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The structure formation in solvent cast stereoregular isotactic poly(acrylonitrile) (PAN) film was discussed in comparison with that of an atactic one. The film was prepared by solvent-casting method from various organic solvents including N,N-dimethylformamide (DMF). It is shown that there exist at least two different molecular cohesion states (type I, II), which can be detected by WAXD (Fig. 1). The former (type I) showed sharp two rings resembling to that of the original powder sample, while the latter (type II) did many co-axial rings suggesting the sample is partially crystallized. The latter structure was strongly dependent on the extent of isotacticity (PAN), the kind of solvents (LIQUID), and experimental factors (CONDITIONS). These factors were studied in detail in connection with the film preparation process. [ABSTRACT FROM AUTHOR]

A novel synthesis of stereoblock copolymer containing highly isotactic acrylonitrile (AN) sequences in its polymer backbone was reported. That is, γ-irradition post-polymerization of AN/urea canal in the solid state was a typical living radical system, as evidenced by various modified experiments. After finishing the polymerization, freshly distilled α-chloroacrylonitrile (CAN) was introduced with methanol, and the mixture was allowed to copolymerize at low temperatures. The content of PCAN component introduced in this way was estimated to be about 23%mol by a calibration curve. When the sample was heated under mild heating conditions (under vacuum, at 80°C, for overnight), color changed from white to pale pink to bright purple with maintaining the solubility into DMF, etc. UV spectra indicate that the several peaks appeared in a longer wave length (400~650nm), which was explained in terms of the formation of conjugated double bonds -(CH=CH(CN))n-on a polymer backbone via elimination (HCl). The length (n) of the conjugated double bond was estimated to be about 20-25 numbers in one typical case. Under severe oxidative-heating conditions, however, the powder lost the solubility with accompanying the color change to reddish brown. A useful candidate for the precursor of super-conducting material, isotactic PAN and atactic PCAN stereoblock sequences on its backbone, was prepared in this way. [ABSTRACT FROM AUTHOR]

An abstract of the conference paper "Melting Temperature for Single Crystals of Stereoregular Isotactic Poly(acrylonitrile) Prepared by Isothermal Solution Crystallization From Different Organic Solvents," by Masatomo Minagawa and colleagues, is presented.

The solvent properties of ZnCl2 solution toward isotactic poly(acrylonitrile) (PAN) were studied by using a laser-optical instrument, FT-IR and Raman spectroscopy. This solvent showed an excellent solubility toward isotactic PAN. The best salt concentration for wet spinning was in a quite narrow salt range (56-60wt%), however. In the inverse plots of dissolution temperature (Tsol) against the isotacticity, a breaking point appeared, which was connected to the existence of two different dissolution mechanisms. This breaking point did not appear for organic polar solvents, such as N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). An extraordinarily large shift of the CN band to a higher frequency (2249→2276cm-1) in FT-IR spectra was observed, which was explained in terms of the coordination bonding of ZnCl2 toward CN groups. The significance of the coordination number (n) of H2O molecules around a ZnCl2 molecule was suggested from both a numerical calculation and CN band shift. Physical meaning of Tsol master curve, which appeared in the plots of Tsol against isotacticity as a function of salt concentration, was discussed in relation to the derivation of dissolution criterion of isotactic PAN in this solvent. [ABSTRACT FROM AUTHOR]