CNF R&D Center, Innovation Promotion Division, Oji Holdings Corporation, 1-10-6 Shinonome, Koto-ku, Tokyo 135-8558, Japan.
Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Biomacromolecules. 2021 Dec 13;22(12):5214-5222. doi: 10.1021/acs.biomac.1c01143. Epub 2021 Dec 2.
Phosphorylated cellulose nanofiber (CNF) is attracting attention as a newly emerged CNF with high functionality. However, many structural aspects of phosphorylated CNF remain unclear. In this study, we investigated the chemical structures and distribution of ionic functional groups on the phosphorylated CNF surfaces liquid-state nuclear magnetic resonance measurements of colloidal dispersion. In addition to the monophosphate group, polyphosphate groups and cross-linked phosphate groups were introduced in the phosphorylated CNFs. The proportion of polyphosphate groups increased as the phosphorylation time increased, reaching ∼30% of all phosphate groups. Only a small amount of cross-linked phosphate groups existed in the phosphorylated CNF after a prolonged reaction time. Furthermore, phosphorylation of cellulose using urea and phosphoric acid was found to be regioselective at the C2 and C6 positions. There existed no significant difference between the surface degrees of substitution at the C2 and C6 positions of the phosphorylated CNFs.
磷酸化纤维素纳米纤维（CNF）作为一种新兴的具有高功能的 CNF 引起了人们的关注。然而，磷酸化 CNF 的许多结构方面仍不清楚。在这项研究中，我们通过胶体分散的液相核磁共振测量研究了磷酸化 CNF 表面上离子官能团的化学结构和分布。除了单磷酸盐基团外，磷酸化 CNF 中还引入了多磷酸盐基团和交联磷酸盐基团。随着磷酸化时间的增加，多磷酸盐基团的比例增加，达到所有磷酸盐基团的约 30%。在延长的反应时间后，磷酸化 CNF 中仅存在少量交联的磷酸盐基团。此外，使用尿素和磷酸对纤维素进行磷酸化在 C2 和 C6 位置具有区域选择性。磷酸化 CNF 中 C2 和 C6 位置的表面取代度没有显著差异。
