Binary copolymerization according to the terminal model

If chains are long such that the initiation and termination reactions have a negligible effect on the average sequence distribution, then according to the terminal model, PAA, the probability that a chain ending in monomer unit MA adds another unit MA, is given by eq. 22 8 

The probability of a given sequence is the product of the probabilities of Lhe individual steps that give rise to that sequence. Thus, the fraction of isolated sequences of monomer MA which are of length n is  

Expressions for the dyad, triad and higher order n-ad fractions can also be derived in terms of these probabilities. Thus the dyad fractions are given by eqs. 25-27. 

The mirror image sequences, such as the AB and BA dyads, cannot be distinguished. 

With lhe penultimate model, the probability that a chain with a terminal MBA 

---