A THEORETICAL APPROACH TO THE THERMOCHEMISTRY OF RADICAL AND ANIONIC POLYMERIZATIONS OF VARIOUS UNSATURATED MONOMERS

In this work, we have calculated the thermodynamic parameters of the f irst steps of the free radical and anionic polymerizations of various unsaturated monomers, using ab initio methods of quantum chemistry. Th e enthalpies and entropies of polymerization were estimated assuming t hat they correspond to those of the model reaction A = B(p) + HABAH(p' ) --> HABABAH(p') where p and p' stand for the physical state of the c onsidered species. The enthalpies of polymerization were rationalized using the equation Delta H-p(0) = -Delta Sigma N(AB)E(AB) + SE(A = B) + SE(HABAH) - SE(HABABAH) where N-AB is the number of A-B bonds, E(AB) the corresponding bond energy, Delta Sigma N(AB)E(AB) the variation o f the sum of the bond energy terms, and SE(X) the thermodynamic stabil ization energy of compound X. The preferential mode of polymerization of each monomer was derived from the enthalpies of the initiation and initial propagation steps of the two types of polymerization. Thus, we were able to make some comments concerning the feasibility of the pol ymerization of the monomers under consideration.