title: Hydration control of the mechanical and dynamical properties of cellulose.
abstract: The mechanical and dynamical properties of cellulose, the most abundant biomolecule on earth, are essential for its function in plant cell walls and advanced biomaterials. Cellulose is almost always found in a hydrated state, and it is therefore important to understand how hydration influences its dynamics and mechanics. Here, the nanosecond-time scale dynamics of cellulose is characterized using dynamic neutron scattering experiments and molecular dynamics (MD) simulation. The experiments reveal that hydrated samples exhibit a higher average mean-square displacement above ∼240 K. The MD simulation reveals that the fluctuations of the surface hydroxymethyl atoms determine the experimental temperature and hydration dependence. The increase in the conformational disorder of the surface hydroxymethyl groups with temperature follows the cellulose persistence length, suggesting a coupling between structural and mechanical properties of the biopolymer. In the MD simulation, 20% hydrated cellulose is more rigid than the dry form, due to more closely packed cellulose chains and water molecules bridging cellulose monomers with hydrogen bonds. This finding may have implications for understanding the origin of strength and rigidity of secondary plant cell walls. The detailed characterization obtained here describes how hydration-dependent increased fluctuations and hydroxymethyl disorder at the cellulose surface lead to enhancement of the rigidity of this important biomolecule.
authors.affiliation: UT/ORNL Center for Molecular Biophysics, ‡Biology and Soft Matter Division, §Center for Structural Molecular Biology, and ○Chemical and Engineering Materials Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors.forename: Loukas
authors.initials: L
authors.lastname: Petridis
authors.forename: Hugh M
authors.initials: HM
authors.lastname: O'Neill
authors.forename: Mariah
authors.initials: M
authors.lastname: Johnsen
authors.forename: Bingxin
authors.initials: B
authors.lastname: Fan
authors.forename: Roland
authors.initials: R
authors.lastname: Schulz
authors.forename: Eugene
authors.initials: E
authors.lastname: Mamontov
authors.forename: Janna
authors.initials: J
authors.lastname: Maranas
authors.forename: Paul
authors.initials: P
authors.lastname: Langan
authors.forename: Jeremy C
authors.initials: JC
authors.lastname: Smith
mesh_terms: D002482:Cellulose / Q000737:chemistry*; D041822:Gluconacetobacter xylinus / Q000737:chemistry; D013314:Stress, Mechanical; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water; D002482:Cellulose