The effect of surface modification on chemical and crystalline structure of the cellulose III nanocrystals.

Although the research on the cellulose allomorphs has been progressing for decades, many details especially in a nanoscale still require further exploration. In this article, the crystalline structure and morphology of cellulose III nanocrystals (CNC-III) are investigated after some typical modification routes. The results indicate that the crystalline structure of CNC-III is unsteady. After acetylation, hydrophobic cationization, polymer grafting and surface alkylation, CNC-III keep the original crystalline morphology but the crystallinity (62.8 %) decrease to 31.0 %, 42.5 %, 43.1 % and 43.8 %, respectively. However, after TEMPO-mediated oxidation and hydrophilic cationization, the crystalline structure of CNC-III transforms to the cellulose polymorph I and II, respectively. After modification, the dispersibility and thermal stability of CNC-III samples have been changed. Therefore, this systematic investigation is of great significance for understanding the effect of surface modification on the chemical and crystalline structure of CNC-III, which will provide a reference for future modifications and applications.