Separating Kinetics From Relaxation Dynamics in Reactive Soft Matter by Dielectric Spectroscopy

Broadband dielectric spectroscopy (BDS) is a widely used technique for the study of molecular and cooperative dynamics in soft matter due to its extremely wide time and frequency range and its widespread availability in materials science laboratories. A specific area for applications of BDS is systems that undergo time-dependent changes because of crystallization, other kinetic transitions, or chemical reactions, which alter thermophysical properties, such as relaxation times, the glass transition temperature, and the electrical conductivity at a timescale comparable to the measurement time. This article proposes three experimental approaches that allow to detect and to quantify effects of underlying kinetics on the dielectric spectra: 1) combining isothermal measurements with stepwise heating; 2) using a randomized frequency list to create artificial data “noise”; and 3) varying the effective heating rate up to 10 K/min to separate sample kinetics from relaxation dynamics. All three approaches are demonstrated and discussed on a Diels–Alder (DA) polymer network undergoing a reversible cure reaction.