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Results of light scattering as well as viscosity measurements on a series of isotactic polystyrene fractions, and on a sample of unfractionated isotactic polymer in toluene at 30°C. are reported. The results are in agreement with the conclusion of Natta, Danusso, and Moraglio that no difference exists between the viscometric behavior of atactic and isotactic polystyrene; the same seems to hold also for the molecular dimensions. The ratio A2M/[η] for isotactic polystyrene is lower than for atactic fractions, and according to the results of Danusso and Moraglio, the second virial coefficient, A2, is probably responsible for the observed difference. The data obtained with the unfractionated sample can be explained in terms of an unusually high M̄w/M̄n ratio.

It has already been shown that many pure metals, as evaporated metal films, are suitable catalysts in giving polyethylidene from the decomposition of diazoethane in ethereal solution, whilst other metals (for instance Ag and Pd), although decomposing diazoethane, do not give polymer. The composition of the gases evolved during the reaction, as obtained by gas chromatographic analyses, is different in the two cases: besides nitrogen the 2‐butenes represent the main fraction of the gases evolved when polymer formation occurs; ethylene when no polymer is formed is the most important fraction of the light hydrocarbons evolved. A mechanism for the reaction of polymer formation from diazoethane is proposed, as derived from the results reported here.

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