Computer-aided molecular modeling of polymers. III. enthalpy of polymerization as a measure of stability

Abstract

Abstract A formalism of computational chemistry methods is presented to estimate the stability of vinyl polymers. This approach takes into account changes in electronic energy upon polymerization using quantum mechanical methods and contributions of the conformational energetics of the polymerized state using a molecular mechanics force field. A work term, ΔV, based upon the molecular volume difference between the monomer and the reactant, is shown to be negligible. For 10 structurally diverse vinyl polymers, the sum of the electronic and conformational energy differences between reactant and monomer states, AEp, has a high linear correlation with corresponding measured enthalpies of polymerization, ΔHp. The linear regression least square fit is ΔHp = 0.89 AEp-13.39. Errors due to possible contributions to AHp not included in the formalism reported here are probably small and/or relatively constant over the set of polymers studied. If this were not the case, a linear correlation between AHp and AEp, with ...