Detection of End Groups in Polymer Molecules

THE radical theory of vinyl polymerization is confirmed by the identification of so-called catalyst fragments in the polymer molecule. The usual method is to purify the polymer by repeated reprecipitation and to use a catalyst containing an easily identifiable element. Thus when tribromobenzoyl peroxide has been used as the catalyst and the molecular weight of the product is not too high, it is possible to identify bromine in the polymer after repeated purification¹.