The interest in cellulose nanocrystals (CNCs) have increased rapidly1 and it is foreseen that the application potential of CNCs can be significantly enhanced by surface modification.2 However, the functionalization of the CNCs by chemical methods is very challenging. Typically, unmodified CNCs are prepared by acid hydrolysis of cellulose fibers, followed by liquid exchange into organic solvents or freeze drying and re-dispersion, and subsequent post-functionalization. Herein, functional CNCs (F-CNCs) have been produced employing simultaneous acid hydrolysis and esterification, utilizing functional organic acids in the preparation step,3 thus omitting extra functionalization steps and tedious liquid exchange. In a facile manner, functionalities such as double and triple bonds, thiol groups and initiators for Atom Transfer Radical Polymerization (ATRP)4 has been incorporated simultaneously to the production of the CNCs, by the addition of 4-pentenoic acid, 2-propynoic acid, 3-mercaptopropionic acid and 2-bromopropionic acid, respectively. The F-CNCs were investigated by FTIR, XPS, elemental analysis, XRD and AFM. The thiol functionalized CNCs were reacted with Ellman´s reagent and the thiol content was estimated to be 766 μmol g-1. The alkyne functionalized CNCs were reacted with azide-functionalized disperse red 13 via azide-alkyne Huisgen cycloaddition5 and the content of triple bonds was estimated to be 335 μmol g-1. The ATRP-initiator functionalized CNCs were grafted with MMA by ATRP. We believe this study to be of outmost importance for the chemical modification of CNCs and hence for the production of functional CNCs. 1A. Dufresne, Nanocellulose:From Nature to High Performance Tailored Materials, Berlin,Walter de Gruyter, 2012 2Y. Habibi, Chem. Soc. Rev. 2014, 43(5), 1519-1542 3B. Braun and J. R. Dorgan, Biomacromolecules, 2009, 10(2), 334-341 4W. A. Braunecker, K. Matyjaszewski, Prog. Pol. Sci. 2007, 32, 93-146 5H. C. Kolb, M. G. Finn, K. Barry Sharpless, Angew. Chem. Int. Ed. 2001, 40, 2004-2021

Functional cellulose nanocrystals for ATRP and click chemistry-preparation and characterization

249th National Meeting (2015)

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