Double stabilization mechanism of O/W Pickering emulsions using cationic nanofibrillated cellulose

Autor(es)

Silva, Caroline E. P. ^{[1, 2]} ; Tam, Kam C. ^[3] ; Bernardes, Juliana S. ^{[1, 4]} ; Loh, Watson ^[2]

Afiliação do(s) autor(es)

^[1] CNPEM, Brazilian Nanotechnol Natl Lab LNNano, BR-13083970 Campinas, SP - Brazil

^[2] Univ Estadual Campinas, UNICAMP, Inst Chem, CP 6154, BR-13083970 Campinas, SP - Brazil

^[3] Univ Waterloo, Dept Chem Engn, Waterloo, ON N2L 3G1 - Canada

^[4] Fed Univ ABC, Ctr Nat & Human Sci, BR-09210580 Santo Andre, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Journal of Colloid and Interface Science; v. 574, p. 207-216, AUG 15 2020.
• Citações Web of Science: 0

Resumo

Hypothesis: Hydrophobic oleic acid/water interfaces are negatively charged. Hence, the use of cationic nanocelluloses as stabilizers of Pickering emulsions could improve the colloidal stability due to the electrostatic complexation at the oil-water interface. Experiments: Two cationic nanofibrillated cellulose (cNFCs) with two degrees of substitution were prepared and used as stabilizers of Pickering emulsions. The adsorption of cNFCs at the oil: water interface was evaluated by interfacial tension, atomic force microscopy, and centrifugation measurements. LUMiSizer and optical microscopy techniques were used to analyze the colloidal stability and oil droplets morphology, respectively. Besides, the rheological behavior of the continuous aqueous phase was determined through flow and stress sweep curves. Finally, the dispersion of cNFCs in a diluted emulsion was visualized by cryogenic transmission electron microscopy (cryo-TEM). Findings: Cationic NFCs were more efficient in partitioning to the oil:water interface compared to their anionic analogous, oCNF. The electrostatic attraction between the positively charged trimethylammonium groups and the negatively charged deprotonated oleic acid reduced the interfacial tension and improved the colloidal stability of O/W Pickering emulsions. cNFCs dispersed in the aqueous phase were found to increase the viscosity, decelerating the oil drops coalescence. Therefore, the stabilization of cNFCs Pickering emulsions had a synergistic effect from the electrostatic complexation at the liquid-liquid interface and network formation in the aqueous phase, as visualized by cryo-TEM. (C) 2020 Elsevier Inc. All rights reserved. (AU)

• Processo FAPESP: 15/25406-5 - Organizando a matéria: colóides formados por associação de surfactantes, polímeros e nanopartículas
• Beneficiário: Watson Loh
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 17/50133-8 - Gel behavior of cellulose nanofiber smart materials
• Beneficiário: Juliana da Silva Bernardes
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 16/04514-7 - Estudo do uso de nanopartículas de celulose no controle reológico de fluidos complexos
• Beneficiário: Juliana da Silva Bernardes
• Modalidade de apoio: Auxílio à Pesquisa - Programa BIOEN - Regular