A comparative molecular dynamics study of crystalline, paracrystalline and amorphous states of cellulose

Karol Kulasinski*, Sinan Keten, Sergey V. Churakov, Dominique Derome, Jan Carmeliet

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

77 Scopus citations

Abstract

The quintessential form of cellulose in wood consists of microfibrils that have high aspect ratio crystalline domains embedded within an amorphous cellulose domain. In this study, we apply united-atom molecular dynamics simulations to quantify changes in different morphologies of cellulose. We compare the structure of crystalline cellulose with paracrystalline and amorphous phases that are both obtained by high temperature equilibration followed by quenching at room temperature. Our study reveals that the paracrystalline phase may be an intermediate, kinetically arrested phase formed upon amorphisation of crystalline cellulose. The quenched structures yield isotropic amorphous polymer domains consistent with experimental results, thereby validating a new computational protocol for achieving amorphous cellulose structure. The non-crystalline cellulose compared to crystalline structure is characterized by a dramatic decrease in elastic modulus, thermal expansion coefficient, bond energies, and number of hydrogen bonds. Analysis of the lattice parameters shows that Iβ cellulose undergoes a phase transition into high-temperature phase in the range of 450-550 K. The mechanisms of the phase transition elucidated here present an atomistic view of the temperature dependent dynamic structure and mechanical properties of cellulose. The paracrystalline state of cellulose exhibits intermediate mechanical properties, between crystalline and amorphous phases, that can be assigned to the physical properties of the interphase regions between crystalline and amorphous cellulose in wood microfibrils. Our results suggest an atomistic structural view of amorphous cellulose which is consistent with experimental data available up to date and provide a basis for future multi-scale models for wood microfibrils and all-cellulose nanocomposites.

Original languageEnglish (US)
Pages (from-to)1103-1116
Number of pages14
JournalCellulose
Volume21
Issue number3
DOIs
StatePublished - Jun 2014

Keywords

  • Amorphous cellulose
  • Cellulose
  • Paracrystalline
  • Phase transition

ASJC Scopus subject areas

  • Polymers and Plastics

Fingerprint

Dive into the research topics of 'A comparative molecular dynamics study of crystalline, paracrystalline and amorphous states of cellulose'. Together they form a unique fingerprint.

Cite this