Hydrogen bonds and twist in cellulose microfibrils

• Published in: Carbohydrate polymers Vol. 175; pp. 433 - 439
• Main Authors: Kannam, Sridhar Kumar, Oehme, Daniel P., Doblin, Monika S., Gidley, Michael J., Bacic, Antony, Downton, Matthew T.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-11-2017
• Subjects: Cellulose; Hydrogen bonds; Microfibril; Twist; Twist; Hydrogen bonds; Cellulose; Microfibril
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2017.07.083

•The role of intra chain hydrogen bonds on the twist of cellulose was studied.•Multiple methods are used to explore the role of particular hydrogen bonds.•No in-chain hydrogen bond is found to play a definitive role in the twist.
There is increasing experimental and computational evidence that cellulose microfibrils can exist in a stable twisted form. In this study, atomistic molecular dynamics (MD) simulations are performed to investigate the importance of intrachain hydrogen bonds on the twist in cellulose microfibrils. We systematically enforce or block the formation of these intrachain hydrogen bonds by either constraining dihedral angles or manipulating charges. For the majority of simulations a consistent right handed twist is observed. The exceptions are two sets of simulations that block the O2–O6′ intrachain hydrogen bond, where no consistent twist is observed in multiple independent simulations suggesting that the O2–O6′ hydrogen bond can drive twist. However, in a further simulation where exocyclic group rotation is also blocked, right-handed twist still develops suggesting that intrachain hydrogen bonds are not necessary to drive twist in cellulose microfibrils.