Pickering emulsion stabilized with fibrous nanocelluloses: Insight into fiber flexibility-emulsifying capacity relations

The properties of Pickering emulsions stabilized by bacterial cellulose nanofibrils and its retarding effect on lipid digestion

The rate of lipid digestion can be delayed by the interface modulation of O/W Pickering emulsions. In this study, bacterial cellulose nanofibrils prepared by ball milling synergized with electron beam irradiation (B-IB50) were used as stabilizers to prepare Pickering emulsions. Results showed that B-IB50 formed emulsion systems with good stability. Especially when the content of B-IB50 was >0.6 wt%, emulsions showed excellent storage and environmental stability. Notably, at pH 2.0, the electrostatic repulsion between fibrils was weakened leading to closer cross-linking and giving better protection to the oil droplets. When the content of B-IB50 in emulsions increased from 0.2 wt% to 1.0 wt%, the release of FFA decreased from 66.7 % to 37.8 % during digestion, which indicated that the presence of more B-IB50 inhibited the digestion of lipids. Main mechanisms were proposed for the results: (1) B-IB50 formed a dense interface layer that reduced the binding area of bile salts and lipases; (2) B-IB50 formed the three-dimensional network structure limiting the displacement of bile salts and lipases, thereby reducing the binding to lipids. This study provided theoretical ideas for developing emulsion-based functional foods with lipid-reducing effects.

Subcritical water extraction improves the ability of Auricularia cornea var. Li. Polysaccharides to stabilize hydrogels and emulsion gels

In this work, polysaccharides from Auricularia cornea var. Li. (ACP) were extracted by a novel subcritical water extraction (SWE) method. Their structural properties and ability to stabilize hydrogels and emulsion gels were investigated and compared with those obtained by the conventional hot water extraction (HWE) method. The results showed that the polysaccharide yield of SWE (45.11 ± 0.23 %) was higher than that of HWE (17.85 ± 0.51 %). The two polysaccharides had the same type of monosaccharides but different compositions, and the molecular weight of ACP-SWE was slightly lower. The molecular conformation of ACP-HWE exhibited a long-chain structure, whereas ACP-SWE was multi-branched with obvious entanglements between the molecular chains. Both polysaccharides were able to form gels at concentrations above 1.0 %, with the ACP-SWE hydrogel having a denser network structure with better rheological and textural properties. ACP-SWE also had a greater ability to stabilize emulsion gels. By adjusting the polysaccharide concentration (c, 0.2 %-1.0 %) and the oil phase volume fraction (φ, 0.4-0.8), ACP-SWE emulsion gels could be prepared in a single step of shear homogenization. This work revealed that the adsorption of ACP-SWE at the oil-water interface and cross-linking in the bulk phase, together with the filling effect of oil droplets, contributed to the stabilization of ACP-SWE emulsion gels.

Pore formation mechanism and size regulation study of atmospheric dried cellulose nanofiber aerogel templated by emulsions

Atmospheric pressure drying (APD) method holds great promise in the large-scale production of aerogels without specialized equipment and critical conditions. However, atmospheric-dried cellulose- based aerogels are challenged by the collapse of the pore walls induced by the capillary force that arises during solvent evaporation. This study prepared an atmospheric dried cellulose nanofiber (CNF) aerogel with a low shrinkage rate (17.31 %), low density (26.5 mg/cm3), high porosity (97.53 %), excellent mechanical compressive strength (9197 Pa at 50 % strain), and adjustable pore size by embedding oil-in-water (O/W) emulsion templates in an ionically crosslinked CNF network. The effect of the emulsion template, network crosslinking density, and the solvent displacement process on the aerogel formability was studied to elucidate the pore formation mechanism. Additionally, the effect of emulsion droplet size on the aerogel pore size was studied. This work is of great significance in understanding the construction mechanism of atmospheric dried aerogels.

Cinnamon essential oil -loaded bagasse cellulose/hydroxypropyl-β-cyclodextrin microparticles with sustained-release property and its application in grapes preservation

This study investigate the feasibility of cinnamon essential oil-loaded bagasse cellulose/hydroxypropyl-β-cyclodextrin (CEO/BC/HP-β-CD) microparticles with sustained-release, using BC and HP-β-CD as co-encapsulation agents. CEO/BC/HP-β-CD was prepared by simple and easy-to-operate methods. The SEM confirms that it has a dense flocculent structure, and CEO is fixed to form a three-dimensional (3-D) network and stably arranged. The FTIR and XRD show that the co-cross-links among CEO, BC and HP-β-CD form inclusion complexes. 18 days (25 °C), different humidity and different light intensities of stability experiments show that the co-encapsulation of HP-β-CD and BC can significantly improve the low stability and control the release of CEO. On the antibacterial test, the diameter of inhibition zone of CEO/BC/HP-β-CD is significantly larger than that of CEO (180 mm, and 112 mm). To evaluate the preservation effect, grapes were treated with blank, 0.1 ml /kg CEO, 1.85 g/kg CEO/ HP-β-CD and 2.5 g/kg CEO/ HP-β-CD. Compared with blank, CEO/BC/ HP-β-CD significantly reduce the shedding rate (reductions of 33.97 %), delay the decrease of TSS, DPPH and VC content (delay of 42.95 %, 22.73 % and 44.51 %). Compare with CEO, CEO/BC/ HP-β-CD has a long-term preservation effect and mask strong small. This study improves the utilization value of BC, provides a new method for grape preservation.

Sunflower stem pith cellulose with different allomorphic nanocrystals for oil-in-water emulsions

Pickering emulsions utilize colloidal particles as stabilizers instead of traditional surfactants, offering the advantages of low dosage and high stability, and cellulose nanofibers (CNF) as a stabilizer for Pickering emulsions has been widely attracted by food, cosmetics and pharmaceuticals. However, the emulsification properties of CNF are affected by the crystalline form and length-diameter ratio of CNF. In this work, we investigate the stabilizer effect of different cellulose crystal types (CNF I, CNF II and CNF III) on Pickering emulsions. CNF I was a fibrous structure (Length/Diameter = 95.3), while CNF II and CNF III appeared as ellipsoidal nanoparticles with a "Needle-like" structure, and the aspect ratios of CNF II and CNF III averaged were 11.3 and 44.1. CNF I with high length-diameter ratio exhibited better emulsification properties. Meanwhile, Pickering emulsions stabilized by CNF II exhibited significantly smaller droplet sizes (D3, 2), approximately one time smaller than those stabilized by CNF I and CNF III. However, when the emulsions were left to stand for 14 days, the cellulose-stabilized emulsions were significantly not as good as the emulsions stabilized by CNF I and CNF III, probably due to the lower absolute value of zeta potential of CNF II. Overall, the Pickering emulsions prepared with CNF II were less favorable when compared to those stabilized by CNF I and CNF III. This comparative investigation advances fundamental understanding of cellulose-mediated Pickering stabilization mechanisms and facilitates targeted applications in emulsion-based formulations across multiple industrial sectors.

Preparation and properties of hydrogels with different forms of nanocellulose and low methoxyl pectin

Different proportions of cellulose nanofibers (CNFs)/cellulose nanocrystals (CNCs) and low methoxyl (LM) pectin were used to prepare hydrogels. By analyzing the apparent morphology, gel strength, rheological characteristics, microstructure, and interaction between cellulose and LM pectin, the characteristics of hydrogels created by the combination of different forms of nanocellulose and LM pectin were compared. At the same concentration, the strength of hydrogel formed by the combination of CNCs and LM pectin was higher than hydrogel formed by the combination of CNFs and LM pectin, which was consistent with the gel structure. The gel formed by the combination of LM pectin and CNFs had stronger viscoelasticity than the gel formed by the combination of LM pectin and CNCs. When the ratio of LM pectin to CNFs/CNCs is 0.5/0.5, a better gel network structure is formed, and the viscoelastic properties of the gel formed at this concentration under shock conditions are better protected.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-024-01684-z.

Highly Persistent and Robust Emulsion Stabilized by Hierarchical Cellulose Microgel through Stereo-hindrance under Extreme Conditions

Emulsion stabilization oil-in-water under harsh conditions (e.g., hypersaline, acid and alkali, and high temperature) is a great challenge for conventional emulsion stabilizers, including surfactants or particles. Herein, a persistent and robust emulsion under harsh conditions is achieved via a sustainable solution based on a hierarchical cellulose microgel (h-CMG). h-CMG in aqueous suspension establishes stable 3D networks by its nanotentacles and microbody, which can spatially hinder the approach and coalescence of droplets to each other and stabilize the emulsion. Unlike the emulsion stabilized by minimizing the interfacial energy and protecting the water/oil interface, the emulsion spatially stabilized by h-CMG exhibits extensive tolerance to extreme conditions and the feature of stable high internal phase emulsion (80%, v/v). The related droplet size and emulsion volume are almost unchanged in the pH range of 1 to 14, in NaCl aqueous solution of 2 mol/L, or even at 80 °C for 12 h. This genuine biobased emulsifier is highly favorable to the food, cosmetics, and pharmaceutical industries without the risk of nanotoxicity, and it also can provide a reliable emulsifier for the chemical and drilling industries involving harsh operation circumstances.

Pérez S, Velásquez. Cock JA, Vélez-Acosta L, Gañán-Rojo P, Zuluaga-Gallego R. A Novel French-Style Salad Dressing Based on Pickering Emulsion of Oil-Water Lycopene from Guava and Cellulose Nanofibers

The objective of this research was to assess the potential of a Pickering emulsion based on lycopene extracted from guava by sunflower oil-water and cellulose nanofibers (CNFs) isolated from banana residues as a novel ingredient for a French-style salad dressing. The aim was to determine the impact of this emulsion on the stability and rheological properties of the dressing as well as ascertain the presence of lycopene in the final product. The particle size distribution, rheological properties, and emulsion stability of the Pickering emulsion and salad dressing were evaluated. The sample exhibiting the optimal stability condition contained 0.5 wt.% of CNFs (EPI0.5). In order to prepare the French salad dressing based on this Pickering emulsion, three concentrations of vinegar were analyzed. All samples contained white salt and sugar. The findings suggest that alterations in emulsion stability may be influenced by the vinegar content and the presence of salt, particularly during the storage period, which also affects the concentration of lycopene. Notwithstanding these findings, the untrained panelists expressed a favorable opinion and acceptance of the dressings, indicating that the product could serve as an alternative means of enriching food through the incorporation of beneficial substances such as lycopene.

Effect of salt ions (Na+, Ca2+ and Mg2+) and EOR anionic and nonionic surfactants on the dispersion stability of cellulose nanocrystals

The application of cellulose nanocrystals (CNCs) in enhanced oil recovery (EOR) is a developing hotspot. To improve the stability of CNCs in salt environments, the effects of sodium dodecylbenzene sulfonate (SDBS) and polyoxyethylene sorbitan monooleate (Tween 80) on the stability of CNCs in the presence of sodium (Na+), calcium (Ca2+) and magnesium (Mg2+) were investigated. The range of salt ions and the stability mechanism for improving the CNCs stability in the presence of SDBS and Tween 80 were pointed out. SDBS improved the stability of CNCs in the presence of 30-100 mM Na+, 1-2 mM Ca2+ and 2 mM Mg2+, respectively. Tween 80 improved the stability of CNCs in the presence of Na+ ≤ 300 mM, Ca2+ ≤ 10 mM and Mg2+ ≤ 10 mM, respectively. The mechanism was explained by the bridging effect of salt ions, electrostatic effect and spatial stability effect. The combined systems of surfactants (SDBS and Tween 80) with CNCs exhibited strong emulsifying properties, low interfacial tension (0.023 mN/m and 1.85 mN/m), and the ability to alter the wettability of oil wet rocks. This made the combined systems have better oil displacement performance.

Stabilization of Oil-in-Water Pickering Emulsions by Surface-Functionalized Cellulose Hydrogel

An amphiphilic cellulose (CLH) hydrogel was synthesized via grafting of quaternary ammonium groups onto cellulose. The structural properties of CLH were characterized via Fourier transform infrared (FTIR)/13C solid-state NMR spectroscopy, elemental (CHN) analysis, particle size distribution (PSD), thermogravimetric analysis (TGA), and wettability was assessed through contact angle measurements. Pickering emulsions of apolar oils in water were prepared using variable weights of the CLH hydrogel as the stabilizing agent, along with different methods of agitation (mechanical shaking and sonication). The characterization results for CLH provide support for the successful grafting of quaternary ammonium groups onto cellulose to produce hydrogels. Different methods of agitation of an oil/water mixture revealed the formation of an oil-in-water (O/W) Pickering emulsion that was stable to coalescence for over 14 days. The resulting emulsions showed variable droplet sizes and stability according to the dosage of CLH in the emulsion and the agitation method, where the emulsion droplet size is related to the particle size of CLH. The addition of methyl orange (MO), a probe to evaluate the phase partitioning of the dye, had minor effects on the emulsion droplet size, and the emulsion prepared with 0.8 wt.% of CLH and agitated via sonication exhibited the smallest droplet size and greatest stability. This study is anticipated to catalyze further research and the development of low-cost and sustainable biopolymer hydrogels as stabilizers for tunable Pickering emulsion. Grafted cellulose materials of this type represent versatile stabilizing agents for foods, agrochemicals, and pharmaceutical products and technologies.

Structure, rheology and stability of walnut oleogels with different carboxylation degree of cellulose nanofiber

The effects of carboxylation degree (0.3-2.4 mmol/g) of cellulose nanofiber (CNF) on the microstructure and mechanical properties of edible walnut oleogels were comprehensively examined. The oleogels were well prepared by emulsion-templated approach for potential substitute of conventional saturated or trans-fats in food products. The results demonstrated that the oil-binding capacity (OBC) and textural strength of oleogels enhanced with the increase of CNF carboxyl content, while the structural strength (G' in rheological measurement) and the resistance to shear thinning was first decreased and then increased. It possibly reflected the competition on the dominant structuring mechanism by hydrogen bonding from cellulose hydroxyl groups and electrostatic interactions from -COONa function. With the combined mechanism, oleogel with low structural strength and relatively high OBC (CNF carboxyl content of 1.2 mmol/g, OBC >83 %, G' ≈ 7 × 104 Pa and firmness of 0.30 N) and oleogel with enough structural rigidity and high OBC (CNF carboxyl content of 1.8 mmol/g, OBC >89 %, G' of up to 1.7 × 105 Pa, and firmness of up to 0.66 N) were both fabricated. This reveals the feasibility of regulating oleogel structure and textual properties by using CNF as the unique oleogelator and simply changing its surface carboxyl function.

Palm-based nanofibrillated cellulose (NFC) in carotenoid encapsulation and its incorporation into margarine-like reduced fat spread as fat replacer

Nanofibrillated cellulose (NFC) from plant biomass is becoming popular, attributed to the protective encapsulation of bioactive compounds in Pickering emulsion, preventing degradation and stabilizing the emulsion. NFC, as a natural dietary fiber, is a prominent fat replacer, providing a quality enhancement to reduced-fat products. In this study, NFC Pickering emulsions were prepared at NFC concentrations of 0.2%, 0.4%, 0.6%, 0.8%, and 1% to encapsulate carotenoids. The NFC Pickering emulsions at NFC concentrations of 0.4%, 0.6%, 0.8%, and 1% were incorporated into margarine-like reduced fat (3%) spreads as the aqueous phase. Characterization of both NFC Pickering emulsion and the incorporated NFC Pickering emulsion, margarine-like reduced fat spreads, was conducted with mastersizer, rheometer, spectrophotometer, and texture analyzer. The particle size (73.67 ± 0.35 to 94.73 ± 2.21 nm), viscosity (138.36 ± 3.35 to 10545.00 ± 567.10 mPa s), and creaming stability (25% to 100% stable) of the NFC Pickering emulsions were increased significantly when increasing the NFC concentration, whereas the encapsulation efficiency was highest at NFC 0.4% and 0.6%. Although imitating the viscoelastic solid-like behavior of margarine was difficult, the NFC Pickering emulsion properties were still able to enhance hardness, slip melting point, and color of the reduced fat spreads compared to the full-fat margarine, especially at 0.6% of NFC. Overall, extensive performances of NFC can be seen in encapsulating carotenoids, especially at NFC concentrations of 0.4% and 0.6%, with the enhancement of Pickering emulsion stability while portraying futuristic possibilities as a fat replacer in margarine optimally at 0.6% of NFC concentration. PRACTICAL APPLICATION: Nanocellulose extracted from palm dried long fiber was utilized to encapsulate carotenoids and replace fats in margarine-like reduced fat (3%) spreads. Our study portrayed high encapsulation efficiency and successful fat replacement with promising stability performances. Hence, nanocellulose displayed extensive potential as encapsulating agents and fat replacers while providing quality and sustainability enhancements in reduced-fat food.

Chitin nanocrystals-stabilized emulsion as template for fabricating injectable suspension containing polylactide hollow microspheres

One of the promising applications of rod-like chitin nanocrystals (ChNCs) is the use as particle emulsifier to develop Pickering emulsions. We reported a ChNC-stabilized oil-in-water emulsion system, and developed a Pickering emulsion-templated method to prepare polylactide (PLA) hollow microspheres here. The results showed that both non-modified ChNCs and acetylated ChNCs could well emulsify the dichloromethane (DCM) solution of PLA-in-aqueous mannitol solution systems, forming very stable emulsions. At the same oil-to-water ratios and ChNC loadings, the emulsion stability was improved with increasing acetylation levels of ChNCs, accompanied by reduced size of droplets. Through the solvent evaporation, the PLA hollow microspheres were templated successfully, and the surface structure was also strongly dependent on the acetylation level of ChNCs. At a low level of acetylation, the single-hole or multi-hole surface structure formed, which was attributed to the out-diffusion of DCM caused by the solvent extraction and evaporation. These surface defects decreased with increased acetylation levels of ChNCs. Moreover, the aqueous suspension with as-obtained PLA microspheres revealed shear-thinning property and good biocompatibility, thereby had promising application as injectable fillers. This work can provide useful information around tuning surface structures of the Pickering emulsion-templated polymer hollow microspheres by regulating acetylation level of ChNCs.

Investigating the Emulsifying Mechanism of Stereoisomeric Sugar Fatty Acyl Molecular Gelators

The emulsifying mechanism of supramolecular stereoisomeric sugar fatty acyl molecular gelators was evaluated. In-house-synthesized mannitol dioctanoate (M8) and sorbitol dioctanoate (S8) were tested. The stereoisomeric difference between the sugar groups significantly affected the gelation and emulsifying properties of the gelators. M8 and S8 formed oleogels at 2 and 3.5% (w/v) and emulsified water up to 30 and 60% (v/v), respectively. Microscopy showed that the gelator fibers are at the W/O interfaces, demonstrating a solid particle or network mode of stabilization. The long fibers of M8 were unable to completely encompass the water droplets, resulting in poor emulsification. Small, hair-like fibers of S8 showed better emulsification. When sunflower wax (SFW, 1% w/v) was added as a coemulsifier, synergetic action between the wax and S8 improved the stability of emulsions. Such synergy was not seen between SFW and M8, henceforth emulsion stability was not improved. This study proved that a subtle stereoisomeric difference at the molecular level can greatly alter the supramolecular and emulsifying properties of sugar-fatty acyl compounds.

Effects of bacterial cellulose/thyme essential oil emulsion coating on the shelf life of chilled chicken meat

BACKGROUND

Bacterial cellulose (BC) is a fiber substance produced by microbial fermentation. It is widely used in the food preservation industry because of its extremely pure texture, high crystallinity and high biocompatibility. In the present study, bacterial cellulose/thyme essential oil (BC/TEO-E) with antibacterial and fresh-keeping functions was prepared by ultrasonic treatment of modified bacterial cellulose for encapsulation of thyme essential oil, which effectively inhibited the spoilage of chilled chicken.

RESULTS

The purified BC, produced by Acetobacter xylinum ATCC 53524, was ultrasonically treated wih different times (0, 30, 60 and 90 min). Transmission electron microscopy, scanning electron microscopy, Fourier transformed infrared spectroscopy, X-ray diffraction, differential scanning calorimetry and zeta potential were used to characterize the structure of BC after ultrasound, showing that BC, treated for 30 min, had the optimal fiber structure, crystallinity (85.8%), thermal stability (347.77 °C) and solution stability (-26.63 ± 1.96 mV). BC/TEO-E was prepared by a homogenizer for the preservation of chilled chicken. Optical microscopy indicated that the BC/TEO-E prepared by 0.5% BC had optimal dispersion and stability, and even no delamination was observed in the emulsion. Compared with other groups (control, 0.5% BC and Tween-E), the total number of colonies and coliforms in chilled chicken treated with 0.5% BC/TEO-E was the lowest during the whole storage period (12 days), indicating that it can effectively inhibit bacterial growth. In addition, total volatile base nitrogen (TVB-N), thiobarbituric acid reactive substances, pH and drip loss results showed that 0.5% BC/TEO-E could effectively inhibit the spoilage of chilled chicken compared to the other treatment groups.

CONCLUSION

All of the results acquired in the present study indicate that BC/TEO-E has a potential application in chilled chicken preservation. © 2024 Society of Chemical Industry.

Using bacterial cellulose to bridge covalent and physical crosslinks in hydrogels for fabricating multimodal sensors

Network optimization is vital for the polysaccharide based hydrogels with multiple crosslinks. In this study, we developed a 'two-step' strategy to activate synergistic effect of chemical and physical crosslinks using a poly (vinyl alcohol) (PVA)/bacterial cellulose (BC) hydrogel as a template. The BC nanofibers, on the one hand, acted as nucleating agents, participating in the crystallization of PVA, and on the other hand, were also involved in the formation of boronic ester bond, anchored with the PVA chains via chemical bonding. Therefore, the existence of BC nanofibers, as 'bridge', linked the crystalline regions and amorphous parts of PVA together, associating the two characteristic crosslinks, which was conducive to load transfer. The mechanical properties of resultant hydrogels, including the tensile elongation and strength, as well as fracture toughness, were significantly improved. Moreover, the dually cross-linked hydrogels possessed ionic conductivity, which was sensitive to the tensile deformation and environmental temperature. This study clarifies a unique role of BC nanofibers in hydrogels, and proposes an effective approach to construct multiple networks in the nanocellulose reinforced PVA hydrogels.

Semisolid medium internal phase emulsions stabilized by dendritic-like mushroom cellulose nanofibrils: Concentration effect and stabilization mechanism

Emulsions with reduced fat and natural stabilizers are currently prevalent. Herein, semisolid emulsions with an oil phase of 50 % were successfully prepared using cellulose nanofibrils from mushroom stipes as stabilizers. Cellulose nanofibrils obtained by high-pressure homogenization were dendritic-like and possessed a contact angle of 70.50 ± 0.41°. The rheological properties and stability of emulsions increased significantly as nanocellulose concentrations increased from 5 to 20 mg/mL, while nanocellulose at 25-30 mg/mL significantly reduced the storage stability and anti-lipid oxidation ability of emulsions. The microstructure of semisolid emulsions demonstrated that nanocellulose fibers at 20 mg/mL could stabilize emulsions by forming compact interfacial films around droplets and creating intensive bridging networks between neighboring droplets, while nanofibers at concentrations over 20 mg/mL easily clustered in the aqueous phase, making the droplets more susceptible to aggregation and demulsification. The results demonstrate that cellulose nanofibrils from mushroom byproducts have the potential to stabilize semisolid food-grade emulsions.

Preparation and functionalization of cellulose nanofibers using a naturally occurring acid and their application in stabilizing linseed oil/water Pickering emulsions

Finding efficient and environmental-friendly methods to produce and chemically modify cellulose nanofibers (CNFs) remains a challenge. In this study, lactic acid (LA) treatment followed by microfluidization was employed for the isolation and functionalization of CNFs. Small amounts of HCl (0.01, 0.1, and 0.2 M) were used alongside LA to intensify cellulose hydrolysis. FTIR spectroscopy and solid-state 13C NMR confirmed the successful functionalization of CNFs with lactyl groups during isolation, while SEM, AFM, and rheological tests revealed that the addition of HCl governed the fibers' sizes and morphology. Notably, the treatment with LA and 0.2 M HCl resulted in a more efficient defibrillation, yielding smaller nanofibers sizes (62 nm) as compared to the treatment with LA or HCl alone (90 and 108 nm, respectively). The aqueous suspension of CNFs treated with LA and 0.2 M HCl showed the highest viscosity and storage modulus. LA-modified CNFs were tested as stabilizers for linseed oil/water (50/50 v/v) emulsions. Owing to the lactyl groups grafted on their surface and higher aspect ratio, CNFs produced with 0.1 and 0.2 M HCl led to emulsions with increased stability (a creaming index increase of only 3 % and 1 %, respectively, in 30 days) and smaller droplets sizes of 23.4 ± 1.2 and 35.5 ± 0.5 μm, respectively. The results showed that LA-modified CNFs are promising stabilizers for Pickering emulsions.

Exploitation of function groups in cellulose materials for lithium-ion batteries applications

Cellulose, an abundant and eco-friendly polymer, is a promising raw material to be used for preparing energy storage devices such as lithium-ion batteries (LIBs). Despite the significance of cellulose functional groups in LIBs components, their structure-properties-application relationship remains largely unexplored. This article thoroughly reviews the current research status on cellulose-based materials for LIBs components, with a specific focus on the impact of functional groups in cellulose-based separators. The emphasis is on how these functional groups can enhance the mechanical, thermal, and electrical properties of the separators, potentially replacing conventional non-renewal material-derived components. Through a meticulous investigation, the present review reveals that certain functional groups, such as hydroxyl groups (-OH), carboxyl groups (-COOH), carbonyl groups (-CHO), ester functions (R-COO-R'), play a crucial role in improving the mechanical strength and wetting ability of cellulose-based separators. Additionally, the inclusion of phosphoric group (-PO3H2), sulfonic group (-SO3H) in separators can contribute to the enhanced thermal stability. The significance of comprehending the influence of functional groups in cellulose-based materials on LIBs performance is highlighted by these findings. Ultimately, this review explores the challenges and perspectives of cellulose-based LIBs, offering specific recommendations and prospects for future research in this area.

Effect of surface acetylation of chitin nanocrystals on the preparation and viscoelasticity of sunflower seed oil-in-water Pickering emulsions

Acetylated chitin nanocrystals (ChNCs) were used as stabilizer in this work to prepare sunflower seed oil-in-water emulsions for the morphological and rheological studies. The results revealed that the acetylation with moderate degree of substitution (0.38) reduced hydrophilicity and increased surface charge level of rod-like ChNCs, and as a result, significantly improved the emulsifying ability of ChNCs. At the same oil/water ratio and particle loading, the emulsions stabilized with the acetylated ChNCs had far smaller droplet size (∼3 μm) as compared to the emulsions stabilized with the pristine ChNCs (5-7 μm). The increased droplets numbers and improved surface coating level resulted in the enhanced viscous resistance and yield stress level, which improved the physical stability of the acetylated ChNC-stabilized emulsions as a result. In addition, the droplet clusters easily formed in this system, contributing to weak strain overshoot and decreased large-deformation sensitivity during dynamic shear flow. Therefore, the acetylated ChNC-stabilized system showed enhanced transient stress overshoot during startup flow and weakened thixotropy during cyclic ramp shear flow as compared to the pristine ChNC-stabilized system. The relationships between surface acetylation of ChNCs and flow behavior of emulsions were then established, which provide valuable information on the modulation of the ChNC-stabilized Pickering emulsions.

Nanocellulose from Cocoa Shell in Pickering Emulsions of Cocoa Butter in Water: Effect of Isolation and Concentration on Its Stability and Rheological Properties

There is a growing interest in developing new strategies to completely or partially replace cocoa butter in food and cosmetic products due to its cost and health effects. One of these alternatives is to develop stable emulsions of cocoa butter in water. However, incorporating cocoa butter is challenging as it solidifies and forms crystals, destabilizing the emulsion through arrested coalescence. Prevention against this destabilization mechanism is significantly lower than against coalescence. In this research, the rheological properties of nanocellulose from cocoa shell, a by-product of the chocolate industry, were controlled through isolation treatments to produce nanocellulose with a higher degree of polymerization (DP) and a stronger three-dimensional network. This nanocellulose was used at concentrations of 0.7 and 1.0 wt %, to develop cocoa butter in-water Pickering emulsion using a high shear mixing technique. The emulsions remained stable for more than 15 days. Nanocellulose was characterized using attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), hot water and organic extractives, atomic force microscopy (AFM), degree of polymerization (DP), and rheological analysis. Subsequently, the emulsions were characterized on days 1 and 15 after their preparation through photographs to assess their physical stability. Fluorescent and electronic microscopy, as well as rheological analysis, were used to understand the physical properties of emulsions.

Cellulose Nanofibril Stabilized Pickering Emulsion Templated Aerogel with High Oil Absorption Capacity

Nanocellulose-based aerogels, featuring a three-dimensional porous structure, are considered as a desirable green absorbent because of their exceptional absorption performance as well as the abundance and renewability of the raw material. However, these aerogels often require hydrophobic modification or carbonization, which is often environmentally harmful and energy-intensive. In this study, we introduce a Pickering-emulsion-templating approach to fabricate a cellulose nanofibril (CNF) aerogel with a hierarchical pore structure, allowing for high oil absorption capacity. n-Hexane-CNF oil-in-water Pickering emulsions are prepared as an emulsion template, which is further lyophilized to create a hollow microcapsule-based CNF (HM-CNF) aerogel with a density ranging from 1.3 to 6.1 mg/cm3 and a porosity of ≥99.6%. Scanning electron microscopy and Brunauer-Emmett-Teller analyses reveal the HM-CNF aerogel's hierarchical pore structure, originating from the CNF Pickering emulsion template, and also confirm the aerogel's very high surface area of 216.6 m2/g with an average pore diameter of 8.6 nm. Furthermore, the aerogel exhibits a maximum absorption capacity of 354 g/g and 166 g/g for chloroform and n-hexadecane, respectively, without requiring any surface modification or chemical treatment. These combined findings highlight the potential of the Pickering-emulsion-templated CNF aerogel as an environmentally sustainable and high-performance oil absorbent.

Surface Functionalization of Sugarcane-Bagasse-Derived Cellulose Nanocrystal for Pickering Emulsion Gel: Microstructural Properties and Stability Efficiency

An environmentally friendly Pickering stabilizer was developed by upcycling sugarcane bagasse (SCB) into a cellulose nanocrystal (CNC), which was subjected to surface modification by using quaternary ammonium compound to enhance its amphiphilic characteristics. The changes in microstructural properties of modified cellulose nanocrystal (m-CNC), such as surface functional group, thermal stability, surface morphology, elemental composition, and particle size distribution were investigated. Results indicated the success of quaternary ammonium compound grafting with the presence of a trimethyl-alkyl chain on the cellulose structure, while the m-CNC preserves the needle-like nanoparticles in length of ~534 nm and width of ~20 nm. The colloidal profile of m-CNC-stabilized oil-water emulsion gels with different concentrations of m-CNC (1-5 wt%), and oil:water (O:W) ratios (3:7, 5:5, 7:3) were examined. The emulsion gel stability study indicated that the optimal concentration of m-CNC (3 wt%) was able to stabilize all the emulsion gels at different O:W ratios with an emulsion index of >80% for 3 months. It is the minimum concentration of m-CNC to form a robust colloidal network around the small oil droplets, leading to the formation of stable emulsion gels. The emulsion gel with O:W ratio (3:7) with 3 wt% of m-CNC rendered the best m-CNC-oil-droplets dispersion. The m-CNC effectively retained the size of oil droplets (<10 μm for 3 months storage) against coalescence and creaming by creating a steric barrier between the two immiscible phases. Furthermore, the emulsion gel exhibited the highest viscosity and storage modulus which was able to prevent creaming or sedimentation of the emulsion gels.

Pomelo peel derived nanocellulose as Pickering stabilizers: Fabrication of Pickering emulsions and their potential as sustained-release delivery systems for lycopene

Two kinds of nanocellulose (cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs) were synthesized from pomelo peels via a facile approach of TEMPO oxidation and sulfuric acid treatment respectively. The FTIR results illustrated that hemicelluloses and lignin were completely removed from the pomelo peel cellulose substrate. The obtained CNFs and CNCs possessed a uniform morphology and nanoscale particle size. The stability of CNF-based Pickering emulsions was higher than that of emulsions stabilized with CNCs, due to the formation of gel structure induced by the CNFs' longer fibrils. Increased oil fractions enhanced the viscoelasticity of CNF-based Pickering emulsions. The in vitro digestion results suggested that increased oil fractions decreased the lipolysis degree, as a result of the larger droplet size and higher viscoelasticity of emulsion. The release of lycopene showed a trend similar to that of FFA release, suggesting that higher oil fractions were beneficial for controlling lycopene release during gastrointestinal digestion.

Eco-friendly and effective antimicrobial Melaleuca alternifolia essential oil Pickering emulsions stabilized with cellulose nanofibrils against bacteria and SARS-CoV-2

Melaleuca alternifolia essential oil (MaEO) is a green antimicrobial agent suitable for confection eco-friendly disinfectants to substitute conventional chemical disinfectants commonly formulated with toxic substances that cause dangerous environmental impacts. In this contribution, MaEO-in-water Pickering emulsions were successfully stabilized with cellulose nanofibrils (CNFs) by a simple mixing procedure. MaEO and the emulsions presented antimicrobial activities against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Moreover, MaEO deactivated the SARS-CoV-2 virions immediately. FT-Raman and FTIR spectroscopies indicate that the CNF stabilizes the MaEO droplets in water by the dipole-induced-dipole interactions and hydrogen bonds. The factorial design of experiments (DoE) indicates that CNF content and mixing time have significant effects on preventing the MaEO droplets' coalescence during 30-day shelf life. The bacteria inhibition zone assays show that the most stable emulsions showed antimicrobial activity comparable to commercial disinfectant agents such as hypochlorite. The MaEO/water stabilized-CNF emulsion is a promissory natural disinfectant with antibacterial activity against these bacteria strains, including the capability to damage the spike proteins at the SARS-CoV-2 particle surface after 15 min of direct contact when the MaEO concentration is 30 % v/v.

Large-Scale Preparation of Carboxylated Cellulose Nanocrystals and Their Application for Stabilizing Pickering Emulsions

Cellulose nanocrystals (CNCs) with varied unique properties have been widely used in emulsions, nanocomposites, and membranes. However, conventional CNCs for industrial use were usually prepared through acid hydrolysis or heat-controlled methods with sulfuric acid. This most commonly used acid method generally suffers from low yields, poor thermal stability, and potential environmental pollution. Herein, we developed a high-efficiency and large-scale preparation strategy to produce carboxylated cellulose nanocrystals (Car-CNCs) via carboxymethylation-enhanced ammonium persulfate (APS) oxidation. After carboxymethylation, the wood fibers could form unique "balloon-like" structures with abundant exposed hydroxy groups, which facilitated exfoliating fibril bundles into individual nanocrystals during the APS oxidation process. The production process under controlled temperature, time period, and APS concentrations was optimized and the resultant Car-CNCs exhibited a typical structure with narrow diameter distributions. In particular, the final Car-CNCs exhibited excellent thermal stability (≈346.6 °C) and reached a maximum yield of 60.6%, superior to that of sulfated cellulose nanocrystals (Sul-CNCs) prepared by conventional acid hydrolysis. More importantly, compared to the common APS oxidation, our two-step collaborative process shortened the oxidation time from more than 16 h to only 30 min. Therefore, our high-efficiency method may pave the way for the up-scaled production of carboxylated nanocrystals. More importantly, Car-CNCs show potential for stabilizing Pickering emulsions that can withstand changeable environments, including heating, storage, and centrifugation, which is better than the conventional Sul-CNC-based emulsions.

Improvement of the emulsifying properties of mixed emulsifiers by optimizing ultrasonic-assisted processing

Optimizing ultrasound (ULD)-assisted flavonoid modification is an important component of enhancing its application potential. In this work, diverse flavonoids, such as quercetin (Que), apigenin (Api), and morin (Mor), were used to modify protein in myofibrillar protein (MP)/cellulose nanocrystal (CN) complexes using ULD-assisted method. Compared with the MP/CNs group, the triiodide contents of MP-Que/CNs, MP-Api/CNs, and MP-Mor/CNs increased by 1175.84%, 479.05%, and 2281.50% respectively. The findings revealed that the actual intensity of ULD was drastically reduced by the molecular weight decrease of these flavonoids. For olive oil emulsions prepared with mixed emulsifiers, the low interfacial diffusion rates (0.03 mN·m·s-1/2) and weak emulsifying activity (8.33 m2/g) of the MP/CN complexes were significantly improved by the flavonoids after ULD-assisted treatment. Notably, the emulsions prepared using MP-Api/CNs contained smaller oil droplets and exhibited better emulsifying properties, compared to emulsions prepared with MP-Mor/CNs or MP-Que/CNs. This study is essential for ULD-assisted treatment since the processing impact may be increased by choosing the most suitable flavonoid.

Thermomechanically micronized sugar beet pulp: Emulsification performance and the contribution of soluble elements and insoluble fibrous particles

In this work, thermomechanically micronized sugar beet pulp (MSBP), a micron-scaled plant-based byproduct comprised of soluble elements (∼40 wt%) and insoluble fibrous particles (IFPs, ∼60 wt%), was used as a sole stabilizer for oil-in-water emulsion fabrication. The influence of emulsification parameters on the emulsifying properties of MSBP was investigated, including emulsification techniques, MSBP concentration, and oil weight fraction. High-speed shearing (M1), ultrasonication (M2), and microfludization (M3) were used to fabricate oil-in-water emulsions (20% oil) with 0.60 wt% MSBP as stabilizer, in which the d_4,3 value was 68.3, 31.5, and 18.2 μm, respectively. Emulsions fabricated by M2 and M3 (higher energy input) were more stable than M1 (lower energy input) during long-term storage (30 days) as no significant increase of d_4,3. As compared to M1, the adsorption ratio of IFPs and protein was increased from ∼0.46 and ∼0.34 to ∼0.88 and ∼0.55 by M3. Fabricated by M3, the creaming behavior of emulsions was completely inhibited with 1.00 wt% MSBP (20% oil) and 40% oil (0.60 wt% MSBP), showing a flocculated state and could be disturbed by sodium dodecyl sulfate. The gel-like network formed by IFPs could be strengthened after storage as both viscosity and module were significantly increased. During emulsification, the co-stabilization effect of the soluble elements and IFPs enabled a compact and hybrid coverage onto the droplet surface, which acted as a physical barrier to endow the emulsion with robust steric repulsion. Altogether, these findings suggested the feasibility of using plant-based byproducts as oil-in-water emulsion stabilizers.

Astaxanthin-Loaded Pickering Emulsions Stabilized by Nanofibrillated Cellulose: Impact on Emulsion Characteristics, Digestion Behavior, and Bioaccessibility

Astaxanthin (AX) is one of the major bioactives that has been found to have strong antioxidant properties. However, AX tends to degrade due to its highly unsaturated structure. To overcome this problem, a Pickering O/W emulsion using nanofibrillated cellulose (NFC) as an emulsifier was investigated. NFC was used because it is renewable, biodegradable, and nontoxic. The 10 wt% O/W emulsions with 0.05 wt% AX were prepared with different concentrations of NFC (0.3-0.7 wt%). After 30 days of storage, droplet size, ζ-potential values, viscosity, encapsulation efficiency (EE), and color were determined. The results show that more stable emulsions are formed with increasing NFC concentrations, which can be attributed to the formulation of the NFC network in the aqueous phase. Notably, the stability of the 0.7 wt% NFC-stabilized emulsion was high, indicating that NFC can improve the emulsion's stability. Moreover, it was found that fat digestibility and AX bioaccessibility decreased with increasing NFC concentrations, which was due to the limitation of lipase accessibility. In contrast, the stability of AX increased with increasing NFC concentrations, which was due to the formation of an NFC layer that acted as a barrier and prevented the degradation of AX during in vitro digestion. Therefore, high concentrations of NFC are useful for functional foods delivering satiety instead of oil-soluble bioactives.

Utilization of different wood-based microfibril cellulose for the preparation of reinforced hydrophobic polymer composite films via Pickering emulsion: A comparative study

Pickering emulsion is a promising strategy for the preparation of hydrophobic polymer composite using hydrophilic nanocellulose. Herein, two types of microfibril cellulose, pure mechanical pretreated microfibril cellulose (P-MFC) and Deep eutectic solvents pretreated microfibril cellulose (DES-MFC), were used to fabricate reinforced hydrophobic polystyrene (PS) composites (MFC/PS) with the aid of Pickering emulsion. The results showed that both oil/water ratio and the content as well as surface hydrophilicity of MFC were playing an important role in emulsifying capacity. 8 % MFC/PS emulsion showed the smallest and most uniform emulsion droplets which is similar to nanofibril cellulose (NFC)/PS at the oil/water ratio of 3:1. The mechanical performance of MFC/PS composites verified that the reinforcement effect was closely related to the emulsifying capacity of MFC. Specially, when the content of P-MFC was 8 wt%, the composite exhibited the best mechanical properties with the tensile strength of 44.7 ± 4.4 MPa and toughness of 1162 ± 52.8 kJ/m³ and Young's modulus of 13.5 ± 0.8 GPa, which was comparable to NFC/PS composite. Moreover, the effective enhancement role of P-MFC in hydrophobic polymethyl methacrylate and polycarbonate composites were also realized via Pickering emulsion strategy. Overall, this work constituted a proof of concept of the potential application of P-MFC in nano-reinforced hydrophobic composite.

Cellulose Nanofiber-Coated Perfluoropentane Droplets: Fabrication and Biocompatibility Study

Purpose

To study the effect of cellulose nanofiber (CNF)-shelled perfluoropentane (PFP) droplets on the cell viability of 4T1 breast cancer cells with or without the addition of non-encapsulated paclitaxel.

Methods

The CNF-shelled PFP droplets were produced by mixing a CNF suspension and PFP using a homogenizer. The volume size distribution and concentration of CNF-shelled PFP droplets were estimated from images taken with an optical microscope and analyzed using Fiji software and an in-house Matlab script. The thermal stability was qualitatively assessed by comparing the size distribution and concentration of CNF-shelled PFP droplets at room temperature (~22°) and 37°C. The cell viability of 4T1 cells was measured using a 3-[4,5-dimethylthiazol-2yl]-2,5-diphenyltetrazolium bromide (MTT) assay. Additionally, a hemolysis assay was performed to assess blood compatibility of CNF-shelled PFP droplets.

Results

The droplet diameter and concentration of CNF-shelled PFP droplets decreased after 48 hours at both room temperature and 37°C. In addition, the decrease in concentration was more significant at 37°C, from 3.50 ± 0.64×10⁶ droplets/mL to 1.94 ± 0.10×10⁶ droplets/mL, than at room temperature, from 3.65 ± 0.29×10⁶ droplets/mL to 2.56 ± 0.22×10⁶ droplets/mL. The 4T1 cell viability decreased with increased exposure time and concentration of paclitaxel, but it was not affected by the presence of CNF-shelled PFP droplets. No hemolysis was observed at any concentration of CNF-shelled PFP droplets.

Conclusion

CNF-shelled PFP droplets have the potential to be applied as drug carriers in ultrasound-mediated therapy.

Review of Functional Aspects of Nanocellulose-Based Pickering Emulsifier for Non-Toxic Application and Its Colloid Stabilization Mechanism

In the past few years, the research on particle-stabilized emulsion (Pickering emulsion) has mainly focused on the usage of inorganic particles with well-defined shapes, narrow size distributions, and chemical tunability of the surfaces such as silica, alumina, and clay. However, the presence of incompatibility of some inorganic particles that are non-safe to humans and the ecosystem and their poor sustainability has led to a shift towards the development of materials of biological origin. For this reason, nano-dimensional cellulose (nanocellulose) derived from natural plants is suitable for use as a Pickering material for liquid interface stabilization for various non-toxic product formulations (e.g., the food and beverage, cosmetic, personal care, hygiene, pharmaceutical, and biomedical fields). However, the current understanding of nanocellulose-stabilized Pickering emulsion still lacks consistency in terms of the structural, self-assembly, and physio-chemical properties of nanocellulose towards the stabilization between liquid and oil interfaces. Thus, this review aims to provide a comprehensive study of the behavior of nanocellulose-based particles and their ability as a Pickering functionality to stabilize emulsion droplets. Extensive discussion on the characteristics of nanocelluloses, morphology, and preparation methods that can potentially be applied as Pickering emulsifiers in a different range of emulsions is provided. Nanocellulose's surface modification for the purpose of altering its characteristics and provoking multifunctional roles for high-grade non-toxic applications is discussed. Subsequently, the water-oil stabilization mechanism and the criteria for effective emulsion stabilization are summarized in this review. Lastly, we discuss the toxicity profile and risk assessment guidelines for the whole life cycle of nanocellulose from the fresh feedstock to the end-life of the product.

Characterization of Physicochemical Properties of Oil-in-Water Emulsions Stabilized by Tremella fuciformis Polysaccharides

In this paper, emulsions stabilized by Tremella fuciformis polysaccharides (TFP) were prepared and the physiochemical properties were assessed. Results showed that the TFP emulsions illustrated the highest emulsifying activity (EAI) and emulsifying stability (ESI) when the concentration of TFP and oil were 0.8% and 10% (wt%). The higher pH value was in favor of the emulsifying properties, while the addition of NaCl impaired the stability, and the greater the concentration, the lower the EAI and ESI. Besides, the emulsifying and rheological properties and stability analysis were evaluated in comparison with gum arabic, pectin, and carboxymethyl cellulose emulsions. It was discovered that TFP illustrated better storage and freeze-thaw stability, which was proved by the result of zeta-potential and particle size. The rheological measurement revealed that all the emulsions behaved as pseudoplastic fluids, while TFP displayed a higher viscosity. Meanwhile, TFP emulsions tended to form a more stable network structure according to the analysis of the parameters obtained from the Herschel–Bulkley model. FTIR spectra suggested that the O-H bond could be destructed without the formation of new covalent bonds during the emulsion preparation. Therefore, this study would be of great importance for the research of emulsions stabilized by TFP as a natural food emulsifier.

Mapping hierarchical networks of poly(vinyl alcohol)/cellulose nanofiber composite hydrogels via viscoelastic probes

Discriminating the roles of different networks in the multiply cross-linked hydrogels is vital to optimize their overall performance. Poly(vinyl alcohol)/cellulose nanofiber composite hydrogels were used as template for the study. Three types of characteristic networks, including chemical network cross-linked with boronic ester bonds, physical network cross-linked with microcrystallites, and coexistence of these two networks, were constructed in the system, and the viscoelastic responses were used to detect the characteristic relaxation behavior of those networks. The physical network is more sensitive to stress-induced deformation, whereas the chemical network more sensitive to strain-induced one. The former has lower level of viscous dissipation and higher level of elastic storage as compared to the latter, and dominates linear viscoelasticity of hydrogels as the two networks coexist. Their synergistic effect can be well defined by the scaling behavior of hysteretic work. This work proposes an interesting method of probing networks in the multiply cross-linked hydrogels.

Stabilization of Pickering emulsions via synergistic interfacial interactions between cellulose nanofibrils and nanocrystals

Nanocellulose is a promising stabilizer for industrial emulsions that offers the advantages of sustainability, biodegradability and nontoxicity. Emulsions prepared using cellulose nanofibrils (CNF) and nanocrystals (CNCs) in mildly acidic lithium bromide trihydrate (MALBTH) were characterized in this study. At fixed CNCs concentration (0.3 wt%), increasing the CNF content from 0 to 0.9 wt% clearly influenced the stability and microstructure of Pickering emulsions. The Oil droplets size decreased and stabilized with increasing CNF loading. This emulsification behavior was attributed to the irreversible adsorption of CNCs on the surface of the oil droplets and the formation of a dense CNF network in the aqueous phase, thereby improving the emulsion stability. The universal applicability of the proposed method was verified using cyclohexane and edible olive oil as oil phases. Overall, this study may provide a novel means of producing all-natural, low-oil, food-grade emulsions with adjustable stability.

A rheological investigation of oil-in-water Pickering emulsions stabilized by cellulose nanocrystals

HYPOTHESIS

High and medium internal phase Pickering emulsions stabilized with cellulose nanocrystals (CNCs) exhibited very different performance compared to their peers stabilized with a surfactant. In this paper, we ascribed the difference to the formation of hydrogen bonding and van der Waals interactions between the CNC nanoparticles on adjacent oil droplets.

EXPERIMENTS

Rheological properties of CNC-stabilized oil-in-water medium internal phase emulsions (MIPEs, oil content = 65% v/v) and high internal phase emulsions (HIPEs, oil content = 80% v/v) were comprehensively characterized using both oscillatory and rotational tests.

FINDINGS

It was found that in the MIPEs, the van der Waals and hydrogen bonding interactions dominate the emulsion properties, whereas the compact structure of oil droplets plays a more important role in the HIPEs. CNC concentration in the aqueous phase also affects the emulsion properties, especially for the HIPEs, and the results can be correlated to the stabilization mechanisms we previously reported. The information from these tests provides a much-needed guidance for the practical application of CNC-stabilized emulsions.

Microencapsulated phase change material via Pickering emulsion stabilized by cellulose nanofibrils for thermal energy storage

A phase change material (PCM) has an ability to store and release a large amount of energy in a wide range of temperature by the latent heat of fusion upon melting and crystallization. Microencapsulation may protect PCM from undesirable reaction and leaching. Herein, we report the microencapsulation of n-hexadecane via oil-in-water Pickering emulsions stabilized by non-chemically modified cellulose nanofibrils (CNF). The maximum size of PCM-CNF microcapsules was 12 ± 3.4 μm in diameter. The surface coverage of the microcapsule by CNF was as high as 67%, consistent with porous morphology of the freeze-dried microcapsules. With 59% PCM loading, the PCM-CNF microcapsule exhibited 132.5 and 141.1 J/g as stored and released thermal energy, respectively. The microcapsule slurry showed a reversible change in storage modulus by one order of magnitude across the transition temperature of n-hexadecane. Combined results demonstrate the successful microencapsulation of PCM via CNF-based Pickering emulsions for a sustainable thermal energy storage material.

Preparation and Characterization of Pickering Emulsions with Modified Okara Insoluble Dietary Fiber

Modified okara insoluble dietary fiber (OIDF) has attracted great interest as a promising Pickering emulsifier. At present, the modification methods are mainly physicochemical methods, and the research on microbial modified OIDF as stabilizer is not clear. In this work, modified OIDF was prepared by yeast Kluyveromyces marxianus fermentation. The potential of modified OIDF as a Pickering emulsifier and the formation and stability of OIDF-Pickering emulsions stabilized by modified OIDF were characterized, respectively. The results showed that the specific surface area, hydrophilicity, and electronegativity of the modified OIDF were all enhanced compared with the unmodified OIDF. The existence of the network structure between droplets is the key to maintain the stability of the emulsions, as indicated by Croy-Scanning Electron Microscope (Croy-SEM) and rheological properties measurements. The stability of OIDF-Pickering emulsions was evaluated in terms of storage time, centrifugal force, pH value, and ionic strength (NaCl). Moreover, the OIDF-Pickering emulsions stabilized by modified OIDF showed better stability. These results will contribute to the development of efficient OIDF-based emulsifiers, expand the application of emulsions in more fields, and will greatly improve the high-value utilization of okara by-products.

A Superhydrophobic Moso Bamboo Cellulose Nano-Fibril Film Modified by Dopamine Hydrochloride

The moso bamboo fiber powder was used as raw material to prepare cellulose nano-fibril films, 5% of polyvinyl alcohol solution was used as a structural reinforcement agent, dopamine hydrochloride (DA) was used as a surface adhesive, and hexadecyl trimethoxy silane was used as a surface modifier. The superhydrophobic films were prepared by vacuum filtration and impregnation. The results showed that the water contact angle on the surface of the film could reach 156°. The microstructure and chemical composition of the film surface was further studied by scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FTIR), and roughness measurement The scanning electron microscopy images showed that the nanofibers on the surface of Cellulose nanofibers film were arranged and randomly distributed, thus forming a dense network interwoven structure. In PDA hydrophobic modification solution, an Hexadecyltrimethoxysilane was hydrolyzed to a hexadecyl silanol to obtain the polar terminal hydroxyl of Hexadecyl silanol molecule. The -OCH3 terminal group of HDTMS reacted with hydroxyl/H₂O to form a silanol (Si-OH) bond and further condensed to form a Si-O-Si network. In addition, due to the hydrophilicity of the surface of the nano cellulose film, a large amount of—OH was adsorbed on the surface of the nano cellulose film, resulted in the chemical connection between cetyl groups, thus realized the grafting of cetyl long-chain alkyl groups onto the fibers of the nano cellulose film.The film showed good self-cleaning and waterproof properties, which can be widely used in wet environment packaging and building.

Water-in-water Pickering emulsions stabilized by the starch nanocrystals with various surface modifications

HYPOTHESIS

Using the platelet-like starch nanocrystals (SNCs) to stabilize emulsions is attractive because as-prepared emulsions have promising applications in cosmetics and food fields. Limited studies mainly focus on the oil-in-water system, and another important system, the water-in-water emulsions stabilized by SNCs, has not yet been unveiled.

EXPERIMENTS

Two surface modification strategies, crosslinking and acetylation, were applied to tune surface property and aggregation of SNCs, and a common all-aqueous system (dextran/poly(ethylene glycol)) was used here as template. The viscoelasticity and morphology of emulsions were studied in terms of the SNC loadings and polymer ratios.

FINDINGS

Crosslinking results in aggregation of SNCs, and the particle size increases (from 110 nm to 370 nm) with increased levels of substitution. This favors improving emulsifying ability of particles. Acetylation decreases the particle size (∼90 nm) and weakens the affinity of SNCs to the two aqueous phases, improving the emulsifying efficiency of SNCs. More intriguingly, the two emulsion systems show different phase inversion behaviors. The depletion-stabilization mechanism for the cross-linked SNCs and the diffusion-controlled mechanism for the acetylated SNCs are proposed using the emulsion viscoelasticity as probe. This study makes a comprehensive insight into the regulation of water-in-water emulsion morphology and types with the platelet-like SNCs.