A semiempirical quantum mechanical study of the cationic homopolymerization of expanding and potentially expanding monomer systems

The cationic homopolymerization reactions of expanding and potentially expa nding monomer systems were modeled and the energies of activation were calc ulated using the AM1 semiempirical quantum mechanical method. The results w ere used to determine the relative reactivity of study monomers with respec t to spiro-orthocarbonates (SOC) and epoxides. All expanding monomers studi ed were endothermic by 4-16 kcal/mol except the methylated bicyclic orthoes ters which had an enthalpy of reaction of essentially 0 kcal/mol. Three pot entially expanding monomers were exothermic by 3-18 kcal/mol. The energies of activation for all expanding monomers ranged from 28-37 kcal/mol. The en ergies of activation for SOCs and epoxides are approximately 32 and 0-3 kca l/mol, respectively [A.J. Holder, C.D. Harris, J.D. Eick, C.C. Chappelow, T HEOCHEM 507 (2000) 265-275, A.J. Holder, J.A. Morrill, D.A. White, J.D. Eic k, C.C. Chappelow, THEOCHEM 507 (2000) 63-73]. (C) 2001 Elsevier Science B. V. All rights reserved.