Interaction Effects between Cellulose and Water in Nanocrystalline and Amorphous Regions: A Novel Approach Using Molecular Modeling

Abstract

The hydrophilic/hydrophobic nature of cellulose is based on its structural anisotropy. Cellulose chains are arranged in a parallel manner and are organized in sheets stabilized by interchain OH–O hydrogen bonds, whereas the stacking of sheets is stabilized by both van der Waals (vdW) dispersion forces and weak CH–O hydrogen bonds. Cellulose has a strong affinity to itself and materials containing hydroxyls, especially water. Based on the preponderance of hydroxyl functional groups, cellulose polymer is very reactive with water. Water molecular smallness promotes the reaction with the cellulose chains and immediately formed hydrogen bonds. Besides that, vdW dispersion forces play an important role between these two reactive entities. They stabilize the cellulose structure according to the considerable cohesive energy in the cellulose network. Hydrogen bonding, electrostatic interactions, and vdW dispersion forces play an important role in determining the cellulose crystal structure during the cellulose-water interactions. As a result of these interactions, the volume of cellulose undergoes a meaningful change expressed not only by an exponential growth in amorphous regions, but also by an expansion in nanocrystalline regions. In addition, the volume change is associated with the swelling material expressed as a weight gain of the cellulose polymer. Molecular modeling using Accelrys Materials Studio allowed us to open a new horizon and is helpful for understanding cellulose-water interactions.

Hygroscopic, structural, and thermal properties of essential oil microparticles of sweet orange added with cellulose nanofibrils

“…This behavior is typical of wall materials which are very hygroscopic (Medeiros, Ayrosa, De Moraes Pitombo, & Da Silva Lannes, 2006), such as the carbohydrates used in this study. Cellulose has a large amount of hydroxyl functional groups in its structure, having a strong affinity for water (Chami Khazraji & Robert, 2013). Equilibrium moisture values in the range of 1.89%-22.23% were found for coffee oil microencapsulated with GA (Frascareli, Silva, Tonon, & Hubinger, 2012a).…”

Replication of annulus fibrosus through fabrication and characterization of polyurethane and cellulose nanocrystal composite scaffolds

“…This is to be expected as moisture increases, the hydrogen bonds between adjacent CNCs are broken, leading to a composite with individual CNCs acting as the filler instead of potential aggregates or networks of CNCs. 43 Therefore, water uptake increases load bearing within the matrix, leading to higher elongations and weaker moduli. Also, CNCs acting individually increases interfacial interactions between the CNCs and the PU 85A matrix, allowing the composite to act more similar to an isotropic material, which can be compared to the exceedingly large error bars for the dry composites, Figure 3.…”

Study of hydration properties of wheat bran as a function of particle size

“…Besides micropores, bran also contains nanopores which are found in the macromolecular matrix of bran cell walls (Chesson, Gardner, & Wood, 1997), and even within cell wall constituents such as cellulose. In cellulose, β (1→4) linked anhydro-D-glucose polymers are organized in cylindrically shaped microfibrils which in turn are organized in cylindrically shaped macrofibrils or cellulose fibers which contain nanopores as result of interfibrilar spaces (Khazraji & Robert, 2013;Topgaard & Söderman, 2001). Other fiber materials such as hemicellulose and lignin are also believed to consists of a porous matrix (Eastwood & Kay, 1979).…”

“…Cellulose, for instance, might not only contribute to water binding by means of its porous structure, it can also bind reasonable amounts of water through hydrogen bonding via its hydroxyl groups. Based on interaction models of cellulose and water for instance, it was predicted that amorphous regions of cellulose are able to bind 3.4 times their own weight in water (Khazraji & Robert, 2013). Considering that approximately 25% of bran consists of cellulose (Fraser & Holmes, 1959;Stone, 2006), a reasonable share of the strongly bound water might in fact be associated with cellulose.…”