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Three low band gap thienopyridazine-based donor–acceptor conjugated polymers, PDTTPTT, PDTTPBT, and PDTTPBDT were synthesized by the Stille copolymerization of thienopyridazine with thienothiophene, benzodithiophene, and bithiophene, respectively. The optical band gaps of PDTTPTT, PDTTPBT, and PDTTPBDT polymers were determined as 1.41 eV, 1.43 eV, and 1.58 eV, respectively by UV absorption. The deep HOMO level of the three polymers was determined by cyclic voltammetry. The three polymers were fabricated to form organic field-effect transistors and their performance as p-type semiconductors were studied.

A novel cyclodextrin intermediate, mono-2(A)-allylcarbamido-2(A)-deoxy-permethylated β-cyclodextrin, was synthesized by reacting allylamine and newly prepared mono-2(A)-azido-2(A)-deoxy-permethylated β-cyclodextrin by the Staudinger reaction and anchored onto porous silica beads by a one-pot hydrosilylation and immobilization procedure to afford a novel chiral stationary phase. This stationary phase acts as a new member of the previous chiral stationary phase series immobilized on the cyclodextrin C2 position. This stationary phase depicted enantiomeric separation abilities toward a series of bicyclic and tricyclic racemates under reversed-phase conditions. The resolutions for hesperetin and naringenin achieved on the current phase reached 3.91 and 1.11, respectively, much higher than the previous permethylated β-cyclodextrin with the linkage at the C6 position.

Multi-walled carbon nanotubes are functionalized with triazole moieties using ‘click’ chemistry and successfully incorporated into a polyurethane nano-composite by in situ polymerization. It is found that the functionalized multi-walled carbon nanotubes provide enhanced interactions with the polyurethane matrix. In addition, incorporation of the triazole moieties into the polyurethane nano-composites significantly increases their heat of decomposition.

5,6-Difluorobenzo[c][1,2,5]thiadiazole (FBT)-based conjugated donor–acceptor (D-A) polymers with straight and branched side chains were synthesized via Stille-coupling copolymerization to study their physical, optoelectronic and photovoltaic properties. The results show that both the nature of pendant side chains and the electron acceptor strength of the acceptor moiety of D–A polymers have critical impacts on material and photovoltaic properties. Better π–π stacking of polymer backbones enabled by appropriate substituents such as fluorine atoms and branched alkyl chains leads to a reasonably high power conversion efficiency of over 6% when the polymer is utilized as a donor material with PC71BM as an active layer in bulk heterojunction solar cells.

A novel cationic cyclodextrin, mono-6(A)-(2-hydroxyethyl-1-ammonium)-6(A)-β-cyclodextrin chloride (HEtAMCD) has been successfully synthesized and applied as chiral selector in capillary electrophoresis. The NMR study revealed this chiral selector has three recognition sites: β-CD, ammonium cation and hydroxy group in the sidearm to contribute three corresponding driving forces including inclusion complexation, electrostatic interaction and hydrogen bonding. The effect of buffer pH and HEtAMCD concentration (2.5-10 mM) on enantioselectivity, chiral resolution as well as effective mobility of analytes was investigated. This elegantly designed CD exhibits outstanding enantioselectivities toward the studied hydroxyl acids and ampholytic racemates in CE with the aid of extra hydrogen bonding. Under optimum pH 6.0, chiral resolutions over 5 can be readily obtained for hydroxy acids with CD concentration below 5mM. The comparison study between HEtAMCD and our earlier reported ammonium CDs indicates the hydroxyethylammonium group of HEtAMCD significantly increased the enantioselective capability.

A novel perylene bisimide derivative, N, N′-Bis(9, 9, 9′, 9′-tetraoctyl-bisfluoren-2-yl)-3, 4:9, 10-perylene bisimide (BFPBF) , has been successfully synthesized via a condensation reaction. The new compound having a donor–acceptor–donor (D–A–D) structure is soluble in common organic solvents such as chloroform and toluene and thus can be easily processed by wet techniques such as spin-coating. BFPBF is thermally stable with a decomposition temperature ( T d ) above 430 °C and exhibits a glass transition temperature ( T g ) of 160 °C under nitrogen atmosphere. Electrochemical investigation indicates that BFPBF has a LUMO level of −4.07 eV which is similar to that of [6,6]-phenyl C 61 butyric acid methyl ester ( PCBM ). Bulk heterojunction photovoltaic device was fabricated using a blend of poly(3-hexylthiophene) (P3HT) and BFPBF (1:1, w-w) as an active layer and power conversion efficiency of the device was 0.13% under simulated solar light AM 1.5 G (100 mW/cm 2 ).

Three new alternating conjugated polymers consisting of pyrene and 3-dodecylthiophene (PPyMT), 4,4'-didodecyl-2,2'-bithiophene (PPyBT), or 9,9-didodecylfluorene (PPyFlu) moieties have been prepared using Suzuki coupling reaction or Sugimoto approaches. The polymers were readily soluble in common organic solvents and exhibited good thermal stability in nitrogen and air atmospheres. The structures and optical properties of the polymers were characterized by NMR, FTIR, XRD, UV-vis, and fluorescence spectroscopy. PPyMT and PPYBT showed blue-light emission in solution, whereas PPyFlu performed blue-light emitting in film state. The polymers exhibited an intermolecular aggregation and structural ordering due to pyrene-pyrene π-π stacking interaction.

Poly{[N-dodecyl-dithieno(3,2-b:2′,3′-d)pyrrole-2,6-diyl]-alt-[2,1,3-benzothiadiazole-4,7-diyl]} ( PBTDTP ) was successfully prepared via Stille coupling. The new polymer is soluble in common organic solvents such as chloroform (CHCl 3 ), tetrahydrofuran (THF) and o-dichlorobenzene. Compared with N-alkyl dithieno[3,2-b:2′,3′-d]pyrrole (DTP) homopolymer, the maximum absorption of PBTDTP was red-shifted approximately 40 nm. The optical band gap of the polymer in film state is 1.55 eV calculated from the onset of absorption spectrum. The cyclic voltammetry measurements of the polymer depicted a HOMO energy level of −5.0 eV and a LUMO energy level of −3.3 eV of PBTDTP . This work demonstrates that this newly synthesized polymer is a promising p-type material for application in bulk hetero-junction organic solar cells.

Novel donor-acceptor type polymers consisting of alternating quaterthiophene and an electron withdrawing moiety, pyrazinyl or pyridinyl, have been prepared using Stille coupling approach with moderate yields. The polymers were highly soluble in common organic solvents such as tetrahydrofuran and chloroform. The structure and optical properties of the polymers were characterized by NMR, UV-vis and fluorescence spectroscopy, and cyclic voltammetry, respectively. The polymer having pyrazine unit exhibited a red-shift in both absorption and emission in comparison with those analogs containing pyridine because of strong electron withdrawing character of the pyrazinyl group. The polymer containing pyrazinyl as acceptor units also depicted decrease in its optical and electrochemical bandgap relative to those polymers containing 2,5- or 2,6-pyridine moieties. The electrochemical behavior showed facile n-doping and p-doping properties of those polymers consisting of alternating quaterthiophene and the acceptor moiety.

Allyl phenyl thiophene ether as novel potential dielectric materials for organic thin film transistors have been synthesized by coupling 2-bromothiophene with 4-bromo allyl phenyl ether and was systematically characterized by elemental analysis and NMR. 4-bromo allyl phenyl ether was synthesized by the reaction between 4-bromophenol and allyl bromide. Self assembled mono-layers of these materials have been covalently grafted onto (111) hydrogenated silicon surfaces through thermal hydrosilation with the alkene end by Si–C bonding mechanism. Monolayer formation was carried out using solutions of the alkene in the high boiling point solvent 1,3,5-triethylbenzene and was characterized by X-ray photoelectron spectroscopy (XPS), contact angle, Atomic Force Microscopy(AFM) and Scanning Tunneling Microscopy (STM). We anticipate these monolayers as potential dielectric materials for organic electronics

Ionic hydrogels are attractive for the protection, delivery and controlled release of charged biomacromolecules such as proteins, growth factors or DNA. We have preparted and characterized a series of photocrosslinked anionic hydrogels based on water soluble methacrylated (MA) O-carboxymethylchitosan (OCMCS) and polyethylene glycol (PEG) diacrylate. OCMCS samples with varying degree of substitution of carboxymethyl group ranging from 0.69 to 1.86 were prepared by reacting native chitosan with different amounts of monochloroacetic acid. The OCMCS products demonstrated differences in solubility, zeta potential (-52.7 to -12.8 mV) and thermal decomposition temperature (260 to 283 degrees C). The OCMCS products were then reacted with glycidyl methacrylate to make ultra-violet (UV) crosslinkable OCMCS-MAs which were blended with PEG diacrylate, a photoinitiator and water and successfully photocrosslinked to create OCMCS-MA/PEG hydrogels. Water uptake of the hydrogels varied between 226 % to 358 % and the porous structures of the prepared OCMCS-MA/PEG hydrogels could be modulated by the degree of methacrylation. All the OCMCS-MA/PEG hydrogel substrates similarly supported attachment and proliferation of Smooth Muscle Cells (SMCs). The in vitro biodegradation of these hydrogels, in the presence of SMCs, could be controlled by the degree of methacrylation; weight loss after 9-week was (15+/-1) % and (19+/-2) % using OCMCS 4-MA (12.7 % MA) and OCMCS 1-MA (4.6 % MA), respectively. In addition, the hydrogel based on the most anionic OCMCS 1 showed higher adsorption of basic TGF-beta(1) than similarly modified -agarose, -dextran, and -chondroitin sulfate hydrogels.

A novel series of AB-type polymers comprised of alternating carbazolyl and pyridinyl units were synthesized using palladium(0)-catalyzed Suzuki cross-coupling reaction in good to high yields. In this series of alternating copolymers, the electron-rich 2,7-(N-(2-ethylhexyl)carbazolyl) unit was used as a light-emitting unit, and the electron-deficient unit of pyridinyl was introduced to tune the wavelength of the emitting light and improve their electron transportation. These polymers were characterized by 1H NMR and 13C NMR, gel permeation chromatography (GPC), thermal analysis, UV−vis, fluorescence spectroscopy, and cyclic voltammetry (CV). The glass transition temperature of these polymers ranged from 120 to 150 °C, and the polymers showed high thermal stability with decomposition temperatures in the range 370−400 °C in nitrogen. The different linkage pattern of pyridinyl units in the copolymer backbone has a significant effect on the electronic and optical properties in solution and in film phases. For ...

Aniline was polymerized with oxidant ammonium peroxydisulfate in aqueous medium comprising poly(ɛ-caprolactone)-poly(ethylene oxide)-poly(ɛ-caprolactone) (PCL-PEO-PCL) amphiphilic triblock copolymer micelles. Micelle size was found to influence the morphology of polyaniline (PANI) nanoparticles greatly. PANI synthesized in PCL-PEO(10000)-PCL and PCL-PEO(4000)-PCL micelles exhibited ordinary solid spherical shape, while PANI synthesized in PCL-PEO(1000)-PCL micelles exhibited hollow sphere structure. A possible explanation was offered to interpret the formation of the hollow spheres. The chemical structure of PANI was characterized with FT-IR and UV-vis spectra. The conductivity of PANI was found to depend on the regular distribution of conducting phase and the structure of PANI prepared in PCL-PEO-PCL micelles.

A novel series of well-defined soluble poly[2,7-(9,9-dialkyfluorenyl)-alt-pyridinyl] (except for PDHFP-25, a polymer with same composition but different weight-average molecular mass ( M w ) was reported in reference [B. Liu, W.L. Yu, Y.H. Lai, W. Huang, Chem. Mater. 13 (2001), 1984–1991] were synthesized using palladium-catalyzed Suzuki cross-coupling reactions in good to high yields. In the series of alternating copolymers, 2,7-(9,9-dialkylfluorenyl) was used as the light emitting unit and the electron deficient pyridinyl unit was employed to provide improved electron transportation. All these polymers were characterized by 1 H NMR, 13 C NMR, GPC, thermal analyses, UV–vis and fluorescence spectroscopy. The shorter pendant 9,9-dihexyl at fluorenyl unit is better to polymer for higher thermal stability and higher T g than 9,9-dioctyl at fluorenyl unit. The meta-linkage (3,5- or 2,6-linkage) of pyridinyl units in the polymer backbone is more favourable to polymer for pure blue emission and prevention of aggregation of polymer chain than the para-linkage (2,5-linkage) of the pyridinyl units.

Four new chiral stationary phases based on mono-(6 A -allylcarbamido-6 A -deoxy)-arylcarbamoylated β-cyclodextrin were synthesized. The chiral stationary phase of phenylcarbamoylated β-cyclodextrin exhibited excellent separation capability for a variety of chiral compounds. Compared with the previous work, it was found that the spacer remained on the surface of the silica gel and decreased the enantioseparation capability.

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

Alkylthio(SR)-functionalized polymers poly(3-alkylthio-2,5-thiophenediyl-1,4-phenylene-alt-4-alkylthio-2,5-thiophenediyl-1,4-phenylene) (P1, alkyl = butyl, octyl and dodecyl) and poly[4,4′-bis(alkylthio)-2,2′-bithiophene-5,5′-diyl-alt-1,4-phenylene] (P2, alkyl = butyl, octyl and dodecyl) have been synthesized by Grignard coupling and FeCl3 oxidation methods, respectively. Spectral measurements indicate that they are highly fluorescent, with quantum yields comparable to those of their alkyl(R)-functionalized analogues, poly(3-alkyl-2,5-thiophenediyl-1,4-phenylene-alt-4-alkyl-2,5-thiophenediyl-1,4-phenylene) (P1′, alkyl = butyl, octyl and dodecyl) and poly(4,4′-dialkyl-2,2′-bithiophene-5,5′-diyl-alt-1,4-phenylene) (P2′, alkyl = butyl, octyl and dodecyl). P1 and P2 are thermally less stable than P1′ and P2′, because of the alkylthio group instead of an alkyl group. Modulated differential scanning calorimetry (MDSC) studies reveal a plasticizing effect exerted by the long side chains on the glass transitions ...

Three π-acid type chiral stationary phases based on monochloro-substituted phenyl carbamates of β-cyclodextrin have been synthesized. First, β-cyclodextrin was reacted with 5-bromo-1-pentene in dry DMF at room temperature to give 6A-O-(4′-pentenyl)-β-cyclodextrin. The remaining twenty hydroxyl groups of this derivatized β-cyclodextrin were blocked by further reaction with 2-chlorophenyl isocyanate, 3-chlorophenyl isocyanate, and 4-chlorophenyl isocyanate in dry pyridine, at 85 °C, to yield the three corresponding carbamates. After hydrosilylation with triethoxysilane at 80 °C, catalysed by tetra(triphenylphosphine)platinum(0), these carbamates were anchored on to silica gel by heating under reflux in toluene. All the β-cyclodextrin derivatives and CSPs prepared were characterized by IR and 1H NMR spectroscopy and elemental analysis. The surface concentrations of 2-chlorophenyl carbamoylated β-cyclodextrin, 3-chlorophenyl carbamoylated β-cyclodextrin, and 4-chlorophenyl carbamoylated β-cyclodextrin on silica gel were 0.27, 0.28 and 0.30 μmol m–2, respectively. Under normal-phase conditions the separation ability of CSPs containing 3- and 4-chlorophenyl carbamate was better than that of the CSPs containing 2-chlorophenyl carbamate.

A novel series of conjugated polymers comprising alternating π-excessive bis(3-alkylthiophene) and π-deficient 2,5-pyridine (or 2,6- or 3,5-pyridine) moieties were synthesized using a Stille coupling approach and characterized by FT-IR, NMR, UV−vis, fluorescence spectroscopy, gel permeation chromatography (GPC), thermogravimetric analysis (TGA), electrochemical analysis, and X-ray photoelectron spectroscopy (XPS). The derived polymers were highly soluble in common organic solvents and trifloroacetic acid. The electronic and optical properties of these polymers were closely related to the polymer backbone structures. Polymers containing 2,6-/3,5-pyridine moieties exhibited blue shifts in UV and fluorescent spectra relative to those containing 2,5-pyridine analogues, and polymers containing 3,5-pyridine units depicted the highest thermal stability, UV absorption energy, fluorescence energy, and reduction potentials. The electrochemical behavior of these new polymers showed facile n-doping and p-doping prope...

Thiophenes substituted by alkylthio (hexylthio and dodecylthio) pedant groups were polymerized using the FeCl3 oxidation method. The polymers were characterized using microanalyses, conductivity measurements, thermogravimetry (TG) and 1 H NMR, UV-Vis, FTIR and XPS. The polymers are regiorandom in structure as expected and have a head-to-tail (HT) content of about 80% based on the 1 H NMR spectrum. Poly[(3-hexylthio)thiophenes] (PHTT), which carries the shorter side chain, exhibits a higher solubility in common organic solvents and is more thermally stable than the polymers with the longer dodecylthio poly[(3-dodecylthio)thiophenes] (PDDTT) chains. The polymers are moderately conductive after being doped by FeCl3 or I2. The high concentration of covalently bonded chlorine found from XPS and microanalysis and supported by 1 H NMR spectra suggests chlorination of the backbone occurred during the polymerization process. The influence of chlorination on the absorption spectra and conductivity were noted and discussed. # 2002 Elsevier Science B.V. All rights reserved.

New donor–acceptor conjugated polymers ( P1 and P2 ) containing a fused-ring dithienobenzothiadiazole ( DT - BTD building block) were synthesized by using the Stille copolymerization method. The synthesized polymers were characterized by 1 H NMR, GPC, and elemental analysis. The optical band gaps of the polymers were found to be 1.86 and 1.9 eV, respectively, as calculated from their film onset absorption edge. Upon annealing both produced a distinct shoulder peak in their film absorption spectra. The electrochemical studies of P1 and P2 revealed that the HOMO and LUMO energy levels of the polymer were −5.3, −5.1 eV, and −3.4, −3.2 eV, respectively. The polymers are thermally stable up to 250–350 °C.

A series of meta -substituted polyaniline derivatives, poly[3-(ω-hydroxyhexoxy)aniline], poly[3-(ω-hydroxyoctoxy)aniline], poly[3-(ω-hydroxydecoxy)aniline] and poly[3-(ω-hydroxydodecoxy)aniline] have been synthesized via chemical oxidative polymerization. The resulting polymers show enhanced solubility in organic solvent. The polymerization yield is increased and the reaction is accelerated by the addition of aniline. The homopolymers can attain conductivity in the range of 10 −6 to 10 −4 S cm −1 after protonic doping with HCl. Upon doping oxidatively with iodine, the conductivity is ca. 10 −5 to 10 −3 S cm −1 . For the copolymers with aniline (15 mol%), the corresponding conductivity is higher, 10 −5 to 10 −3 S cm −1 upon HCl doping and 10 −4 to 10 −2 S cm −1 upon iodine doping. Thermogravimetry (TG) of the polymer depicts two major weight loss steps corresponding to the degradation of side chain and the thermal breakdown of the backbone, respectively. The polymers are largely amorphous but show an increase in crystallinity with increasing pendant chain length. The polymers were also subjected to FT-IR, UV–VIS and X-ray photoelectron spectroscopy (XPS) studies.

A novel series of poly(2,5-dialkoxy-1,4-phenylene-alt-2,5-pyridine)s functionalized with alternating donor/acceptor repeat units was synthesized using a Suzuki coupling approach and characterized by FT-IR, NMR (13C and 1H), UV−vis, fluorescence spectroscopy, gel permeation chromatography, and thermal analyses. The derived polymers were soluble in common organic solvents and trifloroacetic acid and exhibited good thermal stability. In all cases, the electronic and optical properties of these novel copolymers were consistent with the rigid-rod conjugated structure. They emitted intense blue light under UV irradiation in both the film and solution phases with high quantum yields. Single-layer blue light-emitting diodes were successfully fabricated using these materials as emitting layers. The electrochemical behavior of these new polymers depicted facile n-doping and good electron transporting properties attributable to the presence of the electron-withdrawing pyridinyl unit. These polymers displayed bathoch...

A series of polymers comprising alternating phenylene and thienylene repeating units and with electron-donating or -withdrawing groups attached on thienylene units, i.e., poly[1,4-bis(3-X-2,5-thienylene)phenylene-alt-2,5-dioctyl-1,4-phenylene] (PBTX, X = OMe, H, Cl, Br, CN), has been synthesized and characterized. These polymers are highly fluorescent, among which PBTH shows the highest solution quantum yield, up to 94% relative to quinine sulfate. The absorption and emission peak wavelengths of PBTOMe are bathochromically shifted and band gap (Eg) is lowered by the presence of electron-donating OMe group, in comparison with PBTH. The influence of electron-withdrawing groups, Br, Cl, and CN, on the absorption peak wavelength and Eg, on the other hand, is not so great. Nevertheless, the film of PBTCN shows an emission maximum near to that of PBTOMe due to the strong interchain interactions. The band structures as deduced from electrochemistry give information supporting the optical measurements. The IP of ...

The electrochemical and optical properties of poly(3-substituted-2,2'-bithiophene)s with bromo, alkyl, alkoxy and alkylthio pendants obtained by electrochemical polymerisation were investigated. As 3-alkylthiothiophenes, 3-alkylthio-2,2'-bithiophenes cannot be electropolymerised although the polymer can be successfully generated via a chemical oxidative approach. Other monomers were successfully electropolymerised to afford uniform polymer films on the anodic electrodes by adopting either Bu 4 NBF 4 -CH 3 CN or boron trifluoride diethyl etherate (BF 3 -OET 2 ) as the electrolytic media. These two media exhibit contrasting effects on the film formation behaviour and optoelectronic properties in some of these polybithiophenes with differen pendants. The oxidation potentials of monomers in Bu 4 NBF 4 -CH 3 N follow the trend: 3-methoxy-2,2'-bithiophenes < 3-octylthio-2,2'-bithiophenes < 2,2'-bithiophenes < 3 octyl-2,2'-bithiophenes < 3-bromo-2,2'-bithiophenes while those of the polymers are poly(3-methoxy-2,2'-bithiophene)s < poly(3-octyl-2,2'-bithiophene)s < poly(2,2'-bithiophene)s < poly(3-bromo-2,2'-bithiophene)s. However, in BF 3 OEt 2 the tend of oxidation potentials for monomers is 3-octylthio-2,2'-bithiophenes < 2,2'-bithiophenes < 3-bromo-2,2'-bithiophenes < 3-octyl-2,2'-bithiophenes < 3-methoxy-2,2'-bithiophenes while that for polymers is poly(3-octyl-2,2'-bithiophenes) < poly(3-methoxy-2,2'-bithiophenes) < poly(2,2'-bithiophenes) < poly (3-bromo-2,2'-bithiophenes). The facile and stable p- and n-dopability of poly(3-alkyl-2,2'-bithiophene) was also investigated.

The synthesis and electropolymerization of 3-alkylthiophenes functionalized with a terminal amino group and its protected forms are reported. As expected, due to the strong electronic interference of the amino group, the electropolymerization of the unprotected monomer is fully inhibited. After protection of the amino group the polymerizability of the corresponding monomers is considerably improved; however, the successful polymerization process clearly depends on the nature of the used protective group. Only such monomers in which the nucleophilic character of the amino group is strongly suppressed by a suitable proctective group undergo electropolymerization to form the corresponding electroactive polymers. The obtained polymers are electrochemically stable and, besides the typical properties such as redox behavior and electrochromism, they exhibit a distinct solvatochromic behavior. Electrical conductivity measurements on their oxidized forms by means of the two-probe method give values in the range of 10 -3 to 10 -2 S . cm -1 . The feasibility of using the resulting polymers as conducting carrier materials was demonstrated by the removal of the protecting groups and the subsequent attachment of a redox active ferrocene compound. Electrochemical and spectroscopic experiments confirmed that after the polymer analogous reaction the used redox active ferrocene model compound is covalently immobilized onto the polymer surface and the electroactivity of the bonded redox groups as well as the carrier materials is retained.

Two novel thiophene derivatives, 3,3-dithiobis(2,2'-bithiophene) and 3',3'-dihexyl-3,3-dithiobis(2,2'-bithiophene), which have two 2,2'-bithiophene units linked by -S-S-bond in the 3-positions were synthesized and polymerized by chemical oxidation with FeCl 3 . These novel cross-linked electroactive polymers attained electrical conductivity of 0.04 S. cm -1 upon doping with iodine and displayed good thermal stability in both their doped and dedoped state. Electrochemical polymerization of 3,3-dithiobis(2,2'-bithiophene) afforded uniform films with a high degree of conjugation exhibiting reversible electrochemical redox recycability.

Of the numerous thiophene derivatives, 3-alkylsulfanylthiophenes (3AST) is one of the few that cannot be readily polymerized electrochemically to afford the corresponding conductive polymer films. We demonstrate in this paper that 3,3‘-dialkylsulfanyl-2,2‘-bithiophenes are appropriate monomers into polythiophenes incorporating pendant alkylsulfanyl moieties. Facile electrochemical polymerization can be effected by both the potentiostatic and galvatiostatic approach. The resulting polymer films have molecular weighs (Mn) of ca. 3600 and were soluble in common solvents. Characterization by NMR, UV−vis spectroscopy, cyclic voltammetry, and X-ray photoelectron spectroscopy are described. The polymers depicted a low-energy π−π* transition despite the high steric effects present in such HH−TT polythiophenes. In direct contrast to poly[3,3‘-dialkyl-2,2‘-bithiophene]s and poly[3,3‘-dialkoxy-2,2‘-bithiophene]s, PDASBTs exhibited significant thermochromistic effects. More significantly, the polymer films exhibited ...

A novel series of functionalized polythiophenes incorporating 3-(ω-bromoalkyl) pendants were synthesized by chemical oxidative polymerization using FeCl 3 and characterized using FT-IR, UV–Vis absorption spectroscopy, fluorescence emission spectroscopy, conductivity measurements and thermal analyses. These polymers attained a maximum electrical conductivity between 4.7 and 8.4 S cm −1 upon doping with iodine and have a fluorescence quantum yield of up to 11.1% with respect to quinine sulfate. The influence of the terminal ω-bromine substituent as of the length of the alkyl pendant on electrical conductivity, spectral behavior and thermal stability is discussed.

A novel regioregular polymer comprising alternating 1,4-phenylene and 3-butyl-2,5-thienylene repeat units has been synthesized and characterized using 1 H NMR, FTIR, UV-VIS absorption and fluorescence emission spectroscopy. The derived polymer showed strong fluorescence with a solution quantum yield of 48% relative to quinine sulfate and a film phase photoluminescence yield of 17%. Green light-emitting diodes were fabricated using the polymer as the emitter layer.

A series of alternating block copolymers incorporating 3-alkyl-substituted thiophene and aniline repeat units (PATBAs): poly{4-[2-(3-methyl)thienyl]benzenamine} (PMTBA), poly{4-[2-(3-butyl)thienyl]benzenamine} (PBTBA), poly{4-[2-(3-octyl)thienyl]benzenamine} (POTBA) and poly{4-[2-(3-dodecyl)thienyl]benzenamine} (PDTBA) were synthesized via chemical oxidative polymerization using ferric chloride as oxidant. The resulting polymers were characterized by FT-IR, UV-Vis, fluorescence spectroscopy, elemental analysis, thermogravimetry and electrical conductivity measurements. It was shown that coupling during polymerization occurred through the α-position of the thienylene ring and the amino moiety. Upon doping with iodine the polymers attained electrical conductivity ranging from 10−4 to over 10−3 S cm−1. The fluorescence quantum efficiency of the polymers in solution was found to decrease with increasing pendant alkyl-chain length. Scanning electron microscopy (SEM) revealed a globular morphology similar to poly[4-(2-thienyl)benzenamine] and polythiophene.

A series of poly[3,3′-dialkyl-2,2′-(ethyne-1,2-diyl)bis(thiophene)]s, comprising a rigid carbon-carbon triple bond between two bithiophene repeating units, were synthesized. The improved rigidity of the polymer backbone led to an increased fluorescent quantum yield in comparison to poly(3-alkylthiophene)s. A generic trend depicting decreasing Stokes shift in the fluorescence spectra with increasing pendant alkyl chain length was observed. The incorporation of the acetylenic spacer also resulted in a significant red shift in the absorption spectra in comparison to poly(3-alkylthiophene)s, corresponding to an increase in effective conjugation over the entire series of polymers. These polymers, upon doping with iodine or ferric chloride, gave electrical conductivity in the range of 10 0 to 10 –4 S cm –1 . Thermochromism studies showed a blue shift in absorption peak as the temperature changes from 25 to 180°C. The influence of alkyl chain length and the acetylenic spacer on the conductivity and UV-VIS absorption is also discussed. In situ electrochemical doping studies were monitored using UV-VIS-near infrared absorption spectroscopy and showed the evolution of polaron bands at around 1.4 eV.

Pyrrole and 3-alkylpyrroles were grafted via chemical oxidative polymerisation with FeCl 3 to copolymers of methyl methacrylate and ω-(N-pyrrolyl)alkyl methacrylates incorporating varying amounts of ω-(N-pyrrolyl)alkyl methacrylates with varying alkyl chain lengths. The electrical conductivity of the resultant graft copolymers attained 10 –4 -10 –3 S cm – , with the length of the alkyl spacers in ω-(N-pyrrolyl)alkyl methacrylates having little influence on the conductivity. A longer alkyl spacer, however, resulted in a lower glass transition temperature for the resulting graft copolymers. The graft copolymers from pyrrole were insoluble whilst those arising from 3-alkylpyrroles were completely soluble in common organic solvents even in their doped states.

The oxidative polymerisation of o- and m-aminobenzenesulfonic acid has been achieved for the first time at high pressures to yield fully sulfonated polyaniline (SPANI) which is self-doping, water soluble and electrically conducting.

A series of polymers containing alternating phenylene and symmetrically substituted bithiophene repeat units have been synthesized and characterized using UV-Vis absorption spectroscopy, fluorescence emission spectroscopy, conductivity measurement and thermal analyses. The results reveal that the polymers have a bandgap energy of 2.5 eV and a fluorescence quantum yield of up to 26% with respect to quinine sulfate. The polymers show a maximum conductivity of 0.2 S cm −1 upon doping with I 2 and display good thermal stability in both neutral and doped states. The influence of alkyl chain size on conductivity, spectral behavior and thermal stability is discussed.

Homopolymer of the symmetrical 3,3′-dibutylsulfanyl-2,2′-bithiophene (DBSBT) and copolymer of DBSBT with thiophene or bithiophene were prepared by nickel-catalyzed Grignard cross-coupling polymerization. These new solvent-processible regioregular copolymers have UV absorption maxima at about 500 nm in deposited film with a bandgap of 1.7–1.8 eV. They were readily doped by iodine and FeCl 3 to an electrical conductivity of 10 −3 –10 −2 S cm −1 . The polymers were characterized by FT-IR, NMR, X-ray photoelectron spectroscopy (XPS) spectra and cyclic voltammetry.

A series of 1, 2-heteroarylethynes which are potential monomers to low bandgap materials were synthesized and their He I photoelectron spectra measured and assigned with the aid of empirical arguments and semi-empirical MO calculations. The electronic structure analysis reveals that C equivalent to C bond is an efficient ''relay'' of pi-electrons and that it supports inter-ring conjugation. The efficiency depends on the nature of ring heteroatom, but not on its position within the ring. The importance of C equivalent to C bond relay is discussed in the broader context of conjugated polymer applications.

A series of poly[3-(ω-hydroxyalkyl)thiophenes] was synthesized by chemical oxidative polymerization using FeCl 3 and characterized by FT-IR, thermal gravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). Upon doping with iodine the polymers attained electrical conductivities of between 0.5 and 38 S cm −1 . Electrical conductivities of doped samples were found to increase with alkyl chain lengths, being optimum for the octyl pendant moiety. Thereafter, the conductivity decreased, as the doping and dedoping for the polymers became more difficult. Increasing the hydrocarbon chain length of the pendant substituent also resulted in decreased thermal stability of the polymers. XPS results showed that some C–OH groups in the polymers were oxidized to CO in the polymerization process.

Polymerization of methyl methacrylate (MMA) has been studied in ternary microemulsions which were stabilized by tetradecyltrimethylammonium bromide (TTAB) or stearyltrimethylammonium chloride (STAC). The sizes of MMA-swollen polymer particles (Rh) increased continuously during polymerization. This is in contrast to that of the styrene system, where Rh increased very rapidly to a maximum and then decreased continuously towards a constant value. The continuous growth of PMMA particles at 60°C are discussed. The stability of PMMA latexes increased with increasing the hydrophobic chain length of the cationic surfactant used. Traces of the coagulations of PMMA particles in the TTAB system can be seen from TEM. © 1995 John Wiley & Sons, Inc.

Poly(4-aminobiphenyl) synthesized both chemically and electrochemically were examined and compared by UV, FT-IR, X-ray photoelectron spectroscopy, thermogravimetry and differential scanning calorimetry. Results indicate that, in chemically synthesized samples, protonation of the nitrogen atoms occurs with chloride as the major counter ion, whilst, in the electropolymerized sample, concurrent oxidation of the biphenyl backbone was also observed. Conductivities of the electropolymerized and chemically synthesized polymers doped with FeCl 3 are 0.02 and 10 −6 S cm −1 , respectively. In addition, the chemically synthesized polymer in its base form is found to be dopable with iodine to a conductivity of 2 × 10 −4 S cm −1 . Scanning electron microscopy indicates a fibrous structure for the electropolymerized sample in contrast to the chemically synthesized form which has a granular to globular morphology, with the granules themselves made up of a fine network of fibrils.

Highly conducting polyanilines (PANI) with thermal stabilities superior to that of polyaniline doped with HCl (PANI-HCl) have been prepared by postsynthesis treatment of the PANI-base with three different phosphonic acids, R-PA, where R=butyl (Bu), decyl (Dc), and benzyl (Bn). XPS results indicate the occurrence of free dopant molecules in the sample matrix, partial segregation of dopant species to the polymer surface, and participation of H 3 O + as counter charges to some of the dopant anions in these samples. IR data suggest minimal perturbation of the PANI vibrational states when Cl - is replaced by RPO 2 (OH)

The thermal characteristics of polyaniline (PANI), poly(o-aminobenzoic acid) (POABAC) and poly(o-aminobenzyl alcohol) (POABOL) are determined and compared by thermogravimetry (TG) and differential scanning calorimetry (DSC). The higher thermal stability of POABOL is attributed to heat-induced condensation between the polymer chains. The DSC results suggest both intra- and inter-molecular interaction in the form of hydrogen bonding due to the substituent group in POABAC and POABOL. These interactions, however, occur mainly in the doped from and is greatly reduced when the dopant is expelled from the system at higher temperatures.

The unusual electrical and optical properties of polythiophenes have stimulated intense interdisciplinary research towards development of new materials over the past fifteen years. Numerous structural types within the thiophene family [1-10] have been investigated with a view to modify the electronic properties and improve the environmental stability and processibility of these materials. Arising from our ongoing interests in functionalized 2,2'biothiophenes and the resulting polymers [11-13], we investigated the synthesis and polymerization of 3,3-disulphidobis(2,2'-biothiophene) (I) which has a disulphido linkage bridging the two 2,2'-biothiophene moieties.

A novel silicon-containing copolymer with an alternating structure, poly[(5-decyldimethylsilyl-1,3-phenylenevinylene)-alt-(2,5-didodecyloxy-1,4-phenylenevinylene)], is synthesized through the Wittig reaction. The polymer is a promising green-blue emissive material for light-emitting device application due to its good solubility, high thermal stability, and intense photoluminescence.

Novel and stable electroactive polymer films which can undergo facile electrochemical p- and n-doping are successfully prepared for the first time from the electrochemical polymerization of symmetrical 3,3′-dialkylsulfanyl-2,2′-bithiophenes with long pendant chains.