Effect of active‐group position in polymeric interactions

The effect of the position of a substituent along a polymer chain on the equilibrium constant in interpolymer interactions has been determined for equilibria involving the substituent. Polymers containing single dimethylamino groups have been equilibrated with coupling bidentate dinitro phenols, and the excluded‐volume effect determined. The magnitude of the hindrance to complex formation was found to be considerably greater for centrally substituted polymers than for end‐substituted polymers. However, for all polymers the measured effect is less than those expected from previous theoretical treatments of interpolymer reactions. Also, the size of the effect is less in the equilibria than found previously for interpolymer reactions. This suggests that the theoretical treatments that deal only with the effect of excluded volume on the transition complex may be oversimplifications.