Applications of characterization methods in polyurethane materials: analysis of microphase-separated structures

Polyurethanes (PUs) have been versatilely applied in various fields because of their preferable properties with both elasticity and hardness. Due to the thermodynamic incompatibility of hard segments and soft segments, the PUs generally have the microphase-separated structures, which could dramatically affect their chemical and mechanical properties. In this review, the characterization methods of microphase-separated structures in PU polymers, such as fourier transformed infrared spectroscopy (FTIR), atomic force microscopy (AFM), differential scanning calorimetry (DSC), and small-angle X-ray scattering (SAXS) are summarized and illustrated. The relationship between microphase-separated structures and PU properties is also discussed. This review will lay the theoretical foundation for the improvement on the application performance of PUs.