A generalization of the generalized Langevin equation (nonequilibrium dynamics) has recently been introduced in order to model chemical reactions which take place in environments with irreversible density and temperature changes (Hernandez, R., Somer, F. L. J. Phys. Chem. 1999, 103, 1064, 1070). The so-called irreversible generalized Langevin equation (iGLE) has been shown to be relevant to reaction polymerization when the irreversibility in the equilibrium solvent response is self-consistently coupled to the macroscopic average extent of polymerization, itself. In the present work, the iGLE is extended to allow the reacting polymers to be coupled to a finite number,w of neighboring polymers, thereby allowing for heterogeneity in the environment response.