Kinetic Study of the Diels–Alder Reaction between Maleimide and Furan-Containing Polystyrene Using Infrared Spectroscopy

The Diels–Alder (D–A) reaction between furan and maleimide is a thermally reversible reaction that has become a vital chemical technique for designing polymer structures and functions. The kinetics of this reaction, particularly in polymer bulk states, have significant practical implications. In this study, we investigated the feasibility of utilizing infrared spectroscopy to measure the D–A reaction kinetics in bulk-state polymer. Specifically, we synthesized furan-functionalized polystyrene and added a maleimide small-molecule compound to form a D–A adduct. The intensity of the characteristic absorption peak of the D–A adduct was quantitatively measured by infrared spectroscopy, and the dependence of conversion of the D–A reaction on time was obtained at different temperatures. Subsequently, the D–A reaction apparent kinetic coefficient kapp and the Arrhenius activation energy Ea,D–A were calculated. These results were compared with those determined from 1H-NMR in the polymer solution states.