The present paper describes the preparation and characterization of stable aqueous dispersions of poly (3-hexylthiophene) (P3HT) by a precipitation method. P3HT was first synthesized by oxidative polymerization of 3HT with iron(III) chloride as an oxidant. Number-average molecular weight (M n ) of P3HT increased with an increase in 3HT concentration. Colloidal particles were prepared by adding a tetrahydrofuran (THF) solution of P3HT into a large amount of distilled water. TEM observations showed that the particle size increased with an increase in the concentration and M n of P3HT. The size of the particles was in the range of 50 to 600 nm. The spectral features of the aqueous dispersions were investigated by means of UV-vis spectroscopy. P3HT provided the -Ã absorption band at 436 nm in THF. On the other hand, the dispersions brought about a bathochromic shift of the bands and a larger red shift was observed as the polymer concentration became higher, indicating that P3HT would take a well-stacked structure in the particles. Temperature dependence of UV-vis absorption spectra for P3HT aqueous dispersions was also studied in the temperature range of 0 to 80 C, which revealed that P3HT in the dispersed state showed a thermochromism similar to that of P3HT in THF.KEY WORDS: Polythiophene / -Conjugated Polymer / Poly(3-hexylthiophene) / Colloidal Particle / Conducting Polymer / Precipitation Method / Thermochromism / Poly(3-hexylthiophene) (P3HT) is a subject of extensive study because of its solubility, fusibility, and environmental stability.1 P3HT also exhibits unique properties such as thermochromism and solvatochromism. [2][3][4][5][6] This functional polymer is viewed as potentially useful materials in fieldeffect transistors, optical and electronic sensors, light-emitting devices, nonlinear optical materials, etc. 7-9Our attention has focused on colloidal dispersions of P3HT particles. Colloidal particles are of great importance due to their interesting physical properties as well as their potential technological applications.10,11 Several attempts have been made so far to produce P3HT particles. Yamamoto et al. employed a reprecipitation method to prepare colloidal dispersions of P3HT. Methanol, which is a poor solvent for P3HT, was added to the CHCl 3 solution of P3HT, resulting in the formation of P3HT particles. 12,13 Takeuchi and Kobashi also investigated in detail the kinds of poor solvents and clarified the precipitation conditions for improved yields. 14 Furthermore, it has been reported that the use of a nonionic surfactant, Tween 80, provided stable aqueous dispersions of P3HT. 15To our knowledge, few reports on water self-dispersible P3HT particles have been published. 15 There is hence a lack of information about colloidal properties of P3HT water dispersions, such as particle size, particle morphology, optical property, etc. Development and characterization of such dispersions are of great significance from an environmental as well as industrial aspect. The purpose of the present study is to de...
Poly(vinylidene fluoride) (PVdF) converts easily to thermally reversible gel at room temperature in aliphatic ketones or cyclic ketones such as 3-pentanone, 3-hexanone, cyclohexanone, and g-butyrolactone, etc. Gelation of PVdF in these ketones took place through crystallization of polymers from solution. The crystallization process was investigated in detail by Fourier transform infrared (FTIR) measurements. The FTIR spectra were recorded continuously at room temperature until the solution converted to gel. It was suggested from spectral data that polymer chains packed together (i.e., crystallization took place) into the TTTGTTTG V conformation in the case of PVdF/ g-butyrolactone solution, followed immediately by gelation. On the other hand, crystallization occurred into the TGTG V conformation in the case of other ketones and gelation immediately took place. Melting temperatures T g m of PVdF gels thus prepared from these solvents were measured. T g m showed a solvent dependence.
Recent efforts have focused on the use of sericin proteins extracted from cocoons of silkworm as a healthy food source for human consumption. In this study, we focused on the antioxidative properties of sericin proteins. The antioxidative properties were measured in sericin proteins extracted from the shell of the cocoon, designated hereafter as white sericin protein and yellow-green sericin protein, as well as bread without sericin protein and bread to which white sericin powder had been added using four measurement methods: 1,1-Diphenyl-2-picrylhydrazyl (DPPH), chemiluminescence, oxygen radical absorbance capacity (ORAC) and electron spin resonance (ESR). High antioxidative properties of sericin proteins were indicated by all four methods. A comparison of the two types of sericin proteins revealed that yellow-green sericin protein exhibited high antioxidative properties as indicated by the DPPH, chemiluminescence and ORAC methods. By contrast, a higher antioxidative property was determined in white sericin protein by the ESR method. Consequently, our findings confirmed that sericin proteins have antioxidative properties against multiple radicals. In addition, the antioxidative property of bread was enhanced by the addition of sericin powder to the bread. Therefore, findings of this study suggest that sericin proteins may be efficiently used as beneficial food for human health.
ABSTRACT:The Flory-Huggins interaction parameter (χ 12 ) between poly(vinylidene fluoride) (PVdF) and organic solvent was estimated experimentally over wide range of temperature by an inverse gas chromatography (IGC) using many kinds of solvents such as alkane, alkene, ketone, lactone, and nitrogen-containing solvent. The thermoreversible gelation of PVdF solution was discussed from the magnitude of interaction parameter χ 12 between PVdF and solvent. The parameter χ 12 was measured for a concentrated PVdF solution by the usual IGC technique. The parameter χ 12 obtained for each PVdF/solvent system increased slowly with decreasing temperature. The present systems were divided broadly into three groups according to the magnitude of χ 12 in the vicinity of room temperature, i.e., group (a) with χ 12
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