Abstract
A new regioselective route is introduced for surface modification of biological colloids in the presence of water. Taking the case of cellulose nanofibers (CNFs), we demonstrate a site-specific (93% selective) reaction between the primary surface hydroxyl groups (C6-OH) of cellulose and acyl imidazoles. CNFs bearing C6-acetyl and C6-isobutyryl groups, with a degree of substitution of up to 1 mmol g−1are obtained upon surface esterification, affording CNFs of adjustable surface energy. The morphological and structural features of the nanofibers remain largely unaffected, but the regioselective surface reactions enable tailoring of their interfacial interactions, as demonstrated in oil/water Pickering emulsions. Our method precludes the need for drying or exchange with organic solvents for surface esterification, otherwise needed in the synthesis of esterified colloids and polysaccharides. Moreover, the method is well suited for application at high-solid content, opening the possibility for implementation in reactive extrusion and compounding. The proposed acylation is introduced as a sustainable approach that benefits from the presence of water and affords a high chemical substitution selectivity.
Original language | English |
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Pages (from-to) | 6966-6974 |
Number of pages | 9 |
Journal | Green Chemistry |
Volume | 23 |
Issue number | 18 |
DOIs | |
Publication status | Published - 21 Sept 2021 |
MoE publication type | A1 Journal article-refereed |
Funding
Prof. Watson Loh and the S?o Paulo Research Foundation (FAPESP; grant no. 2016/13926-7) are acknowledged for granting access to LUMiSizer, and Caroline Silva for experimental support. This research was funded in part by the Austrian Science Fund (FWF) (J4356), FAPESP (grant no. 2019/00370-9), the Academy of Finland (Project #311255, ?WTF-Click-Nano?) and the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement no. 788489).