烷基聚噻吩和聚醋酸乙烯酯梯度构造膜的自组装过程及导电性能研究

以烷基聚噻吩（PAT-6）和聚醋酸乙烯酯（PVAc）共混液为原料通过浇注方式制膜。通过控制干躁速度,在膜厚度方向可自组装形成梯度膜。沿膜厚方向对导电性进行检测,发现导电性随着PAT-6组分的增加而增强。     

Nanostructured poly(3-hexylthiophene-2,5-diyl) films with tunable dimensions through self-assembly with polystyrene

Poly(3-hexylthiophene-2,5-diyl) is among the most widely used conjugated polymers for opto-electronic applications. To enhance its properties, researchers have attempted to nanostructure this polymer using various processes including breath figure arrays, nanolithography and elaborated organic synthesis. We here demonstrate a simple process to nanostructure the conjugated polymer using self-assembly with polystyrene and selective removal of one of the phases. The influence of the molecular weight of each polymer on the thin film morphology was systematically studied by atomic force microscopy. Using this approach, we observe two types of nanostructure, namely, nanoporous and nanoisland structures, of which the dimensions can be tuned by modifying the molecular weight of each polymer in the blend. This simple process introduces a cost-effective alternative to produce thin films of conjugated polymer with average nano-features from 100 nm up to 500 nm which could be used in a wide range of applications.     

Synthesis of hydroxyphenylglycine-derived novel poly(silylenevinylenephenyleneethynylene)s

The hydrosilylation polymerization of d-(−)-p-hydroxyphenylglycine-derived diethynyl monomers 1p and 1m with dihydrosilanes Si1 and Si2 was carried out using RhI(PPh₃)₃ as a catalyst to give optically active novel poly(silylenevinylenephenyleneethynylene)s [(E)-poly(1p-Si1), (E)-poly(1p-Si2), (E)-poly(1m-Si1), (E)-poly(1m-Si2), and (Z)-poly(1p-Si1)] with number-average molecular weights ranging from 2800 to 17,000 in 41-92% yields. Polymers having (E)- and (Z)-olefin moieties were obtained, wherein the (E)-/(Z)-ratios depended on the reaction conditions. The UV-vis absorption edge of (E)-poly(1p-Si1) was positioned at a wavelength longer than that of (Z)-poly(1p-Si1), indicating that (E)-vinylene-linkage extends the conjugation more largely than the (Z)-counterpart. This was also confirmed by fluorescence spectroscopy. Alkaline hydrolysis of ester moieties of these polymers gave the corresponding polymers having carboxy groups. The (E)-polymers showed different solubility in hydrophobic solvents before and after hydrolysis, but the non-hydrolyzed and hydrolyzed (Z)-polymers exhibited the same solubility.     

Thermoreversible gelation of poly(vinylidene fluoride)/poly(methyl acrylate) blends in diethyl azelate: a thermodynamic investigation

The thermodynamic behaviour of poly(vinylidene fluoride) (PVF₂)/poly(methyl acrylate) (PMA) blend gels in diethyl azelate (DEAZ) was studied by differential scanning calorimetry at three different blend compositions (x (weight fraction of PVF₂ in the blend) = 0.75, 0.5 and 0.25). Transmission electron microscopy together with optical microscopy indicate the presence of fibrillar network morphology in the gels. The quasi‐binary phase diagrams drawn from both the heating and cooling processes are almost similar, with a hysteresis of 50–60 °C. The possibility of polymer–solvent compound formation in the blend gels have been explored from the composition dependency of enthalpy of gel fusion and enthalpy of gel formation data. Extending the procedure of the pure PVF₂/DEAZ gel systems to blend gels, it has been surmised that polymer–solvent compound formation also occurs in blend gels, but the stoichiometry of the complexes varies with blend composition. The shapes of the quasi‐binary phase diagrams of the blend gels are different in some cases from that of pure PVF₂/DEAZ, gel indicating that the polymer–solvent compounds are incongruent or singular type depending on the blend compositions. A possible explanation for this behaviour has been offered from entropic and enthalpic viewpoints. Copyright © 2003 Society of Chemical Industry     

Synthesis of highly conjugated poly(3,9-carbazolyleneethynylenearylene)s emitting variously colored fluorescence

Novel conjugated polymers P1–P7 containing 3,9-linked carbazole units in the main chain were synthesized by the polycondensation of 3-ethynyl-9-(4-ethynylphenyl)carbazole (EEPCz) and dihaloarenes, and their optical and electrical properties were studied. Polymers with weight-average molecular weights of 4100–48,000 were obtained in 24–92% yields by the Sonogashira coupling polycondensation in tetrahydrofuran (THF)/Et₃N at 30 or 50 °C for 48 h. All the polymers absorbed light around 350 nm. The polymers with electron-accepter units exhibited absorption bands originating from charge transfer. The polymers except the one containing azobenzenes emitted variously colored fluorescence with moderate quantum yields upon excitation at the absorption maxima. P1–P3 were oxidized around 0.6 V, and then reduced around 0.5 V. The conductivity of P3 was 1.1 × 10⁻¹⁴ S/cm at 10³ V/cm.     

Synthesis and property studies of linear and kinked poly(pyreneethynylene)s

A series of fluorescent conjugated polymers, poly(pyreneethynylene)s, have been designed and synthesized to investigate the effect of shape of polymer backbone on physical properties. Polymers with linear and kinked backbone were synthesized using 1,6- and 1,8-disubstituted pyrene. The target copolymers were designed to incorporate various spacer units, such as, alkoxyphenyl, carbazole and fluorene on the polymer backbone. Characterization of the target compounds was achieved by NMR, IR, GPC and MALDI-TOF mass spectrometry. Detailed investigation on their optical, electrochemical and thermal properties revealed significant contribution of the geometry of polymer backbone towards physical properties. Kinked backbone of cisoid-polymers was found to result in lower optical band gap, less negative E_HOMO and higher thermal stability as compared to their linear analogues, most probably due to the coiling of polymer chains. Comparison of the physical properties of the polymers with those of the model compounds suggested similar extent of conjugation through 1,6- and 1,8-position of pyrene.     

Macro-counterions in a precursor to poly(phenylene vinylene): Toward defect-free luminescent films

Thermal elimination of a water soluble poly(xylylidene) precursor to poly(phenylene vinylene) (PPV) was accomplished in air at 80 °C using the macro-counterion poly(ethylene glycol)-4-nonylphenyl-3-sulfopropyl ether (PEGNOPS). The high relative photoluminescence efficiency was ascribed to the low carbonyl content, with a possible contribution from PPV chain separation, which minimizes radiationless interchain exciton formation. In addition, the PEGNOPS precursor showed no carbonyl formation on long term storage, in contrast to the precursors with dodecylbenzene sulfonate and chloride counterions.     

Synthesis and characterization of soluble poly(N-heptyl indole)

In view of preparing soluble polyindole, indole was N-alkylated using bromoheptane and polymerized to poly(N-heptyl indole) which is soluble in common organic solvents. This process is being reported for the first time. Poly(N-heptyl indole) was characterized by spectral, thermal methods and it shows photoluminescence in liquid state.     

Synthesis of sequential poly(1,3-phenyleneethynylene)-based polyradicals and through-space antiferromagnetic interaction of their solid state

Some 1,3-PPE-based polyradicals with pendent phenoxy radicals whose repeating unit consisted of four 1,3-phenyleneethynylene units were synthesized via polymerization between monomers and trimeric monomers in the presence of the Pd(PPh₃)₄ complex catalysts. The ESR spectra of the polyradicals in dichloromethane showed unimodal broad signals. For the solid samples which were prepared from the dichloromethane solution by evaporating the solvent and by drying in vacuo, the signal intensity decreased with broadening of peak-to-peak line-width (ΔH_pp). However, the ESR spectra almost recover to the initial intensity and shapes due to redissolving in dichloromethane. In particular, the decrease of doubly integrating the ESR signal (I_ESR) was more remarkable for the polyradical bearing galvinoxyl and phenoxyl residues than others. This behavior suggests that strong antiferromagnetic interaction partially arose for the polyradical.     

Thermal undoping behavior of FeCl3-doped poly(3-octylthiophene)

For neutral and FeCl₃-doped poly(3-octylthiophene) (P3OT), measurements of ⁵⁷Fe Mössbauer spectroscopy, conductivity, thermogravimetric analysis, differential scanning calorimetry and dynamic mechanical analysis are performed in order to understand the thermal undoping behavior. It is found that the counter anion for the doped P3OT is FeCl₄. At the doping level 0.33, its glass transition temperature (T_g) shifts from 11.2 °C at the neutral state to 137 °C. During the heat treatment, the aggregation of the dopant occurs between 65 to 150 °C (centered at 99 °C) and the decomposition of dopant anions occurs between 150 to 236 °C (centered at 188 °C). The aggregation of the dopant anion in the glass transition period is resulted from the increased ring distortion in the subchains, which leads to a slow decrease in conductivity. As the dopant anions decomposes, the conductivity drops sharply.     

Flexible electrochromic device based on poly (3,4-(2,2-dimethylpropylenedioxy)thiophene)

In this study, the design, fabrication and characterization of a flexible electrochromic device based on indium tin oxide (ITO) coated polyethylene terephthalate (PET) plastic is discussed. The working electrochromic material film was poly (3,4-(2,2-dimethylpropylenedioxy)thiophene) (PProDOT-Me₂), while the counter layer of the device was vanadium oxide titanium oxide (V₂O₅/TiO₂) composite film, which serves as an ion storage layer. A solution type electrolyte was used as the ionic transport layer and was sandwiched between the working and counter layers. The device exhibited tuneable light transmittance between transparent and deep blue color, with a maximum contrast ratio at 580 nm wavelength. Other important properties, such as switching speed, life time, and coloration efficiency have been improved.     

Synthesis of poly(p-phenylene vinylene) and derivatives via a new precursor route, the dithiocarbamate route

A new synthetic route towards poly(para-phenylene vinylene) (PPV) and its derivatives has been investigated. In this route, a bis-dithiocarbamate monomer is polymerized towards a dithiocarbamate precursor polymer by the addition of a strong base (LDA). The corresponding conjugated polymer is obtained via a heat treatment of the precursor polymer. This dithiocarbamate (DTC) precursor route strikes an optimal balance between several straightforward but sometimes troublesome precursor routes and the more complex sulphinyl precursor route yielding superior purity materials. The novelty lies in the fact that the monomer synthesis is not as difficult as compared to the sulphinyl route and this without losing the quality and accessibility of the precursor polymer. In the paper, the mechanism of the polymerization process is discussed and strong indications for radical as well as anionic mechanisms are presented.     

Electrochemical synthesis and characterization of poly[3-(ω-bromoalkyl)thiophene]s

A novel series of functionalized polythiophenes incorporating 3-(ω-bromoalkyl) pendants are synthesized by electrochemical polymerization. The effect of the solvent on the electrosynthesis is investigated. The polymeric films are characterized using cyclic voltammetry, FT-IR, AFM and SEM microscopy. The poly[3-(6-bromohexyl)thiophene] film cast on GC or ITO electrode surface is compared with a sample obtained by a chemical method.     

Structures and cocrystallization behavior of copolyesters based on poly(octamethylene terephthalate) and poly(octamethylene 2,6-naphthalate)

We have synthesized poly(octamethylene terephthalate) (POT), poly(octamethylene 2,6-naphthalate) (PON), and poly(octamethylene terephthalate-co-octamethylene 2,6-naphthalate)s [P(OT-co-ON)s] with various comonomer composition by melt-polycondensation reaction and investigated their chain structures, crystalline structures, melting and cocrystallization behavior by using ¹H NMR spectroscopy, wide angle X-ray diffraction (WAXD), and differential scanning calorimetry (DSC), respectively. It was observed that P(OT-co-ON)s exhibit clear melting and crystallization peaks in DSC thermograms and sharp diffraction peaks in WAXD patterns throughout the copolymer composition, resulting from the cocrystallization behavior of OT and ON units in copolymers. When the melting and crystallization temperatures of P(OT-co-ON)s are compared as a function of the copolymer composition, there exists an eutectic point at around 23 mol% ON, where the crystal transformation from POT-type to PON-type occurs. It was confirmed from WAXD patterns of the melt-crystallized samples that the crystal transformation from POT-type to PON α-type to PON β-type occurs with the increment of the comonomer ON content in copolymers, i.e., POT-type crystals for POT and P(OT-co-ON) with 11 mol% ON, PON α-type crystals for P(OT-co-ON)s with 23-48 mol% ON, and PON β-type crystals for PON and P(OT-co-ON)s with 62-87 mol% ON. Both DSC and WAXD results demonstrate the isodimorphic cocrystallization of P(OT-co-ON)s. Based on the Wendling-Suter model for cocrystallization thermodynamics, it was found that the average defect free energy for the inclusion of OT units into PON β-type crystals is much lower than the value of the incorporation of ON units into POT-type crystals.     

Characterization of surface compositions of phase-separated structures in conjugated poly(phenylene vinylene) blends by scanning near-field optical microscopy

The phase-separated structures in a thin-film conjugated polymer blend, poly(2-methoxy-5-(3,7-dimethyloctyloxy)-1,4-phenylenevinylene)/poly(methyl methacrylate) (MDMO-PPV/PMMA) was studied by scanning near-field optical microscopy (SNOM), which can probe both of the surface topography and the chemical composition at high spatial resolution. In thin films of MDMO-PPV/PMMA, the PMMA-rich phase with less fluorescent emission appeared as a raised structure while the MDMO-PPV-rich phase with highly fluorescent emission was present as a collapsed phase with a low height. Such the vertical structure of the phase separation was dependent on the solvent quality for each component. On the other hand, the lateral structure was determined by the surface property of the substrate. As the degree of hydrophobic character of the substrate increased, the PMMA domains tended to form a continuous form to a separated spherical form. This evolution arise from a change in affinity between the substrate surface and PMMA, which the hydrophilic substrate has higher affinity to PMMA for maintaining the continuous structures and the hydrophobic substrate with lower affinity to PMMA can not hold the structures continuously.     

New soluble unsaturated polyketone derived from diarylidenecycloalketone: synthesis and optical and electrochemical properties of π-conjugated poly(diarylidenecyclohexanone) with long side chains

A new type of unsaturated polyketone having cyclohexanone moiety in a π-conjugated main chain was prepared by polycondensation between 2,6-bis(4-bromobenzylidene)cyclohexanone and 2,5-dihexyloxy-p-phenylene diboric ester in the presence of Pd(PPh₃)₄. The polymer had good solubility in common organic solvents. Analysis by gel permeation chromatography (GPC; polystyrene standards) showed that the polymer had M_n and M_w values of 7800 and 18?200, respectively. The polymer exhibited a [η] value of 0.70 dl g⁻¹ in benzene at 30 °C. The chloroform solution of the polymer showed an UV-Vis peak at 392 nm, and the PL spectrum gave a peak at 533 nm. DSC exhibited that the polymer had a T_g of 85 °C. The DSC data, observation with a polarizing microscope, X-ray diffraction data and UV-Vis data of the obtained polymer showed a phase transition above 200 °C. TGA showed that the polymer had good thermal stability with 5 wt% loss temperature of 407 °C under N₂. Electrochemical oxidation (or p-doping) of the polymer started at about 0.7 V vs. Ag/AgNO₃ and gave a peak at 1.06 V vs. Ag/AgNO₃ with a color change of the film from yellow to deep red. The color change was followed by UV-Vis spectroscopy. The corresponding p-dedoping peak appeared at 0.58 V vs. Ag/AgNO₃.     

Impact of fluorinated vinylene units on supramolecular organization and optical properties of poly(p-phenylenedifluorovinylene) thin films as a class of blue band gap conjugated polymers

This study is an investigation on the interplay between supramolecular organization and optical properties of thin films of conjugated polymers with fluorinated vinylene units such as poly[2-(2-ethylhexyloxy)-5-methoxy]-1,4-phenylenedifluorovinylene (MEH-PPDFV) and poly(2-methoxy-5-propyloxysulfonatephenylenedifluorovinylene) (MPS-PPDFV), which are both PPV polymers with fluorinated double bonds with alkoxy chains in the 2 and 5 positions. MEH-PPDFV is the fluorinated version of the widely investigated MEH-PPV, and MPS-PPDFV is characterized by the presence of ionic alkoxy side chains. This interplay is elucidated exploiting atomic force microscopy, spectroscopic ellipsometry and photoluminescence to obtain complementary information. It is demonstrated that the presence of F-atoms in the vinylene units of the MEH-PPDFV yields a blue optical band gap with the maximum of the fundamental HOMO-LUMO transition and of the room temperature photoluminescence at 3.74 eV (331 nm) and at 2.71 eV (458 nm), respectively. The blue-absorption and emission in the thin films are ascribed to the fact that fluorine atoms on the vinylene units prevent π-stacking of polymeric chains. Furthermore, the dependence of morphology, anisotropy in optical properties and photoluminescence properties of films on deposition methodology is also discussed. MEH-PPDFV also emits homogeneous blue-greenish electroluminescence at 2.46 eV (504 nm).     

Electrochemical Polymerization of Thiophene and Poly(3-hexyl)thiophene,Nanocomposites with TiO2, and Corrosion Protection Behaviors

Thiophene, 3-hexylthiophene, and their nanocomposites with TiO₂ were electropolymerized on Al1050 electrode by chronoamperometric technique. Different concentrations of thiophene and 3-hexylthiophene homopolymers and their nanocomposites with TiO₂ (2% in total content) were characterized by attenuated total reflection Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersion X-ray analysis, and electrochemical impedance spectroscopy. The anticorrosion tests for homopolymers and nanocomposite films were examined on Al1050 in 3.5% NaCl solution. Poly(3-hexylthiophene)/TiO₂ nanocomposite films gave the highest protection efficiency of 98% because the amount of defects was much lower than that for the poly(3-hexylthiophene), polythiophene, and polythiophene/TiO₂ films.