In situ observation of polyurea formation by rapid-scan time-resolved infrared spectroscopy

by fast time-resolved Fourier-transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy. This method enabled the analysis of the polyaddition reaction within 1 s and observation of intermolecular hydrogen bond formation. We observed the polyurea formation of different aliphatic and alicyclic monomers by recording the FTIR-ATR spectra every ∼0.07 s and analyzed the reaction kinetics. In the case of aliphatic monomers, strong hydrogen bonds were formed in the initial stage of polyurea formation, whereas in the case of alicyclic monomers, weak hydrogen bonds were initially formed, which strengthened as the reaction proceeded. These findings elucidate the role of monomer structure in the formation and hydrogen bonding state of polyurea and demonstrate the effectiveness of time-resolved FTIR-ATR spectroscopy as a technique for observing very fast reactions and intermolecular interactions.