USE OF CHAIN-LENGTH DISTRIBUTIONS IN DETERMINING CHAIN TRANSFER CONSTANTS AND TERMINATION MECHANISMS

A new method for determining transfer constants based on an analysis o f the In chain length (Or molecular weight) distributions has recently been reported. In this paper, the basis of this method is examined in terms of classical statistics and with the aid of simulated chain len gth distributions. The advantages, limitations and sources of error in the method are considered with reference to conventional analysis. We show that one major benefit is that the requisite information can be obtained by analysis of a small segment of the chain length distributi on. This means that it may be applied under circumstances where there may be overlap between the distributions of the new polymer being form ed and the transfer agent (i.e. transfer constants to polymeric specie s can be determined). The method also has general application since it is less sensitive to experimental noise, poor baseline selection, or the presence of artifacts in gel permeation chromatograms. Finally we look at the scope for obtaining additional mechanistic information on termination mechanisms by analysis of chain length distributions of lo w-conversion polymers by considering the effects of combination:dispro portionation ratios and chain length dependent propagation and termina tion.