Kinetics of nucleation-controlled polymerization of N,N′-bismaleimide-4,4′- diphenylmethane/barbituric acid

• Non-isothermal polymerization kinetics for BMI/BTA system studied.
• Kinetic parameters determined via model-fitting and model-free methods.
• Deconvolution successfully used to characterize complex polymerization process.
• Polymerization adequately described by nucleation Avrami-Erofeev models.
• Microgel particles of BMI/BTA formed during polymerization.

Non-isothermal polymerization kinetics of N,N′-bismaleimide-4,4′-diphenylmethane (BMI)/barbituric acid (BTA) was investigated by using DSC. Comparable extents of Michael addition reaction estimated independently by a molecular probe, hydroquinone (HQ), and the deconvolution technique using the Haarhoff-Van der Linde (HVL) function were achieved. Both the model-fitting and model-free methods were employed to determine the kinetic parameters for the polymerization of BMI/BTA. The kinetic parameters of the BMI/BTA system for the three distinct stages were determined by the model-free method with the aid of the deconvolution technique. The particle nucleation involved in the polymerization process was satisfactorily predicted by the nucleation Avrami-Erofeev models {f(α) = n(1 − α)[−ln(1 − α)](n − 1)/n} with n = 1.61 for Stage 1, n = 2.24 (Stage 2) and n = 2.77 (Stage 3). Microgel particles (MPs) of BMI/BTA were generated during polymerization. The particle size (d, z-average) of MPs was measured by dynamic light scattering (DLS). The least-squares best-fitted d versus t profile attained is d = 1 ×1 0−4t3 − 1.82 × 10−2t2 + 1.044t − 2.133 at 100 °C.