A study of hydrogen chloride evolution versus time curves for polysulphonylations, conducted in the presence of excesses of sulphonyl chloride groups, shows that chain branching proceeds very much more slowly than chain extension, but that branching occurs to a greater extent in reaction (iii) than in reactions (i) and (ii). The proportion of linear repeat units, I and II, and branch point units, III, are estimated by analysis of the hydrogen chloride evolution curves, and/or by an n.m.r. technique involving spectrum accumulation. The results show that high polymers obtained from reaction (iii) contain the units I, II and III in the approximate percentage proportions 90 : 10 : 1·6 respectively, while the polymers from reactions (i) and (ii) consist essentially of unit I (ca. 99 per cent) and contain less than 0·7 per cent of the branch point units, III. © 1968.
