Facile Preparation and Functionalization of Cellulose Microgels and their Properties and Application in Stabilizing O/W Emulsions

Abstract

The preparation and functionalization of cellulose microgels (CMGs) has been presented. Only a trace concentration of CMGs (< 0.2 wt.%) stabilized oil-in-water (O/W) emulsions and produced high internal phase emulsions (HIPE). The size and morphology of the CMGs were characterized with dynamic light scattering (DLS) and atomic force microscopy (AFM), and the structural properties were discussed. Based on the experimental results, the correlation between the amphiphilicity, and adsorption of the CMGs, and their capability to stabilize the emulsions, which are closely related to the cross-linking density of the CMGs, were elaborated. Having a porous percolating structure and being rich in free hydroxyl groups, the CMGs were functionalized by Fe3O4. The unique dispersibility of the Fe3O4-CMGs and their ability to stabilize the emulsions were investigated in detail. The results pave the way to a deeper understanding of Pickering emulsions stabilized by soft solvent-swollen materials and are expected to further expand the application of cellulose.

Pickering emulsions: Preparation processes, key parameters governing their properties and potential for pharmaceutical applications

“…For Pickering emulsion stabilization, nano-scale cellulose is used with various aspect ratios (from few nanometers to tens of nanometers in width and from tens of nanometers to few micrometers in length) ( Table 2). The nano-scale cellulose used can be cellulose nanocrystals (CNC) (also called cellulose microcrystals, nanoparticles whiskers, nanorods, rod-like or needle-like particles) [193,195,[198][199][200], microfibrillated cellulose (MFC) (also called cellulose nanofibers or nanofibrils) [196,197] or cellulose microgels [191]. In their review, Siro & Plackett [229] and Habibi et al [232] described the preparation methods of respectively MFC and CNC.…”

“…The source of the cellulose as well as the parameters under which the hydrolysis is performed drive the length and width of the CNC obtained. Cellulose microgels can be prepared by mechanical treatment of a cellulose hydrogel formed by the cross-linking of a cellulose suspension [191].…”

Spectroscopic and 1O2 Sensitization Characteristics of a Series of Isomeric Re(bpy)(CO)3Cl Complexes Bearing Pendant BODIPY Chromophores

“…11 Accordingly, numerous halogenated BODIPY derivatives featuring bromine or iodine substituents directly attached to, or in π-conjugation with the pyrrolic backbone have been synthesized and reported to efficiently access the triplet state. [16][17][18][19][20][21] Ligands bearing BODIPY moeitites have also been complexed with heavy transition metals such as Ru(II), [22][23][24] Pt(II), [25][26][27][28][29] Ir(III) [30][31][32] or Re(I) [33][34][35] to deliver systems that exhibit lower fluorescence quantum yields and, in some cases, detectable phosphorescence from the BODIPY triplet state following photoexcitation. Along these lines, we have reported a 2,2'bipyridine ligand functionalized with two BODIPY substituents at the 4-and 4'-positions (BB2), 36 and subsequently incorporated this ligand into a rhenium(I)tricarbonylchloride complex to form Re(BB2)(CO) 3 Cl (Scheme 1).…”

“…Additionally, Re(BB2)(CO) 3 Cl, Re(BB3)(CO) 3 Cl and Re(BB4)(CO) 3 Cl all show the ability to sensitize 1 O 2 , but Re(BB4)(CO) 3 Cl, which has the shortest average Re•••BODIPY separation, photosensitizes the formation of 1 O 2 with the highest quantum yield across the series. These constructs are notable as they form a structurally characterized set of isomeric homologues that add to the small number of BODIPY compounds tethered to a rhenium heavy atom to induce a triplet photochemistry, [33][34][35] and as new examples of rhenium(I) complexes capable of generating 1 O 2 upon irradiation with wavelengths of light longer than 500 nm. 11,33,40,41…”