction time (3 s) and monomer (aniline, o‐phenetidine, 2‐ethylaniline) concentration (0.6M) with PSSA (0.15M), the best electrochemical color and discolor time of the PANI–PSSA is slower than POP–PSSA complexes (125/125 ms; thickness, 3.00 μm) and P2E–PSSA complexes. Under the same thickness (10 μm), the best electrochemical color and discolor time of the PANI–PSSA complexes is 1500/750 ms, that is much slower than P2E–PSSA complexes (750/500 ms) and POP–PSSA complexes (500/250 ms). In film growing rate, the PANI–PSSA complexes (0.54 μm/s) are slower than P2E–PSSA complexes (0.79 μm/s) and POP–PSSA complexes (1.00 μm/s), it can be attributed to the substituted polyaniline that presence of electro‐donating (? OC₂H₅ or ? C₂H₅₎ group present in aniline monomer. The EPR spectra of the samples were recorded both at 298 K and 77 K, and were further analyzed on the basis of the polaron–bipolaron model. The narrower line‐width of the substituted polyaniline complexes arises due to polarons; i.e., it is proposed that charge transport take place through both polarons and bipolarons, compared to their salts can be attributed to the lower degree of structural disorder, the oxygen absorption on the polymeric molecular complexes, and due to presence of electro‐donating (? OC₂H₅ or ? C₂H₅) group present in aniline monomer. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100:4023–4044, 2006     

Measurement of the electrochemical response time and electron paramagnetic resonance behavior of poly(o‐phenetidine)–poly(styrene sulfonic acid) and poly(2‐ethylaniline)–poly(styrene sulfonic acid) complexes

Two studies were mainly focused on the measurement of electrochemical response time and the electron paramagnetic resonance (EPR) of the substituted polyaniline (PANI) complexes poly(o‐phenetidine) (POP)–poly(styrene sulfonic acid) (PSSA) and poly(2‐ethylaniline) (P2E)–PSSA, which were prepared by the electrochemical polymerization of the monomer (o‐phenetidine or 2‐ethylaniline) with PSSA, with indium tin oxide (ITO) as a working electrode in a 1M HCl solution. Ultraviolet–visible spectra measurements showed evidence for the doped substituted PANI system to have a highly electrochemical response time recorded at a temperature of 298 K, and the results were further analyzed on the basis of the color–discolor model, which is typical of protonation systems. At the reaction time (3 s) and monomer concentration (0.6M) with PSSA (0.15 μ), the best electrochemical color/discolor time of the POP–PSSA complexes was 125/125 ms (thickness = 3.00 μm), which was faster than that of the P2E–PSSA complexes. At the same thickness (10 μm), the best electrochemical color/discolor time of the POP–PSSA complexes was 500/250 ms, which was faster than the P2E–PSSA complexes (750/500 ms). With regard to film growth rate, the POP–PSSA complexes (1.0 μm/s) were faster than the P2E–PSSA complexes (0.79 μm/s); this was attributed to the substituted PANI having a steric effect and to good reactivity by the ethoxy group (? OC₂H₅) in the molecules. The EPR spectra of the two samples were recorded both at 298 and 77 K and were further analyzed on the basis of the polaron–bipolaron model. The narrower line width of the substituted PANI complexes arose due to polarons; that is, we propose that charge transport took place through both polarons and bipolarons. Compared to their salts, this could be attributed to the lower degree of structural disorder, the oxygen absorption on the molecules, and the steric effect by the side chain group. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1211–1221, 2005     

Preparation and characterization of thin films of the poly(p‐phenylene vinylene) semiconducting polymer

Conjugated polymers have been the subject of many studies because of their widespread applications in electronic and optoelectronic devices. Poly(p‐phenylene vinylene) is a leading semiconducting polymer in optical applications. This work is focused on the development of thin films of poly(p‐phenylene vinylene) by spin coating and their characterization with Fourier transform infrared spectroscopy, X‐ray diffraction, and scanning electron microscopy to understand their changes. An empirical model has been developed to show the effect of the variables—the spin speed, polymer concentration, and spin time—on the film thickness. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Polymeric coatings for photostability enhancement of poly(p‐phenylene vinylene) derivative films

Poly(p‐phenylene vinylene) (PPV) derivatives are an important class of conjugated polymers, known for their applications as electroluminescent materials for light‐emitting devices and sensors. These derivatives are highly susceptible to photodegradation by the combined action of oxygen and light. Here, the use of various commercial polymers as protective coatings against the photodegradation of PPV derivatives was explored. Cast films of two similar PPV derivatives, poly[(2‐methoxy‐5‐n‐hexyloxy)‐p‐phenylene vinylene] and poly[2‐methoxy‐5‐(2‐ethylhexyloxy)‐p‐phenylene vinylene], were submitted to photodegradation by exposure to white light under atmospheric conditions in order to verify if the type of side chain (linear or branched) had an effect on the photodegradation. No significant differences in the photodegradation behaviour between the two polymers were noticed. The following commercial polymers were tested as protective coatings for the PPV derivative cast films: 99 and 80% hydrolysed poly(vinyl alcohol) (PVA) and starch. The best results were achieved using coatings of 99% hydrolysed PVA, which increased about 700 times the time necessary for complete degradation of the PPV derivative films. The results show the effectiveness of this coating in minimizing and, possibly, controlling the effects of the photodegradation of PPV derivative films, which can be useful in many applications, e.g. oxygen sensors. Copyright © 2009 Society of Chemical Industry     

Controlling the photoluminescence of water‐soluble conjugated poly[2‐(3‐thienyl)ethyloxy‐4‐butylsulfonate)] for biosensor applications

The photoluminescence of poly[2‐(3‐thienyl)ethyloxy‐4‐butylsulfonate)] (PTE‐BS) in aqueous solution increases threefold on addition of the surfactant tetrabutylammonium perchlorate (TBA). Furthermore, the luminescence of the PTE‐BS/TBA system is reduced by more than five times by the addition of small amounts of the cationic electron acceptor methyl viologen (MV²⁺). The Stern–Volmer constant K_SV = 1.4 × 10⁴ L mol^?1 for the quenching of the polymer–surfactant complex by MV²⁺ is approximately 60 times smaller than the K_SV = 8.4 × 10⁵ L mol^?1 obtained in water polymer solutions without surfactant. Thus, the luminescence of PTE‐BS in aqueous solution can be modulated by complexing the polymer either with a surfactant or with a quencher. In this contribution we show that the surfactant/quencher tuning effect found in polymers of the phenylenevinylene family, such as poly(2,5‐methoxy‐propyloxysulfonate phenylenevinylene), also appears in polymers of the thiophene family such as PTE‐BS. Copyright © 2007 Society of Chemical Industry     

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     

Composites of poly(2‐chloroaniline) and poly(o‐toluidine) with pumice and their application in the removal of chromium(VI) ions from aqueous solutions

Poly(2‐chloroaniline) (P2ClAn)/pumice (Pmc) and poly(o‐toluidine) (POT)/Pmc composites were synthesized via the chemical oxidative polymerization of 2‐chloroaniline and o‐toluidine in the presence of a dispersion of Pmc powders in water solvent with an (NH₄)₂S₂O₈ oxidant. The composites were characterized with Fourier transform infrared (FTIR) spectroscopy, thermo‐gravimetric/differential thermal analysis (TG‐DTA), and scanning electron microscopy devices. The presence of P2ClAn and POT in the structure of the composites was confirmed by FTIR. Theresults of analysis show strong interactions between the homopolymers and Pmc. The applicability of the P2ClAn/Pmc and POT/Pmc composites were investigated for the removal of Cr(VI) ions in water. Batch adsorption experiments were carried out as a function of pH, initial concentration, time, adsorbent dosage, and temperature. The batch sorption kinetics were tested, and the applicability of the Langmuir and Freundlich adsorption isotherms for this system was tested at 20 ± 1°C. An initial pH of 3.0 was most favorable for Cr(VI) removal by all adsorbents. The adsorption capacities obtained were 0.187 and 4.959 mmol/g of adsorbent for POT/Pmc and P2ClAn/Pmc from the Freundlich and Langmuir adsorption isotherms, respectively. © 2007 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     

Chemical preparation of conducting polyfuran/poly(2‐chloroaniline) composites and their properties: A comparison of their components,polyfuran and poly(2‐chloroaniline)

Conductive homopolymers and composites of poly(2‐chloroaniline) (P2ClAn) and polyfuran (PFu) were synthesized chemically in hydrous and anhydrous media, and their properties were investigated. The polymers and composites were characterized by Fourier infrared spectroscopy, ultraviolet‐visible absorption spectroscopy, thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy, magnetic susceptibility, and conductivity measurements. It was found that the PFu/P2ClAn composite is thermally more stable than both the P2ClAn/PFu composite and the homopolymers. It was determined from Gouy scale measurements that conducting mechanisms of homopolymers and composites are polaron and bipolaron in nature. It was observed that the conductivity and magnetic susceptibility values changed with a changing amount of the guest polymer in the prepared composites. The conductivity (3.21 × 10^?2 S/cm) of the P2ClAn/PFu (55.8% m/m) composite was found to be higher than the conductivities of both homopolymers (σ_PFu = 1.44 × 10^?5 S/cm; σ_P2ClAn = 1.32 × 10^?3 S/cm). It was determined that the composites synthesized had different conductivities and morphological and thermal properties from changing synthesis order. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2924–2931, 2003     

Blue light‐emitting poly(p‐phenylenevinylene) derivative with oxadiazole and carbazole pendant groups

A blue light‐emitting statistical poly(p‐phenylenevinylene) (PPV) copolymer with hole‐transporting carbazole and electron‐transporting oxadiazole pendant groups attached to the kinked m‐terphenyl unit was prepared by Heck coupling between 1,4‐divinylbenzene and dibromides. The latter were synthesized through pyrylium salts. The polymer had optical band gap of 2.89 eV and emission maximum at 446 nm in THF solution and 434 nm in thin film. It showed a pure blue emission with no aggregates or excimers formed even in solid state because of the long and bulky pendant groups. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3842–3849, 2006     

New fluorene–pyrazino[2,3‐g]quinoxaline‐conjugated copolymers: Synthesis,optoelectronic properties,and electroluminescence characteristics

New donor–acceptor conjugated copolymers called poly}2,7‐(9,9′‐dihexylfluorene)‐co‐5,10‐[pyrazino(2,3‐g)quinoxaline]{s or PFPQs [where F represents the 2,7‐(9,9′‐dihexylfluorene) moiety and PQ represents the 5,10‐(pyrazino[2,3‐g]quinoxaline) moiety], synthesized by the palladium‐catalyzed Suzuki coupling reaction, are reported. The PQ contents in the PFPQ copolymers were 0.3, 1, 5, and 50 mol %, and the resulting copolymers were named PFPQ0.3, PFPQ01, PFPQ05, and PFPQ50, respectively. Absorption spectra showed a progressive redshift as the PQ acceptor content increased. The relatively small optical band gap of 2.08 eV for PFPQ50 suggested strong intramolecular charge transfer (ICT) between the F and PQ moieties. The photoluminescence emission peaks of the PFPQ copolymer films also exhibited a large redshift with enhanced PQ contents, ranging from 551 nm for PFPQ0.3 to 592 nm for PFPQ50. However, the PFPQ copolymer based electroluminescence (EL) devices showed poor device performances probably due to the strong confinement of the electrons in the PQ moiety or significant ICT. This problem was resolved with a binary blend of poly[2,7‐(9,9‐dihexylfluorene)] (PF) and PFPQ with a volume ratio of 95/5 (BPQ05). Multiple emission peaks were observed at 421, 444, 480, 516, and 567 nm in the BPQ05‐based EL devices because the low PQ content led to incomplete energy transfer. The Commission Internationale de L'Eclairage 1931 coordinates of the BPQ05‐based EL device were (0.31, 0.32), which were very close to the standard white emission of (0.33, 0.33). Furthermore, the maximum luminescence intensity and luminescence yield were 524 cd/m² and 0.33 cd/A, respectively. This study suggested that a pure white light emission was achieved with the PFPQ copolymers or PF/PFPQ blends through the control of the energy transfer between F and PQ. Such PFPQ copolymers or PF/PFPQ blends would be interesting for electronic and optoelectronic devices. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Thermosensitive poly(n‐isopropylacrylamide) hydrogels bonded on cellulose supports

A two‐step initiation and polymerization process was developed for the preparation of two series of hydrogel–cellulose composites with distinctively different morphologies and swelling behaviors. Hydroentangled cotton cellulose fibers were optimally initiated in 20 mM aqueous ammonium cerium(IV) nitrate for 15 min and then polymerized in aqueous solutions of N‐isopropylacrylamide (NIPAAm) monomer and N,N′‐methylene bisacrylamide (BisA) crosslinker. The extents of hydrogels on the cellulose solids could be controlled by variations in the concentrations of the monomer and crosslinker as well as the NIPAAm/BisA solution‐to‐solid ratios. The two series of hydrogel–cellulose composites formed were hydrogel‐covered/filled cellulose (I) and cellulose‐reinforced hydrogel (II) composites. Series I composites were synthesized with NIPAAm/BisA solutions below the liquid saturation level of the cellulose; this led to pore structures (size and porosity) that depended on both the extent and swelling of the grafted hydrogels. Series II composites were polymerized in the presence of excessive NIPAAm/BisA solutions to produce cellulose solids completely encapsulated in the hydrogels. All the cellulose‐supported hydrogels exhibited lower extents of phase transition over a wider temperature range (28–40°C) than the free poly(N‐isopropylacrylamide) hydrogels (32°C). These findings demonstrate that hydrogels can be used to control the pore structure of cellulose and can be supported with cellulose fibers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 999–1006, 2003     

Effect of microstructure on the dielectric properties of poly(vinyl alcohol)–poly(3,4‐ethylenedioxythiophene) doped with poly(styrenesulfonate) composite films

Poly(3,4‐ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT–PSS) was blended with poly(vinyl alcohol) (PVA) to form 0, 10, 20, 30, 40, and 50 vol % PEDOT–PSS/PVA solutions, and their freestanding films were prepared with a simple and cost‐effective solution casting technique at 27 °C in the absence of additives. Field emission scanning electron microscopy images revealed changes in the cocontinuous network to a rodlike morphology in the composite films from 10 to 50 vol % PEDOT–PSS/PVA. The alternating‐current conductivity was found to obey Jonscher's power law. The obtained values of the dielectric constant at 27 °C were relatively high, and a maximum value of 6.7 × 10⁴ at 100 Hz for 40 vol % PEDOT–PSS'/PVA was observed. The dielectric loss attained a maximum value of about 10⁶ at 100 Hz for 40 vol % PEDOT–PSS/PVA. However, a decrease in the dielectric parameters was observed at 50 vol % PEDOT–PSS/PVA because of locally induced strain in the microstructure. The variations in polarization with respect to the applied electric field (P–E) were determined for 50, 100, and 500 Hz at 500 V for the freestanding composite films of lower concentrations up to 20 vol % PEDOT–PSS/PVA. In summary, the dielectric and P–E measurements confirmed that the electrical characteristics changed in accordance to the contribution from both resistive and capacitive sites in the PEDOT–PSS/PVA composites. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45079.     

Interfacially initiated microemulsion copolymerization: One‐stage preparation of poly(n‐butyl methacrylate)–poly(N‐vinyl pyrrolidone) core–shell nanoparticles

Interfacially initiated microemulsion copolymerizations of n‐butyl methacrylate (BMA) and N‐vinyl pyrrolidone (NVP) by the redox initiation couple of benzoyl peroxide and ferrous sulfate were carried out with Tween 80 and n‐butanol as the surfactant and cosurfactant, respectively. Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy were recorded to analyze the chemical composition of the latex particles. Transmission electron microscopy was used to observe the particle morphology and dynamic light scattering to determine the particle size. The results demonstrated that interfacially initiated microemulsion polymerization prompted the copolymerization of the water‐soluble NVP monomer with the oil‐soluble BMA monomer to form core–shell nanoparticles. The influence of the surfactant concentration, BMA amount, and temperature on the particle size and polymerization rate was investigated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3751–3757, 2006     

n‐Butyl acrylate based latex interpenetrating polymer networks used as processing modifiers and impact modifiers of poly(vinyl chloride)

A latex interpenetrating polymer network (LIPN), consisting of poly(n‐butyl acrylate), poly(n‐butyl acrylate‐co‐ethylhexyl acrylate), and poly(methyl methacrylate‐co‐ethyl acrylate) and labeled PBEM, with 1,4‐butanediol diacrylate as a crosslinking agent was synthesized by three‐stage emulsion polymerization. The initial poly(n‐butyl acrylate) latex was agglomerated by a polymer latex containing an acrylic acid residue and then was encapsulated by poly(n‐butyl acrylate‐co‐ethylhexyl acrylate) and poly(methyl methacrylate‐co‐ethyl acrylate). A polyblend of poly(vinyl chloride) (PVC) and PBEM was prepared through the blending of PVC and PBEM. The morphology and properties of the polyblend were studied. The experimental results showed that the processability and impact resistance of PVC could be enhanced considerably by the blending of 6–10 phr PBEM. This three‐stage LIPN PBEM is a promising modifier for manufacturing rigid PVC. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1168–1173, 2004