Interesting core–shell structure and “V-shape” shift: The property and formation mechanism of structural heterogeneity in cellulose hydrogel

Structural heterogeneity is a common phenomenon in cellulose hydrogel fabricated from ionic liquid. In this work, we characterized cellulose hydrogel wire by Fourier transform infrared spectroscopy (FTIR) image system and found its interesting core–shell structure. By pixel spectra analysis, we explored their distinctive hydrogen bond network in core and shell regions. To unveil the formation of heterogeneous core–shell structure, we tracked the cellulose regeneration procedure in situ by time-dependent attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. Inspired by an interesting red followed by blue band position shift, namely “V-shape” shift, we proposed a tri-step model of cellulose regeneration in favor of quantum calculation. The tri-step model can explain the formation of the heterogeneous core–shell structure.