KTH Royal Institute of Technology, School of Chemical Science and Engineering, Wallenberg Wood Science Center, Teknikringen 56, SE-100 44, Stockholm, Sweden.
KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Fibre and Polymer Technology, Teknikringen 56, SE-100 44, Stockholm, Sweden.
Carbohydr Polym. 2018 Feb 1;181:871-878. doi: 10.1016/j.carbpol.2017.11.065. Epub 2017 Dec 2.
EDC-mediated coupling has frequently been utilized to poly(ethylene glycol) functionalize (PEGylate) cellulose-based materials, but no work has previously been reported on the direct N-(3-dimethylaminopropyl)-N-ethylcarbodiimide (EDC)-mediated PEGylation of cellulose nanofibrils (CNF). Herein, we report the first study where CNF has been directly sterically stabilized with amine-terminated PEG employing N-hydroxysuccinimide (NHS)-assisted EDC-coupling. This work has shown that this coupling reaction is highly sensitive to the reaction conditions and purification procedures, and hence an optimized coupling protocol was developed in order to achieve a reaction yield. Elemental analysis of the nitrogen content also showed the successful PEGylation. It was also shown that a surprisingly low PEGylation (1%) is sufficient to significantly improve the colloidal stability of the PEGylated samples, which reached dispersion-arrested-state-transitions at higher concentrations than neat CNF. The colloidal stability was preserved with increasing ionic strength, when comparably long polymer chains were grafted, targeting only 1% PEGylation.
EDC 介导的偶联经常被用于聚乙二醇（PEG）功能化纤维素基材料，但之前没有关于直接使用 N-(3-二甲氨基丙基)-N-乙基碳二亚胺（EDC）对纤维素纳米纤维（CNF）进行 PEG 化的报道。在此，我们首次报道了使用 N-羟基琥珀酰亚胺（NHS）辅助 EDC 偶联，将胺封端的 PEG 直接对 CNF 进行空间稳定化的研究。这项工作表明，该偶联反应对反应条件和纯化程序非常敏感，因此开发了优化的偶联方案以实现反应收率。氮含量的元素分析也表明了 PEG 化的成功。此外，令人惊讶的是，低水平的 PEG 化（1%）就足以显著提高 PEG 化样品的胶体稳定性，PEG 化样品在更高浓度下达到分散相转变，而纯 CNF 则没有。当接枝了相对较长的聚合物链时，胶体稳定性随着离子强度的增加而保持，而 PEG 化的目标仅为 1%。
