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

Bis-ortho-diynylarene (BODA) monomers undergo radical mediated Bergman-type cycloaddition polymerization to yield polynaphthalene networks. This repor t describes the use of conventional and modulated temperature differential scanning calorimetry to compute the cure kinetic parameters of BODA monomer s with different spacer groups. Three different kinetic methods employed he re utilize non-isothermal dynamic thermal profiles to estimate activation e nergies (E-a = 28.7-33.5 kcal/mol [120-140 kJ/mol]) and the first order rat e constants (k similar to 10(-5) s(-1) at 210 degrees C) of polymerization. The results obtained from these methods show surprisingly good mutual agre ement and also reveal that varying the spacer group has marginal effect on the cure kinetics. It has also been shown that the reaction kinetic informa tion obtained from the dynamic methods must be corrected, when applied unde r isothermal conditions, to account for sample vitrification. The correctio n factor has been estimated using modulated temperature differential scanni ng calorimetry which is capable of monitoring the sample heat capacity in r eal time. (C) 2000 Elsevier Science Ltd. All rights reserved.