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.