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Atomistic molecular dynamics simulations on the interaction of TEMPO-oxidized cellulose nanofibrils in water

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Details

Original languageEnglish
Pages (from-to)3449–3462
Number of pages14
JournalCellulose
Volume23
Issue number6
DOIs
Publication statusPublished - 28 Sep 2016
Publication typeA1 Journal article-refereed

Abstract

Atomistic molecular dynamics simulations were carried out to obtain information on the rheological, aggregation and disintegration properties of carboxylated (TEMPO-oxidized) cellulose nanofibrils with different functionalization levels. The magnitude of the inter-fibril interaction was quantified for parallel nanofibrils using the umbrella sampling method. The obtained potential of mean force was found highly sensitive to the charge configuration for intermediate functionalization levels. This feature was further studied with an electrostatic model for similar charge configurations and system periodicity as in the case of the molecular dynamics simulations. The electrostatic contribution of the charged surfaces varied from repulsive to attractive depending on the distribution of the carboxylate groups and nearby counter-ions, as well as the distance between the fibrils. The simulated deviations from average behavior for single fibrils in both models suggest heterogeneity in their aggregation and disintegration behavior. This was seen in disintegration experiments, where the differences in disintegration energy and in the structural variation qualitatively agreed with the model predictions. As to aggregation behavior, the studied case with parallel fibrils reflects the upper boundary of the repulsive interaction.

ASJC Scopus subject areas

Keywords

  • Cellulose nanofibril, Electrostatic interaction, Functionalization, Molecular dynamics, TEMPO-oxidation

Publication forum classification

Field of science, Statistics Finland