Dyad and Triad Probabilities in Copolymer

Consider a random copolymer obtained by free radical copolymerization. The statistics of copolymerization and dyad probabilities can be calculated as follows. The propagation reactions can be of four types  

The free radical species formed may be assumed to be highly reactive and can be assumed to be consumed as rapidly as they are formed. This is referred to as the quasi-steady-state assumption (QSSA). Thus  

The dyad probabilities can be calculated from the selectivity achieved in the parallel reactions. Thus, the probability of the M,-Mi dyad can be found to be 

In a similar fashion, the M2-M2 dyad probability, P22, and M2-M1 dyad probability can be written as 

The styrene and acrylonitrile can be copolymerized by free radical methods using a continuous stirred tank reactor (CSTR). The reactivity ratios r,2 and rj, can be taken as 0.04 and 0.41, respectively. Construct a first-order Markov model using the dyad probabilities derived in Section 11.1. 

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