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.

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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Thionyl chloride and phenyl chlorosulphinate have been shown to be useful activators for dimethyl sulphoxide in the selective preparation of ortho-methylthiomethylphenol via a [2,3]sigmatropic rearrangement. By this process, ortho-methylthiomethylated phenols having a variety of 2or 4substituents (Me, CI, OMe, NOz, and C0,Me) have been prepared in good yields. In contrast, similar reactions of 3-substituted phenols were affected by the electronic characters of the substituents. With more electron-donating groups such as OH and OMe in the 3-position, none of the expected products were obtained, but in the case of other 3-substituted phenols, two possible rearrangement products were obtained in moderate yields. o-Alkylphenols are useful intermediates in organic synthesesand there are many methods ' for the alkylation of phenol nuclei.In most cases, however, the products are mixtures of o-and psubstituted and polysubstituted phenols. The most effective procedure for selective ortho-alkylation of phenols seems to be that which involves a [2,3]sigmatropic rearrangement of a sulphonium ylide (4), the latter being generated oia abstraction of a proton from a sulphonium salt (3).

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