Aqueous Modification of Nano‐ and Microfibrillar Cellulose with a Click Synthon

• DOI: 10.1002/cssc.201501358
• Publication Date: 2015-11-27T10:47:06Z
• Authors: Hubert Hettegger; Marco Beaumont; Antje Potthast; Thomas Rosenau
• Keywords: Azides; Cycloaddition Reaction; Surface Properties; Nanofibers; Water; 02 engineering and technology; Silanes; Kinetics; Microscopy, Fluorescence; Click Chemistry; Cellulose; 0210 nano-technology

AbstractThe modification of cellulose as a renewable resource has received wide attention in research and industry. A major problem regarding chemical modification, including heating and drying, is related to hornification that causes pore‐system collapse and results in decreased reactivity and changes in the 3D structure of the material. A mild and green approach for the modification of different never‐dried and thus wet cellulose substrates (pulp, nanostructured celluloses, and viscose fibers) by an alkoxysilane‐azide in water is presented. A kinetic study of the silanization reaction demonstrates that alkoxy‐trans‐silanization of the cellulose surface is accomplished in water as a suspension medium within a few hours at room temperature. The resulting, azido‐equipped celluloses are widely applicable precursor materials for subsequent functionalization by so‐called click chemistry, for example, with a fluorescent Rhodamine derivative as a representative reagent. Successful covalent bonding was shown by GPC and a model reaction. The 3D structure of the materials remained intact, as was inter alia visualized by optical and fluorescence microscopy.