水溶液
纤维素
材料科学
化学工程
聚合物
水解
分子
纳米纤维素
高分子化学
有机化学
复合材料
化学
工程类
作者
Inseok Chae,Luis E. Paniagua-Guerra,Mica L. Pitcher,Roya Koshani,Mengxue Yuan,Yen‐Ting Lin,Jongcheol Lee,Steve Perini,Amir Sheikhi,Bladimir Ramos–Alvarado,Michael T. Lanagan,Seong H. Kim
出处
期刊:Cellulose
[Springer Nature]
日期:2023-07-15
卷期号:30 (13): 8051-8061
标识
DOI:10.1007/s10570-023-05361-y
摘要
Water molecules near cellulose nanocrystals (CNCs; produced via the sulfuric acid-catalyzed hydrolysis of wood pulp) are believed to relax slower than those in the bulk liquid, which may result in unique properties of CNC aqueous dispersions. This study analyzed the polarization behavior of water molecules in CNC aqueous dispersions and other reference samples using a dielectric relaxation spectroscopy (DRS) technique in the microwave frequency range (0.2–20 GHz). As the CNC concentration increases, two slow relaxation components become prominent. The comparison with DRS data of aqueous dispersions of nanoporous silica, polyvinyl alcohol (PVA), and hairy CNC (HCNC) with amorphous chains protruding from both ends suggested that these slow relaxation modes of water near CNC surfaces cannot be attributed to direct hydrogen bonding interactions with the hydroxyl (OH) groups exposed and immobilized at the solid surface. Instead, they are similar to the water molecules interacting with OH groups attached to flexible polymer chains. Molecular dynamics (MD) simulations of the polarization behavior of water near the (110) facet of cellulose Iβ crystals confirmed that the interactions of water molecules with the cellulose crystal surface do not cause slower relaxations in the frequency range studied via the DRS. These results indicated that the CNC surface cannot be depicted with the crystallographic facets of cellulose Iβ; instead, it resembles a polymer-brush surface on which the short glucan residues or fragments of the strong acid-catalyzed hydrolysis process are swollen and extended into the aqueous phase.
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