Ring Opening Polymerization of e-Caprolactone Initiated by Decamolybdate Anion: Determination of Kinetic and Thermodynamic Parameters by DSC and 1H-NMR

摘要

The aim of this work is the kinetic and thermodynamic study (by differential scanning calorimetry (DSC) and proton nuclear magnetic resonance (1H-NMR)) of the polymerization of e-caprolactone initiated by ammonium decamolybdate. By means of isothermal kinetics,enthalpies of reaction in the range 150–160C, as well asconstant rates of polymerization (using an nth-orderkinetics function model), were determined. From anArrhenius plot, activation energy (Ea 1/2 85.3 kJ/mol) andpreexponential factor (A 1/2 1.78108 min~1) wereestimated. Using dynamic methods, crystallization andmelting temperatures for the polymer obtained in situwere derived. Kinetic data for polymerization (obtained by1H-NMR) were fitted to 13 different model reactionfunctions. It was found that power law equations representbetter the conversion versus time plots for thissystem. On the basis of experimental facts, a coordinationinsertionmechanism involving molybdenum(V) species isproposed