Ab initio study of structure and interconversion of native cellulose phases

Area of Science:

• Materials Science
• Computational Chemistry
• Solid-State Physics

Background:

• Cellulose I, the most abundant biopolymer, exists in multiple allomorphs (e.g., I(α) and I(β)).
• Understanding the structural differences and phase transitions between cellulose allomorphs is crucial for materials science and biotechnology.
• Previous experimental studies identified distinct hydrogen-bond patterns in cellulose I allomorphs.

Purpose of the Study:

• To investigate the structural properties of native cellulose I allomorphs using advanced computational methods.
• To examine the hydrogen-bond patterns within both cellulose I(α) and I(β) allomorphs.
• To elucidate the structural mechanism of the phase transition between cellulose I(α) and I(β).

Main Methods:

• Dispersion-interaction corrected Density-Functional Theory (DFT) simulations were employed.
• Constrained relaxation techniques were utilized to study the phase transition pathway.
• Theoretical structural data were compared with experimental findings for validation.

Main Results:

• Simulations accurately reproduced experimental data for cellulose I allomorph structures.
• Two distinct hydrogen-bond patterns were confirmed for both I(α) and I(β) allomorphs.
• A novel metastable intermediate phase was identified during the I(α) → I(β) phase transition, with its structural characteristics detailed.

Conclusions:

• The study validates the accuracy of dispersion-interaction corrected DFT for cellulose I structure prediction.
• The findings provide detailed structural insights into cellulose I allomorphs and their phase transformations.
• The discovery of a new intermediate phase offers a deeper understanding of cellulose I(α)-I(β) conversion mechanisms.