Intrinsic symmetry of the A_AB_b‐type distribution

By taking an A_aB_b‐type polymerisation as an example , an intrinsic symmetry of the equilibrium number fraction distribution of species is revealed. The symmetry shows that the distribution is invariant under transformation between the variables which describe the total system and the variables which describe the sol. It results that, when the polymer quantities for the pre‐gel regime are given, the corresponding quantities for the post‐gel regime can easily be obtained. As an illustration, the k th radius of an A_aB_b‐type polymerisation is discussed.