Chirality and bound water in the hierarchical cellulose structure

Antti Paajanen, Sara Ceccherini, Thaddeus Maloney, Jukka A. Ketoja (Corresponding Author)

    Research output: Contribution to journalArticleScientificpeer-review

    16 Citations (Scopus)

    Abstract

    The origins of the unique properties of natural fibres have remained largely unresolved because of the complex interrelations between structural hierarchy, chirality and bound water. In this paper, analysis of the melting endotherms for bleached hardwood pulps indicates that the amount of non-freezing bound water (0.21 g/g) is roughly half of the amount of freezing bound water (0.42 g/g). We link this result to the two smallest constitutive units, microfibrils and their bundles, using molecular dynamics simulations at both hierarchical levels. The molecular water layers found in the simulations correspond quite accurately to the measured amount of non-freezing and freezing bound water. Disorder that results from the microfibril twist and amphiphilicity prevents co-crystallisation, leaving routes for water molecules to diffuse inside the microfibril bundle. Moreover, the simulations predict correctly the magnitude of the right-handed twist at different hierarchical levels. Significant changes in hydroxymethyl group conformations are seen during twisting that compare well with existing experimental data. Our findings go beyond earlier modelling studies in predicting the twist and structure of the microfibril bundle.
    Original languageEnglish
    Pages (from-to)5877-5892
    Number of pages16
    JournalCellulose
    Volume26
    Issue number10
    Early online date2019
    DOIs
    Publication statusPublished - 1 Jul 2019
    MoE publication typeA1 Journal article-refereed

    Keywords

    • Macrofibril
    • Twist
    • Cellulose
    • Microfibril
    • Molecular dynamics
    • Bound water

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