TOPOLOGICAL FEATURES IN CELLULOSE MICROFIBRILS STUDIED USING COARSE-GRAINED MOLECULAR DYNAMICS

Open Access
Author:
Ali, Fadil Abbas
Area of Honors:
Physics
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Vincent Henry Crespi, Thesis Supervisor
  • Richard Wallace Robinett, Honors Advisor
Keywords:
  • coarse-grained
  • cellulose
  • helicity
  • curvature
Abstract:
Cellulose is the most abundant organic polymer in the biosphere, yet its growth mechanism remains misunderstood. Compact and crystalline fibrils typically consist of anywhere in from eighteen to thirty individual glucan chains. After these strands have coalesced, interesting macroscopic features emerge, including twists and bends. This project seeks to determine how these features are related to the fibril’s overall stability, by implementing a coarse-grained model to see how their prevalence and behavior varies with fibril diameter. This model captures the anisotropic intermolecular interactions by modeling glucose rings as beads and glycosidic linkages as springs. These simulations revealed interesting qualitative information regarding a fibril’s stiffness, stimulating curiosity of how persistence length varies with fibril diameter. An interesting feature noticed from these simulations is that fibril bends may occur at regions where the helicity along the fibril changes abruptly; we are searching to characterize the correlations between these two phenomena. By understanding how these phenomena vary with fibril diameter, we can achieve a better understanding of how the preferred macroscopic structure is affects the cellulose fibrils’ stiffness, which gives insight on which structures yield greater stability.