Faculty and Student Publications
Document Type
Article
Publication Date
1-1-2021
Abstract
Surface modification of cellulose nanocrystals (CNCs) was conducted by an oxa-Michael addition of primary hydroxyl groups on the CNC surface with N-Benzylmaleimide (BnM). Six principles of green chemistry were used to obtain the hydrophobized CNC. Two catalytic approaches were used, a self-catalyzed reaction where alkyl sulfuric acid on the surface of the CNC was the catalyst, and a base-catalyzed approach using triethylamine (TEA). DMSO was chosen as reaction solvent due to its low cost, low toxicity and ability to disperse native CNC compared to other polar diprotic solvents. NMR and FTIR studies confirmed the successful modification of CNCs in both reaction routes. The TEA-catalyzed reaction showed a higher BnM conversion at 70 °C after 72 h (46 ± 2%) compared to the self-catalyzed reaction at 100 °C (24 ± 2%). Since BnM was added at a two-fold excess compared to superficial primary –OH groups, these had estimated conversions of 92% and 48%, for the base catalyzed and acid catalyzed routes, respectively. Zeta potential measurements suggest, the sulfate groups were retained after the modification reaction. AFM demonstrated no change in particle morphology after modification. Modified CNCs degraded at a higher temperature (390 ± 8 °C) when the reaction was catalyzed by TEA compared to native CNCs and the self-catalyzed product (220 ± 10 °C). Contact angle measurements demonstrated the increased hydrophobicity of the modified nanoparticles. Visual inspection and UV–vis spectroscopy demonstrated the modified CNCs had an increased affinity towards organic solvents like acetone, acetonitrile and toluene.
Relational Format
journal article
Recommended Citation
Hasan, M. J., Johnson, A. E., & Ureña-Benavides, E. E. (2021). “Greener” chemical modification of cellulose nanocrystals via oxa-Michael addition with N-Benzylmaleimide. Current Research in Green and Sustainable Chemistry, 4, 100081. https://doi.org/10.1016/j.crgsc.2021.100081
DOI
10.1016/j.crgsc.2021.100081
Accessibility Status
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