Electrochromic performance and ion sensitivity of a terthienyl based fluorescent polymer

A novel terthienyl based fluorescent polymer bearing strong electron-withdrawing substituents directly attached to the 3,4-positions of the central thiophene ring was synthesized by electrochemical polymerization of diethyl 2,5-di(3,4-ethylenedioxythiophen-2-yl)thiophene-3,4-dicarboxylate. The corresponding polymer was characterized by cyclic voltammetry, FT-IR and UV–vis spectroscopy. The polymer has a well-defined redox process (E_p,1/2 = 0.74 V) and demonstrates a reversible electrochromic behavior; lilac in the neutral state and transparent sky blue in the oxidized state. Also, the polymer had low band gap (E_g = 1.82 eV) and high redox stability (retaining 94.0% of its electro-activity after 500th switch). Moreover, the sensitivity of both the monomer and its polymer towards metal cations was investigated by monitoring the change in the fluorescence intensity. Among various common ions both the monomer and its polymer were found to be selective towards Cu²⁺ and Cu⁺ ions by quenching the fluorescence efficiency with a Stern–Volmer constant (K_sv) of (1.4–1.6 × 10³ M^?1) and (1.5–1.8 × 10² M^?1) for monomer and polymer solutions, respectively.     

A novel polymer electrolyte based on PMAML/PVDF-HFP blend

A gel polymer electrolyte based on the blend of poly(methyl methacrylate-co-acrylonitrile-co-lithium methacrylate) (PMAML) and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) was prepared and characterized. The synthesized PMAML were characterized by FTIR and NMR, respectively, and the surface morphology of the PMAML and PVDF-HFP blend membrane was also observed by scanning electron microscope (SEM). The electrochemical properties of composite electrolyte membranes were studied. The ionic conductivity of the polymer electrolyte composed of 75 wt.% 1 M LiBF₄ in ethylene carbonate (EC) and dimethyl carbonate (DMC) (EC:DMC=1:1 by weight) was about 2.6×10⁻³ S cm⁻¹ at ambient temperature. The electrochemical window of the polymer electrolyte was about 4.6 V determined from the linear sweep voltammetry plot. The lithium ion polymer batteries were assembled by sandwiching gel polymer electrolyte between LiCoO₂ cathode and mesophase carbon fibre (MPCF) anode. Charge-discharge test results display that lithium ion batteries with these gel polymer electrolytes have good electrochemical performance.     

A novel emitting polymer with bipolar carrier transporting abilities

A luminescent bipolar polymer containing 1,3,4‐oxadiazole and triphenylamine has been synthesized. A smooth and dense thin film of polymer is easily obtained by spin coating its chloroform solution. This film exhibits a strong blue fluorescence under the irritation of ultraviolet (UV) light. The synthesized polymer possesses a high glass transition temperature (T_g) of 167°C. A single‐layer electroluminescence (EL) device indium‐tin oxide (ITO)/polymer/Mg:Ag emitted blue light with a turn‐on voltage of 13 V. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88:50–53, 2003     

A novel porous coordination polymer based on rigid and flexible organic ligands

A novel bilayered coordination polymer with nanoporous channels [Ni₃(bix)₃(PTCO)₂ (H₂O)₄·6H₂O]_n (1) has been synthesized and the permanent porosity of (1) is confirmed by N₂ adsorption isotherm measurement.     

A novel polymer electrolyte based on polydioxolane polyurethane with Na+ single‐ionic conductivity

A series of novel polyurethane ionomers with polydioxolane (PDXL) as soft segment was prepared and characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, and dynamic mechanical analysis. The ionomers obtained were Na⁺ single‐ionic conductors. Their ionic conductivity and water absorption were tested. At medium temperature (> 75°C), the conductivity of ∼ 10⁻⁵ s cm⁻¹ was reached. The temperature dependence of conductivity could not be well expressed by both Arrhenius and VTF equations. When ionization level was fixed, the conductivity increased as the Mn of PDXL decreased. We also discussed the effect of ionization level on water absorption. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1711–1719, 1999     

A novel parameter of polymer structure

A need exists for a simple and reliable heterogeneity index to determine the presence of high molecular weight components which may be branched in complex polymers and copolymers. On the basis of theoretical considerations, a proposal is made to employ the ratio of concentrated solution to intrinsic or Mooney viscosity as a heterogeneity index. The basis for the index is that the concentrated solution or melt viscosity is a function of a higher moment of the molecular weight distribution than either the intrinsic or Mooney viscosity. Experimental evidence in the form of light-scattering measurements and osmometry support the validity of the index when the range of intrinsic viscosities is narrow and other assumptions cited are justified. It is further shown that the heterogeneity index correlates well with the processibility of cis-polybutadiene.     

A novel conjugated polymer based on cyclopenta[def]phenanthrene backbone with spiro group

Poly(2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[def]phenanthrene)) (PCPP) is a stable blue light emitting conjugated polymer even after annealing at 150 °C or operation of the device in air. The spiro form of PCPP, poly(2,6-(3′,6′-bis(2-ethylhexyloxy)-4,4′-spirobi(4H-cyclopenta[def]phenanthrene))) (spiro-PCPP), has been synthesized by Yamamoto polymerization. The PL emission spectrum of the polymer in THF solution shows a maximum peak at 398 nm, nearly identical with that of PCPP. The PL spectrum of the polymer in the solid state exhibits a maximum peak at 451 nm, which is red-shifted over 50 nm from that of the solution, due to the inter-chain interaction of the polymers. The PL spectra of spiro-PCPP in the mixture of THF and MeOH from 9:1 to 3:7 ratios showed increasing peaks at 458 and 484 nm. With an increased ratio of the hydrophilic solvent (MeOH), the inter-chain interaction of the hydrophobic polymers was enhanced to show peaks at 458 and 484 nm. This phenomenon has the same tendency as compared to the PL spectrum in solid thin film state. The polymer LED with the configuration of ITO/PEDOT/spiro-PCPP/Ca:Al emitted light with maximum peaks at around 463 nm. The emission color of the spiro-PCPP device is sky blue with the CIE coordinates of (0.14, 0.15), which are close to those of the standard blue (0.14, 0.08).     

A novel polymerizable pigment based on surfactant-encapsulated polyoxometalates and their application in polymer coloration

A novel polymerizable pigment based on polymerizable surfactant-encapsulated polyoxometalate complexes has been developed. While retaining the intrinsic colors of polyoxometalates, the complexes are organically compatible and are readily incorporated into polymer matrices by means of copolymerization. During the copolymerization process, the complexes can covalently graft onto polymer chains, creating a molecular hybrid between the complexes and polymer matrices, thereby effectively avoiding phase separation between the two components which results in high transparency of the colored polymer. In addition, the complexes exhibit good coloration efficacy, provide stable colors and have little effect on polymer processibility.     

A novel heterometallic BaGa coordination polymer based on the bifunctional ligand 2,5-pyridine dicarboxylic acid

The first heterometallic BaGa coordination polymer (CP), namely [Ba₂Ga₂(pydc)₄(OH)₂(H₂O)₂]·3H₂O (1) (H₂pydc = 2.5-pyridine dicarboxylic acid), has been successfully synthesized by the reaction of the bifunctional ligand H₂pydc, BaCl₂·2H₂O and Ga₂O₃ under hydrothermal conditions. Single-crystal X-ray diffraction analysis reveals that compound 1 features a three-dimensional (3D) network structure constructed from Ga₂(OH)₂ dimers incorporated Ba-pydc skeletons. Luminescence measurements showed that 1 exhibited strong emission band centered at 412 nm ascribed to the emission of ligand-to-ligand charge transfer, which was confirmed by theoretical studies.     

A novel heterostranded double-helical coordination polymer with chiral channels emitting blue fluorescence

A novel heterostranded double-helical coordination polymer is self-assembly from two flexible ligands, 4-carboxymethylbenzoic acid (H₂L) and 1,1′-(1,4-butanediyl)bis(imidazole) (abbr. as bbi), with Zn²⁺ ion under solvent-thermal condition. The heterostranded double-helix constructs a chiral channel, which is filled by lattice water molecules; the adjacent heterostranded double-helical channels share Zn²⁺ ions to develop into a homochiral helical two-dimensional sheet, and the right- and left-handed chiral sheets further array in an alternating fashion to generate a racemic crystal via van de Waals forces. This coordination polymer emits blue fluorescence in the solid state.     

A novel method to prepare high-resistivity polymer composites

A novel method was developed for the preparation of high-resistivity conductive polymer composites reproducibly. The conventional method which involves the simple mixing of a conductive filler and a polymer usually produces a conductive polymer composite having a loading curve with a region in which the resistivity changes rapidly as the filler concentration changes. Hence, it is very difficult to obtain reproducible materials in that region. This newly developed method involves the preparation of a conventional conductive polymer composite, which is prepared by the simple mixing of carbon black and a polymer as the first step. The resulting compound, which is crosslinked by either electron-beam radiation or a chemical-crosslinking agent, is ground into a fine powder (composite filler) with the particle size less than 250 microns. The composite filler is mixed with another polymer to form a conductive particulate composite which has a loading curve showing a more gradual change of resistivity as a function of filler concentration. The modification of the loading curve is controlled by the resistivity, the shape, and the size of the composite filler.     

Dielectric properties of a novel high absorbing onion-like-carbon based polymer composite

A novel lightweight onion-like carbon (OLC) based Poly(methyl metacrylate) (PMMA) composite with high electromagnetic (EM) absorption capability determined earlier in microwave range is studied in low frequencies from 20 Hz to 1 MHz by dielectric spectroscopy. The investigation of dielectric properties of PMMA films with incorporated OLC in small concentration (0.5–2 wt.%) have been carried out by varying the temperature between 240 and 520 K. The temperature behavior of the complex permittivity at a given frequency is found to be strongly dependent on the OLC concentration. The experimental data are in quantitative agreement with the results of modified effective medium calculations of OLC-based polymer film's permittivity. Both the experimental observations and theoretical simulation demonstrate that small additions of onion-like carbon particles to a polymer matrix can noticeably modify the composite response to low-frequency EM radiation as well as improve its thermal stability (increased glass transition and melting temperatures, correspondingly).     

丙炔基双酚A醚硼聚合物热解过程的ReaxFF分子动力学模拟

聚合物的热解过程涉及的化学反应较为复杂,难以通过测试表征的手段深入探究其机理。本研究在实验表征的基础上,结合ReaxFF分子动力学(ReaxFF-MD)模拟方法,研究了丙炔基双酚A醚硼聚合物(PB)的热解过程。通过观察升温过程中PB的结构变化,可得到其热解过程中的断键顺序。此外,采用ReaxFF-MD模拟,其研究结果不仅验证了实验中热重-红外光谱联用(TG-FTIR)分析所得的PB热解生成小分子的主要组成为CH₄、H₂O、H₂ 和 CO,并且通过追踪上述小分子的生成过程可得到其主要的生成途径。以上研究结果表明,ReaxFF-MD模拟方法不仅有助于理解PB聚合物的热解机理,直观地反映出其热解产物生成途径,而且对聚合物耐热性能的研究有所借鉴。     

A novel optical aerosol detector utilizing an optic fiber with conductive polymer coating

The detection of atmospheric aerosol particles is becoming an important issue in many fields such as environmental science, occupational medicine, semiconductor industry and material science. In the present paper, we utilized the conductive polymer, polypyrrole (PPy), as a sensitive membrane for detecting aerosol particles optically. A polymer optical fiber reflectance probe is constructed by depositing the PPy nanofilm at the end face of the fiber. The sensor principle relies on the change in the refractive index of the PPy nanofilm upon its interaction with aerosol nanoparticles and on the electrostatic induction between aerosol particles and the PPy nanofilm, which leads to a change in the reflected intensity. For preliminary evaluation of optical aerosol detector, three types of aerosol particles, NaCl, black carbon (BC) and polystyrene latex (PSL), are selected. The fabricated fiber optic reflectance probe using the PPy nanofilm shows distinct variations in the reflected light intensity depending on the type of aerosol particle and its properties. The proposed sensing approach may promote the use of conductive polymers in optical techniques for the detection of atmospheric aerosols.     

A novel PEO-based composite polymer electrolyte with absorptive glass mat for Li-ion batteries

A novel PEO (polyethylene oxide)-based composite polymer electrolyte (CPE) using absorptive glass mat (AGM) as filler was prepared and characterized. Scanning electronic micrograph (SEM) images showed that the addition of Li salt and modified AGM may improve the surface morphology of CPE. The results of Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and differential scanning calorimeters (DSC) indicated that the inclusion of LiClO₄ salt and the addition of AGM filler can reduce the crystallinity of PEO. It was concluded that the addition of AGM plays two roles in PEO-based CPEs, namely, interruption of the PEO recrystallization and reinforcement of CPEs, accordingly enhancing room temperature ionic conductivity of CPEs and improving its mechanical strength and electrochemical stability at high temperatures.     

A novel approach in preparing polymer/nano-CaCO composites

An novel compounding process using nano-CaCO₃ aqueous suspension for preparing polymer/nano-CaCO₃ composites with nanoparticles dispersed at the nanoscale is reported. The process is called the mild mixing method. In this method, the pre-dispersed nanoparticle suspensions are blended with melting polymers in a weak shearing field using an extruder, followed by removing the water from the vent. The four typical polymeric nanocomposites were prepared by mild mixing method. The dispersion of nano-CaCO₃ in the matrix of the polymer at the nanoscale was confirmed by scanning electron microscopy (SEM). The molecular weights of polycarbonate (PC) and its nanocomposite showed that the degradation had not occurred during the mild mixing processing. The mechanical properties of the composite with 1.5 wt-% nano-CaCO₃ improve slightly. It proved that this approach is suitable for the preparation of nanocomposites based on both polar and non-polar polymers.     

A novel method of selecting solvents for polymer electrospinning

The selection of a desirable solvent or solvent system as the carrier of a particular polymer is fundamental for the optimisation of electrospinning. Solvent selection is pivotal in determining the critical minimum solution concentration to allow the transition from electrospraying to electrospinning, thereby significantly affecting solution spinnability and the morphology of the electrospun fibres. 28 solvents diversely positioned on the Teas graph were studied for their solubility and electrospinnability for making polymethylsilsesquioxane (PMSQ) solutions. The results are combined and mapped on the Teas graph using different colour codes. Based on this new spinnability-solubility map, various solvent systems for PMSQ are methodically developed. Solvents are selected to produce binary solvent systems that have solvent parameters close to a good single solvent for electrospinning of the polymer solution. This work shows that solvents of high solubility do not necessarily produce solutions good for electrospinning. Polymethylsilsesquioxane solutions of the same concentration in solvents of partial solubility showed better spinnability than solutions in solvents of high solubility. A methanol-propanol binary solvent system produced electrospun fibres with high surface porosity, showing that high volatility and high vapour pressure difference among solvents mixed can induce phase separation in electrospinning. It is noteworthy that the binary solvent system mixing 2-nitropropane (high solubility) and dimethylsulphoxide (non-solvent), neither of which exhibited high volatility, also produced highly porous electrospun fibres. This demonstrates that phase separation can be induced by solubility difference in the electrospun polymer solution.     

A novel electrochromic polymer containing triphenylamine derivative and pyrrole

A novel conducting polymer was successfully synthesized via electropolymerization of N¹,N⁴-bis(4-(1H-pyrrol-1-yl)phenyl)-N¹,N⁴-diphenylbenzene-1,4-diamine (DPTPA). This polymer film exhibited six various colors under different potentials. Besides, this polymer film showed high optical contrast (41% at 852 nm, 52% at 617 nm) and fast switching time (1.3 s at 410 nm, 1.4 s at 852 nm and 0.6 s at 617 nm). Cyclic voltammogram and electro-optical study showed that the polymer film has a stable and well-defined reversible redox process as well as electrochromic behavior.     

A novel approach to viscometric parameters of polymer solutions

A three-parameter equation is put forward to evaluate the [η] of polymer solution from a wide range of concentrations, up to a relative viscosity of 100. The equation is tested by viscometric data of polystyrene, poly(vinyl chloride), poly(1-vinylnaphthalene), poly(2-vinylnaphthalene), and poly(4-vinylbiphenyl) at different temperatures and in a variety of solvents including mixed solvents. A statistical method is employed to analyze the experimental data. It is found that the values of [η] obtained by the new equation are consistently lower than those derived from the Huggins equation. However, the discrepancy is not more than 3% on average, and it does not affect the values of Mark-Houwink constants significantly. Other parameters of the equation are also computed.     

A novel solid polymer electrolyte: Synthesis and characterization

Summary A new polyether network was prepared using a polyethylene oxide (PEO) triol and a PEO diisocyanate, the latter component arising from the chemical modification of commercial PEO diamines. The physico-chemical properties of the network alone and with LiClO₄ were assessed in comparison with those of previously obtained structures. Ionic conductivities were found to be higher with this new system. Replacement of LiClO₄ by LiN(CF₃SO₂)₂ improved the conductivity further because of the plasticizing role of the imidic anion.