Different Conformations of Surface Cellulose Molecules in Native Cellulose Microfibrils Revealed by Layer-by-Layer Peeling

Abstract

Layer-by-layer peeling of surface molecules of native cellulose microfibrils was performed using a repeated sequential process of 2,2,6,6-tetramethylpiperidine-1-oxyl radical-mediated oxidation followed by hot alkali extraction. Both highly crystalline algal and tunicate celluloses and low-crystalline cotton and wood celluloses were investigated. Initially, the C6-hydroxy groups of the outermost surface molecules of each algal cellulose microfibril facing the exterior had the gauche-gauche (gg) conformation, whereas those facing the interior had the gauche-trans (gt) conformation. All the other C6-hydroxy groups of the cellulose molecules inside the microfibrils contributing to crystalline cellulose I had the trans-gauche (tg) conformation. After surface peeling, the originally second-layer molecules from the microfibril surface became the outermost surface molecules, and the original tg conformation changed to gg and gt conformations. The plant cellulose microfibrils likely had disordered structures for both the outermost surface and second-layer molecules, as demonstrated using the same layer-by-layer peeling technique.

Cross-polarization dynamics and conformational study of variously sized cellulose crystallites using solid-state 13C NMR

“…Indeed, the conformational heterogeneity is present in both the crystalline and noncrystalline regions. It has been reported that part of the molecules that exist close to the surface sit in a noncrystalline conformation even in the interior of the microfibril [23,24]. Our results also suggest this.…”

All-cellulose Materials Adhered with Cellulose Nanofibrils

“…The size then decreased with increasing concentration of zinc chloride, reaching 5.4 nm again in the Zn-3 sheet. The crystal size of 5.4 nm in the base sheet is reasonable given the pulp ratio of cotton and wood 24) . The reason that the crystal size increased in the Zn-1 sheet appears to be realignment of the cellulose microfibrils and/or cellulose chains during washing or drying.…”

Chemistry and Nanotechnology‐Oriented Strategies toward Nanocellulose for Human Water Treatment

“…[55,56] The biosynthesis conditions, such as the used raw materials (higher plants, green algae, some bacteria or animals), play vital role in the assembly of reactant agents, contributing to the generation of diverse products with different morphologies (Figure 5). [57][58][59] There are enhanced interactions between nanofibrillated celluloses and surrounding species, such as hydrophilic or hydrophobic molecules, organic or inorganic small molecules, nanoparticles, and even the biological materials, endowing the adsorbents with high environmental performance for disposal high amounts of contaminants.…”

“…[ 55,56 ] The biosynthesis conditions, such as the used raw materials (higher plants, green algae, some bacteria or animals), play vital role in the assembly of reactant agents, contributing to the generation of diverse products with different morphologies ( Figure ). [ 57–59 ]…”