Amphiphilic Cellulose Nanocrystals for Enhanced Pickering Emulsion Stabilization

Abstract

Sulfated cellulose nanocrystals (CNC) with high surface charge density are inadequate for stabilizing oil− water emulsions, which limits their applications as interfacial stabilizers. We performed end-group modification by introducing hydrophobic chains (polystyrene) to CNC. Results showed that the modified CNC are more effective in emulsifying toluene and hexadecane than pristine CNC. Various parameters were investigated, such as concentration of particles, electrolytes, and polarity of solvents on the characteristics of the emulsions. This study provides strategies for the modification of cellulose nanocrystals to yield amphiphilic nanoparticles that enhance the stability of emulsions. Such systems, bearing biocompatible and environmentally friendly characteristics, are attractive for use in a wide range of industries spanning food, biomedicine, pharmaceuticals, cosmetics, and petrochemicals.

Interest of Pickering Emulsions for Sustainable Micro/Nanocellulose in Food and Cosmetic Applications

“…Generally, chemical modifications of cellulose have been made by grafting or adsorbing molecules on pristine cellulose surface, such as hydroxypropylmethyl groups [ 31 ], sodium carboxymethyl cellulose [ 32 ], dodecylamine [ 33 ], polystyrene [ 34 ], cinnamoyl chloride and butyryl chloride [ 35 ], phenyltrimethoxysilane [ 36 ] or octenyl succinic anhydride [ 30 , 37 ]. Others molecules have been grafted on cellulose to bring specific properties at PEs, as N -isopropylacrylamide, a thermo-responsive molecule [ 38 ], or poly[2-(dimethylamino)ethyl methacrylate], a pH-responsive molecule [ 39 ].…”

“…Nevertheless, some methods to modify cellulose may be harmful for health and/or environment. Tang et al [ 34 , 35 ] developed a strategy to produce amphiphilic nanocellulose (CNCs and CNFs) by grafting hydrophobic molecules via reductive amination. This modified nanocellulose was more effective than unmodified nanocellulose to stabilize PEs and would be biocompatible and environment friendly.…”

Chemische Modifizierung der reduzierenden Enden von Cellulosenanokristallen

“…Tang et al nutzten einen Grafting-to-Ansatz zur Synthese Te nsid-analoger,a mphiphiler CNC-g-Polystyrol-Nanopartikel füre ine verbesserte Stabilisierung von Wasser-in-Öl(w/ ç)-Emulsionen. [107] Ausgehend von Amino-terminiertem Polystyrol wurde die topochemische Modifizierung über eine reduktive Aminierung in DMF vorgenommen. Unklar ist hier allerdings,w ie die Mutarotation katalysiert wurde,w as eine mçgliche Adsorption von Polystyrol auf der CNC-Oberfläche anstelle der anvisierten, kovalenten REG-Modifizierung vermuten lässt.…”

“…[179] Verschiedene Celluloseproben -Baumwolle,Sulfitzellstoff und regenerierte Cellulosewurden bis zu ihrem "leveling-off degree of polymerization" ( Tr otz des geringen Vorkommens an REGs wurden Titrationsmethoden genutzt und geben Werte nahe den erwarteten fürC NCs.T ang et al quantifizierten beispielsweise REGs über zwei verschiedene chemische Methoden, gefolgt von einer potentiometrischen Titration. [107] Die erste Methode war die klassische "Hydroxylamin-Methode",b ei der die REG-Aldehyde mit Hydroxylaminhydrochlorid zum entsprechenden Oxim (Abbildung 14) und einem Mol HCl per REG umgesetzt werden. HCl wurde danach, unter Protokollierung der pH-Veränderungen, mit NaOH titriert, was einen REG-Wert von 24.…”

Alkali Hydrolysis of Sulfated Cellulose Nanocrystals: Optimization of Reaction Conditions and Tailored Surface Charge

“…Cellulose nanocrystals (CNCs) are a biorenewable resource that is environmentally friendly, and possess unique physical properties such as high crystallinity and aspect ratio, large surface area, and a propensity to self-assemble into chiral nematic phases [1,2,3]. Thus, they have garnered such uses as reinforcing agents and additives in nanocomposites, polymers, gels, and emulsions [4,5,6,7,8,9,10,11,12]. Recently, cotton gin motes were shown to be an additional effective biomass source material for the extraction of cellulose and the production of CNCs [13].…”