A comparative guide to controlled hydrophobization of cellulose nanocrystals via surface esterification
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Surface esterification methods of cellulose nanocrystals (CNC) using acid anhydrides, acid chlorides, acid catalyzed carboxylic acids, and 1′1-carbonyldiimidazole (CDI) activated carboxylic acids were evaluated with acetyl-, hexanoyl-, dodecanoyl-, oleoyl-, and methacryloyl-functionalization. Their grafting efficiency was investigated using Fourier-transform infrared spectroscopy and 13C solid state NMR spectroscopy. Acid anhydride and CDI were found to be the most applicable reagents to graft short and long chain aliphatic carbons, respectively. The preservation of structural morphology and crystallinity of grafted CNCs were confirmed using transmission electron microscopy and X-ray diffraction. The hydrophobicity of grafted CNCs was evaluated by dispersing them in organic solvents with different Hansen’s solubility parameters. The dispersibility of grafted CNCs in organic solvents was improved by using never-dried CNCs as source materials and keep CNCs wet in their washing solvents after grafting, thus increasing the solvency range to disperse CNCs.
KeywordsCellulose nanocrystals Esterification Hydrophobicity Hansen’s solubility parameters Dispersibility
The authors would like to thank John Harwood from Purdue Interdepartmental NMR Facility for obtaining the 13C solid-state NMR spectra. The research was supported by the National Science Foundation IGERT sustainable electronic Grant #1144843-DGE and the Forest Products Laboratory under USDA Grant: 11-JV-11111129-118.
- Hartig SM (2013) Basic image analysis and manipulation in ImageJ. In: Taylor GP (ed) Current protocols in molecular biology. Wiley, Hoboken, pp 1–12Google Scholar
- Heinze T, Liebert T, Koschella A (2006) Esterification of polysaccharides. Springer-Verlag, Berlin. doi: 10.1007/3-540-32112-8
- Herrick FW, Casebier RL, Hamilton KJ, Sandberg KR (1983) Microfibrillated cellulose: morphology and accessibility. J Appl Polym Sci Appl Polym Symp 37:797–813Google Scholar
- Ibbett RN, Domvoglou D, Fasching M (2007) Characterisation of the supramolecular structure of chemically and physically modified regenerated cellulosic fibres by means of high-resolution Carbon-13 solid-state NMR. Polymer (Guildf) 48:1287–1296. doi: 10.1016/j.polymer.2006.12.034 CrossRefGoogle Scholar
- Reiner RS, Rudie AW (2013) Process scale-up of cellulose nanocrystal production to 25 kg per batch at the forest products laboratory. In: Postek MT, Moon RJ, Rudie AW, Bilodeau MA (eds) Production and applications of Cellulose nanomaterials. TAPPI Press, Peachtree Corners, pp 21–24Google Scholar
- Reising AB, Moon RJ, Youngblood JP (2012) Effect of particle alignment on mechanical properties of neat cellulose nanocrystal films. J Sci Technol For Prod Process 2:32–41Google Scholar