Polymerization of a-Methylstyrene by Means of Ziegler Catalyst and the Properties of Polymers Obtained

IV. Properties of Poly-α-Methylstyrene Prepared with Various Catalysts

Abstract

Properties of poly-α-methylstyrene by AlEt₃-TiCl₄ at -78°C were compared from the standpoint of the stereoregularity with those of poly-a-methylstyrene by BF₃·EOEt₂ and TiCl₄at -78°C, and by metallic Na and K at room temperature. Since crystallization of these polymers is very difficult, glass transition temperature, infrared absorption spectrum, density and solubility were measured in amorphous state. Some differences depending on the polymerization conditions were observed in glass transition temperature and infrared spectrum. The glass transition temperature of the polymer prepared with AlEt₃-TiCl₄ catalyst is 117°C, and that of the polymer prepared with metallic K catalyst is 107°C.(The degree of polymerization of both polymers is ca. 3000) The intensity of absorption peak at 885 cm^-1 in the infrared absorption spectrum is affected by the polymerization conditions. These differences may result from differences in the stereoregularity of the polymer. The density is 1.0610±0.0005 independent of polymerization conditions. However, when the polymer is heated above the glass transition temperature, it changes to 1.0630±0.0005. The solubility in methyl ethyl ketone depends on the polymerization conditions, but the relationship between the solubility and the stereoregularity of the polymer is not clear. The following shows the order of catalyst activity defined by the stereoregularity estimated from the results of glass transition temperature and infrared spectrum.
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“The stereoregularity ” used here may mean “the isotacticity.”