Bergman cyclopolymerization kinetics of bis-ortho-diynylarenes to polynaphthalene networks. A comparison of calorimetric methods

Abstract

Bis-ortho-diynylarene (BODA) monomers undergo radical mediated Bergman-type cycloaddition polymerization to yield polynaphthalene networks. This report describes the use of conventional and modulated temperature differential scanning calorimetry to compute the cure kinetic parameters of BODA monomers with different spacer groups. Three different kinetic methods employed here utilize non-isothermal dynamic thermal profiles to estimate activation energies (Ea=28.7–33.5kcal/mol [120–140kJ/mol]) and the first order rate constants (k∼10−5s−1 at 210°C) of polymerization. The results obtained from these methods show surprisingly good mutual agreement and also reveal that varying the spacer group has marginal effect on the cure kinetics. It has also been shown that the reaction kinetic information obtained from the dynamic methods must be corrected, when applied under isothermal conditions, to account for sample vitrification. The correction factor has been estimated using modulated temperature differential scanning calorimetry which is capable of monitoring the sample heat capacity in real time.