Iα to Iβ mechano-conversion and amorphization in native cellulose simulated by crystal bending

Pan Chen*, Yu Ogawa, Yoshiharu Nishiyama, Ahmed E. Ismail, Karim Mazeau

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)

Abstract

The bending of rod-like native cellulose crystals with degree of polymerization 40 and 160 using molecular dynamics simulations resulted in a deformation-induced local amorphization at the kinking point and allomorphic interconversion between cellulose Iα and Iβ in the unbent segments. The transformation mechanism involves a longitudinal chain slippage of the hydrogen-bonded sheets by the length of one anhydroglucose residue (~ 0.5 nm), which alters the chain stacking from the monotonic (Iα) form to the alternating Iβ one or vice versa. This mechanical deformation converts the Iα form progressively to the Iβ form, as has been experimentally observed for ultrasonication of microfibrils. Iβ is also able to partially convert to Iα-like organization but this conversion is only transitory. The qualitative agreement between the behavior of ultrasonicated microfibrils and in silico observed Iα → Iβ conversion suggests that shear deformation and chain slippage under bending deformation is a general process when cellulose fibrils experience lateral mechanical stress.

Original languageEnglish
Pages (from-to)4345-4355
Number of pages11
JournalCellulose
Volume25
Issue number8
DOIs
Publication statusPublished - 1 Aug 2018
Externally publishedYes

Keywords

  • Allomorphic conversion
  • Bending
  • Chain slippage
  • Kink
  • Molecular dynamics simulation

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