Effect of glass transition on conductivity of neutral poly(3‐alkylthiophene)s

Chen, Show‐An; Ni, Jui-Ming

doi:10.1002/marc.1992.030130106

Cited by 18 publications

(3 citation statements)

References 10 publications

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“…The retention of the original absorption maximum (at 535 nm) up to 140 °C is rather unusual, which was not observed for P30T, for which a thermochromism (resulting from a rod-to-coil transition due to a melting of the ordered phase) occurs in the range of about 100-150 °C. [19][20][21] This means that no main-chain melting occurs before cracking of the side chains. Thus, a very strong mutual interaction between the neighboring side chains might exist, which prevents the main chains in the ordered phase from melting at the elevated temperature.…”

Section: Resultsmentioning

confidence: 99%

“…[5][6][7][8][9][10][11][12] Incorporation of an alkoxy group with carbon number varying from 1 to 15 on the 3-position of the thiophene ring gives polymers with an optical absorption maximum at 475-530 nm comparable with those of P3ATs but with a lower conductivity of about KH-10-2 S/cm after electrochemical doping due to lower molecular weight (MW) and with a lower oxidation potential due to electrondonating characteristics of the oxygen. [6][7][8] The polymers are soluble in organic solvents even after doping up to 20 %. Further substitution on the 4-position with a methyl group leads to an improved conductivity of about S/cm after electrochemical doping and an increased wavelength of the optical absorption maximum of about 530-550 nm.…”

Section: Introductionmentioning

confidence: 99%

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Structure/properties of conjugated conductive polymers. 2. 3-Ether-substituted polythiophenes and poly(4-methylthiophenes)

Chen¹,

Tsai²

1993

Macromolecules

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Two series of 3-substituted polythiophenes (PTs) and poly(4-methylthiophene)~ (P4MTs) having the Substituents containing 8 atoms in the backbone with oxygen as the first atom bonded to the thiophene ring, C,H&-, C~HBOC~H~O-, and CH30C2H~OC2H~O-for the former series and having the first two substituents for the latter series were synthesized by chemical polymerization using ferric chloride as the oxidizing agent and characterized using thermal analysis, various spectroscopic methods, cyclic voltammetry, and conductivity measurement. For the first series, in comparison with poly(3-octylthiophene) (P30T; A, , = 480 nm), a replacement of the first carbon attached to the thiophene ring by an oxygen atom leads to a decreased band gap ( A, = 580 nm) due to the electron-donating nature of the oxygen. Further substitution on the 4-position of the thiophene ring with the methyl group of the 3-substituted PT with the substituent C,H&-leads to an increase in the band gap due to a decrease in conjugation caused by a steric hindrance of the methyl group as reflected in the change of A, , from 580 to 420 nm. But ita oxidation potential (0.76 V) ia lower than that of P30T (1.01 V) due to electron donation to the ?r system by the oxygen. Additional replacement of the third carbon atom by an oxygen atom in the side chain (giving CdHsOC2H40-) improves the conjugation (as reflected by an increase in A, , to 530 nm and a decrease in the oxidation potential to 0.6 V) due to a strong interaction between neighboring side chains, such that no thermochromism is observed before a decomposition of side chains.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Structure/properties of conjugated conductive polymers. 2. 3-Ether-substituted polythiophenes and poly(4-methylthiophenes)

Chen¹,

Tsai²

1993

Macromolecules

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“…Note that the 7\(C) data (as well as Tip(H)) reflect the side-chain relaxation of POT, whereas the DMTA measurements (Figure 3) probe the main-chain relaxation observed at 284 K. Chen and Ni report a value of206 K for the side-chain relaxation in POT from DMTA measurements at 1 Hz. 29 In the present DMTA investigations this low-temperature region was not investigated since the sub-Tg transition is too weak to be observed in the blends at low POT concentrations. Tx(C) data for POT, PPO, and their blends are shown in Figure 9 and Table IV.…”

Section: Table II Proton Ti(h) Valuesmentioning

confidence: 95%

Structure and dynamics in polymer blends: a carbon-13 CPMAS NMR study of poly(3-octylthiophene)/poly(phenylene oxide)

Schantz¹,

Ljungqvist²

1993

Macromolecules

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We report 13C CPMAS (cross-polarization magic angle spinning) NMR results from meltmixed blends of undoped poly(3-octylthiophene) (POT) and poly(phenylene oxide) (PPO). The behavior of proton spin-lattice relaxation times in the rotating frame (7\P(H)) and laboratory frame (Ti(H)) indicate that the blends are immiscible. Alkyl side-chain 13C spin-lattice relaxation times (7i(C)) increase considerably in blends of POT concentrations lower than ~30%, reflecting an increased molecular flexibility for POT. Changes in mobility are indicated also from dynamic mechanical measurements in which the maximum of the loss tangent for POT is found to shift to lower temperatures in the blends by ~5-15 K. We suggest that the increased mobility is caused by thermal stresses in the material.

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Raman spectroscopic studies on the structural changes of electrosynthesized polypyrrole films during heating and cooling processes

Feng-En

Zhang

Wang

et al. 2003

J of Applied Polymer Sci

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Polypyrrole films were electrochemically synthesized by direct oxidative polymerization of pyrrole in acetonitrile containing ␤-naphthalene sulfonic acid or tetrabutylammonium tetrafluoroborate as an supporting electrolyte. We characterized the as-grown polypyrrole films by resonance Raman spectroscopy in the temperature region of Ϫ195 to 275°C. During the heating process, the Raman bands related to the oxidized species decreased gradually, due mainly to the affect of oxygen and moisture in the air, and, finally, the neutral polymer chains decomposed into disordered carbons. During the cooling process, polymer chains changed from disordered (coil-like) to ordered (rodlike) structures and caused the elongation of the conjugated chain length. This results in a red shift of the absorption of the electron spectra of the polymer and the enhancements of the Raman bands related to the oxidized species.

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Effect of glass transition on conductivity of neutral poly(3‐alkylthiophene)s

Cited by 18 publications

References 10 publications

Structure/properties of conjugated conductive polymers. 2. 3-Ether-substituted polythiophenes and poly(4-methylthiophenes)

Structure/properties of conjugated conductive polymers. 2. 3-Ether-substituted polythiophenes and poly(4-methylthiophenes)

Structure and dynamics in polymer blends: a carbon-13 CPMAS NMR study of poly(3-octylthiophene)/poly(phenylene oxide)

Raman spectroscopic studies on the structural changes of electrosynthesized polypyrrole films during heating and cooling processes

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