Polymerization of 3-Hexylthiophene in the Presence of Titanium Carbide and Conductivity-Temperature Characteristics of the Conductive Composite Product.

J of Applied Polymer Sci

Shimomura

et al. 2006

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ABSTRACT:The temperature-conductivity characteristics of poly(3-hexylthiophene) (P3HT) composites filled with P3HT-grafted indium tin oxide (ITO) particles were investigated in this work. The ITO particles were first treated with a silane coupling reagent of 3-aminopropyltriethoxysilane (APS), and then thiophene rings were introduced through a condensation reaction between the ending amino groups of APS and the carboxylic groups of thiophene-3-acetic acid. The composites were prepared by the polymerization filling of the 3-hexylthiophene (3HT) monomer with the thiophenering-introduced ITO particles. Elemental analysis, Fourier transform infrared, and X-ray photoelectron spectroscopy were used to confirm the grafting reaction on the ITO surface. The longer the polymerization time was or the higher the 3HT/ITO feeding ratio was, the more P3HT was grafted. The influence of the grafted amount on the electrical properties of ITO particles was attributed to the wrapping effect formed by the grafted P3HT on the surface of the ITO particles. The conductivity change of the P3HT-grafted ITO/ P3HT composites was proved to be subject to the change in the average gap width of ITO interparticles, which was determined by the filling ratio of P3HT to ITO in the polymerization and the volume expansion effect of a P3HT thin film between neighboring ITO particles during the heating process. In comparison with the ungrafted ITO/P3HT composites, the grafting treatment enhanced the interaction between the particles and polymer matrix, and this was helpful for obtaining a more homogeneous dispersion structure for the composites and thus afforded a higher positive temperature coefficient intensity and better reproducibility.

Section: Introductionmentioning

confidence: 79%

Preparation of a poly(3‐hexylthiophene)‐grafted indium tin oxide/poly(3‐hexylthiopene) composite and its conductivity–temperature characteristics

J of Applied Polymer Sci

Shimomura

et al. 2006

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“…To improve the conductivity, different types of conducting particles (carbon black, ITO, and TiC) were introduced into the fractionated P3HT matrix, and the temperature-conductivity characteristics of the resulting mixtures were investigated. [7][8][9][10] The results demonstrated that composites of high molecu-lar weight P3HT and relatively large conducting particles (e.g., TiC) exhibited a good PTC effect near the T g temperature of P3HT. Yet the origination of the PTC effect in this case seemingly bore no relation to the conductivity decrease of the P3HT matrix caused by structural changes near the melting point.…”

Section: Introductionmentioning

confidence: 97%

“…However, low conductivity at ambient temperature (∼ 10 −8 S/cm) obviously limited its application. To improve the conductivity, different types of conducting particles (carbon black, ITO, and TiC) were introduced into the fractionated P3HT matrix, and the temperature‐conductivity characteristics of the resulting mixtures were investigated 7–10. The results demonstrated that composites of high molecular weight P3HT and relatively large conducting particles (e.g., TiC) exhibited a good PTC effect near the T g temperature of P3HT.…”

Section: Introductionmentioning

confidence: 99%

All polymer PTC devices: Temperature‐conductivity characteristics of polyisothianaphthene and poly(3‐hexylthiophene) blends

J of Applied Polymer Sci

Shimomura

et al. 2005

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ABSTRACT:The present article is concerned with the temperature-conductivity characteristics of blends consisting of polyisothianaphthene (PITN) particles and a soluble poly(3-hexylthiophene) (P3HT). PITN was synthesized by direct conversion of 1,3-dihydroisothianaphthene (DHITN) monomer using N-chlorosuccinimide (NCS) as an oxidation/dehydrogenation reagent. The high conductivity and thermal stability of the doped and dedoped PITN were confirmed. Microscopic investigation by scanning electron microscopy (SEM) showed that the as-prepared PITN exhibited diversified shapes and sizes, with large rectangular particles having an average size of 2 ϳ 5m and fine round particles ranging from 0.1 to 0.3 m. The PITN particles were blended with the chemically synthesized P3HT as a high conductivity component to improve the conductivity and simultaneously maintain the positive temperature coefficient (PTC) effect of the original P3HT near its melting point. The temperature-conductivity characteristics for PITN-P3HT blends with various PITN contents showed that a blend having both a high conductivity (nearly 3 ϳ 4 orders higher than that of the original P3HT) and a good PTC intensity could be obtained with a PITN content of 20 ϳ 25%. The different temperature-conductivity behavior of P3HT blends filled with PITN as compared to other conducting particles, for example, carbon black, was explained by its unique dispersion structure due to a relatively higher adhesive interaction of PITN particles with the P3HT matrix during the precipitation process. The results from heating recycles revealed that the PTC effect of PITN-P3HT blends was not just related to the conductivity decrease of the P3HT matrix, arising from the conformational change of the conjugated backbone during the melting, but also to the dilution effect of the conducting percolation network due to the mobility of PITN particles induced by the viscosity decrease of the P3HT matrix.

“…The composites of P3HT and conductive particles, such as P3HT‐TiC composite,9 are expected to have both PTC property and enhanced conductivity. On the other hand, there still remains a possibility to improve the conductivity of P3HT itself.…”

Section: Introductionmentioning

confidence: 99%

Temperature-conductivity characteristics of the composites consisting of fractionated poly(3-hexylthiophene) and conducting particles

Yamauchi

et al. 2000

J. Appl. Polym. Sci.

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Poly (3‐hexylthiophene) (P3HT) synthesized by oxidative polymerization was fractionated by molecular weight by using organic solvents. The fraction of higher average molecular weight gave higher regioregularity and conductivity. Composites of the P3HT fraction having the highest molecular weight were prepared by use of the following conducting particles as fillers: titanium carbide (TiC), indium tin oxide (ITO), and carbon black (CB). Temperature‐conductivity profiles of the composites showed that the resistance change with PTC (positive temperature coefficient) effect was strongly influenced by the content and size of conducting particles and the molecular weight of P3HT. Although no significant PTC effect for P3HT‐CB composite and little effect for P3HT‐ITO composite system were observed, the P3HT‐TiC composite containing TiC of 70–80 wt % showed an obvious PTC effect that brought the conductivity change by about four orders of magnitude near the glass transition temperature of P3HT. However, such a remarkable PTC effect was not observed for the P3HT‐TiC composite prepared with the P3HT fraction of low‐molecular weight. It was shown that a good PTC effect could be achieved by the composite consisting of the P3HT of high‐molecular weight and the conducting particles of relatively large size. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 3069–3076, 2000