On the polymorphic and morphological changes of cellulose nanocrystals (CNC-I) upon mercerization and conversion to CNC-II

Ersuo Jin, Jiaqi Guo, Fang Yang, Yangyang Zhu, Junlong Song*, Yongcan Jin, Orlando J. Rojas

*Corresponding author for this work

    Research output: Contribution to journalArticleScientificpeer-review

    91 Citations (Scopus)

    Abstract

    Polymorphic and morphological transformations of cellulosic materials are strongly associated to their properties and applications, especially in the case of emerging nanocelluloses. Related changes that take place upon treatment of cellulose nanocrystals (CNC) in alkaline conditions are studied here by XRD, TEM, AFM, and other techniques. The results indicate polymorphic transformation of CNC proceeds gradually in a certain range of alkali concentrations, i.e. from about 8% to 12.5% NaOH. In such transition alkali concentration, cellulose I and II allomorphs coexists. Such value and range of the transition concentration is strongly interdependent with the crystallite size of CNCs. In addition, it is distinctively lower than that for macroscopic fibers (12-15% NaOH). Transmission electron microscopy and particle sizing reveals that after mercerization CNCs tend to associate. Furthermore, TEMPO-oxidized mercerized CNC reveals the morphology of individual nanocrystal of the cellulose II type, which is composed of some interconnected granular structures. Overall, this work reveals how the polymorphism and morphology of individual CNC change in alkali conditions and sheds light onto the polymorphic transition from cellulose I to II.

    Original languageEnglish
    Pages (from-to)327-335
    Number of pages9
    JournalCarbohydrate Polymers
    Volume143
    DOIs
    Publication statusPublished - 5 Jun 2016
    MoE publication typeA1 Journal article-refereed

    Keywords

    • Cellulose I and II
    • Cellulose nanocrystals
    • CNC
    • Crystallinity
    • Crystallite size
    • Mercerization
    • Polymorphs

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