Intramolecular Reaction between Neighboring Functional Groups in Random Copolymers
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This Demonstration shows the effect of copolymer composition on the kinetics of an irreversible intramolecular reaction when only neighboring groups A and B take part in the reaction. The upper graph represents the evolution of the molar fraction of dyads in the copolymer as the reaction proceeds. The lower histogram for blocked groups B shows the distribution of the distances of blocked groups B to the nearest group A and vice versa for the blocked groups A to the nearest group B. The lower part of the window shows the average composition of the initial copolymer and the molar fraction of the blocked groups after the reaction is complete. The proportion of blocked groups is calculated using the monomer taken in deficiency.
Contributed by: A. A. Koledenkov (March 2019)
Open content licensed under CC BY-NC-SA
Select the "simple statistics" button to use the average composition of the copolymer to generate the starting copolymer. Select the button "considering copolymerization constants" to generate the starting copolymer based on the Mayo–Lewis equation with copolymerization constants and for monomers and , respectively.
If the initial monomer mixture contains mole fraction of monomer , the conditional probability that monomer follows monomer in the copolymer is
and that monomer follows monomer is
This Demonstration uses the reaction model for convenience, although in practice, cases of and are possible. The data for these cases is easily obtained from the reaction model , since for the second case, group is always located next to group , and group occupies two monomer units for the third case.
If group is blocked, the distance distribution to the nearest group is calculated, and vice versa. The distances are calculated after the reaction is complete. If the distance to the two reactive groups is the same, only one distance is taken into account, since only one reaction step is possible. The distribution of these distances is useful for reversible reactions and in the presence of rearrangements.