Study of denaturation and composition-dependent poly(ethylene oxide)–soy protein interactions: Structures and dielectric polarization

The significance of aggregated protein structures in tuning structures and dielectric polarization of poly(ethylene oxide) (PEO)/soy protein isolate (SPI) films was studied. The aggregated protein structures, subjected to denaturation processes, are expected to alter polymer–protein interactions, leading to diverse material structures, and properties. However, this is still insufficiently understood. In this study, SPI was modified via different denaturation processes including heat, sonication, and pH-control. According to structural analysis with scanning electron microscope, fluorescence imaging, X-ray diffraction, and Fourier transformed infrared spectroscopy, both denaturation conditions and SPI content affected PEO–SPI interactions, producing distinctive microstructures of PEO and SPI phases, which subsequently caused different dielectric properties in ferroelectric analysis. Particularly, sonication treated-SPI distinguished itself by generating a unique parabolic-like composition dependence of dielectric polarization, in contrast to other modified SPIs. Polymer/protein blends have shown great potential in biomedical and electronic applications, which will be further benefited by the findings in this study. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46561.