Journal
JOURNAL OF COLLOID AND INTERFACE SCIENCE
Volume 538, Issue -, Pages 51-61Publisher
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.jcis.2018.11.071
Keywords
Cellulose nanocrystals; PEO-based polymer grafting; Anionic surfactant; Temperature-induced phase transition
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Funding
- Brazilian agencies FAPESP [2016/25406-5]
- CNPq [159080/2013-4]
- CAPES [CAPES-PVE 71/2013]
- FAPESP [2014/24305-8]
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Hypothesis: Cellulose nanocrystals (CNCs) undergo precipitation in the presence of high concentrations of cationic surfactants in aqueous solutions. To avoid such behavior and/or to promote redispersion of CNC/surfactant mixtures, the CNC surface was grafted with poly di(ethylene oxide) methyl ether methacrylate, P(MEO(2)MA). Experiments: CNC-g-P(MEO(2)MA) was characterized using the following techniques C-13 solid-state nuclear magnetic resonance (C-13 SSNMR), Fourier-transform infrared spectroscopy - attenuated total reflection spectroscopy (FTIR-ATR) and thermal gravimetric analysis (TGA). Isothermal titration calorimetry (ITC), electrophoretic mobility, light scattering and high sensitivity differential scanning calorimetry (HSDSC) were used to study the interaction between CNC-g-P(MEO(2)MA) and ionic surfactants, dodecyltrimethylammonium bromide (C(12)TAB, cationic) and sodium dodecylsulfate (SDS, anionic) at temperatures below and above the LCST. Findings: CNC-g-P(MEO(2)MA) underwent phase separation above its lower critical solution temperature (LCST similar to 25 degrees C) and precipitated from solution as seen by HSDSC and transmittance experiments. When C(12)TAB was added to CNC-g-P(MEO(2)MA) it induced the precipitation that prevented the redispersion due to strong electrostatic interactions with the negative charges on the CNC surface. With increasing concentrations of SDS, the polymer phase transition temperature was increased, which can be used to redisperse the CNC complexes. By removing SDS from the mixture via dialysis, the CNC-g-P(MEO(2)MA) underwent subsequent phase transition. (C) 2018 Elsevier Inc. All rights reserved.
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