Colloids and Interfaces

9 pages, 1292 KiB

Open AccessFeature PaperArticle

Exploring the Feasibility of a Microchip Laser Ablation Method for the Preparation of Biopolymer-Stabilized Gold Nanoparticles: Case Studies with Gelatin and Collagen

by Nazgul Assan, Tomoyuki Suezawa, Yuta Uetake, Yumi Yakiyama, Michiya Matsusaki and Hidehiro Sakurai

Colloids Interfaces 2025, 9(4), 42; https://doi.org/10.3390/colloids9040042 - 20 Jun 2025

Abstract

Introducing small-sized metal nanoparticles directly into biopolymers susceptible to thermal and chemical stimulations remains a significant challenge. Recently, we showed a novel approach to fabricating gold nanoparticles through pulsed laser ablation in liquid (PLAL) using a microchip laser (MCL). Despite its lower pulse [...] Read more.

Introducing small-sized metal nanoparticles directly into biopolymers susceptible to thermal and chemical stimulations remains a significant challenge. Recently, we showed a novel approach to fabricating gold nanoparticles through pulsed laser ablation in liquid (PLAL) using a microchip laser (MCL). Despite its lower pulse energy compared to conventional lasers, this technique demonstrates high ablation efficiency, offering the potential to produce composites without compromising the distinctive structure of biopolymers. As a proof of concept, we successfully generated gelatin-stabilized gold nanoparticles with a smaller size (average diameter of approximately 4 nm), while preserving the unchanged circular dichroism (CD) spectra, indicating the retention of gelatin’s unique structure. Extending this technique to the preparation of type I collagen-stabilized gold nanoparticles yielded non-aggregated nanoparticles, although challenges in yield still persist. These results highlight the potential of the microchip laser ablation technique for producing metal nanoparticles within a vulnerable matrix. Full article

(This article belongs to the Special Issue State of the Art of Colloid and Interface Science in Asia)

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17 pages, 2097 KiB

Open AccessArticle

Study on the Optical Properties and Lattice Thermal Conductivity of Ti₂AlB₂

by Shengzhao Wang, Jinfan Song and Bin Liu

Colloids Interfaces 2025, 9(3), 41; https://doi.org/10.3390/colloids9030041 - 19 Jun 2025

Abstract

In this paper, the optical properties and lattice thermal conductivity of Ti₂AlB₂ were studied by first-principles calculations. The real part of the dielectric constant, ε₁, attains a significant value of 47.26 at 0.12 eV, indicating strong polarization capabilities [...] Read more.

In this paper, the optical properties and lattice thermal conductivity of Ti₂AlB₂ were studied by first-principles calculations. The real part of the dielectric constant, ε₁, attains a significant value of 47.26 at 0.12 eV, indicating strong polarization capabilities and energy storage capacity. Regarding optical properties, Ti₂AlB₂ exhibits significant absorption peaks at photon energies of 4.19 eV, 6.78 eV, and 10.61 eV, and 14.32 eV, with absorption coefficients of 184,168.1 cm⁻¹, 228,860.8 cm⁻¹, 366,350.8 and 303,440.6 cm⁻¹, indicating a strong absorption capacity. The loss function exhibits peaks at 19.80 eV and the refractive index reaches a maximum of 8.30 at 0.01 eV. Reflectivity is notably higher in the 0–5 eV range, exceeding 44%, which demonstrates excellent reflective properties. This suggests that Ti₂AlB₂ has potential as an optical coating material across certain frequency bands. The lattice thermal conductivity of Ti₂AlB₂ is obtained at 27.2 W/(m·K). The phonon relaxation time is greater in the low-frequency region, suggesting that phonons have a longer duration of action during the heat transport process, which may contribute to higher thermal conductivity. Although the phonon group velocity is generally low, several factors influence thermal conductivity, including phonon relaxation time and Grüneisen parameters. The high Grüneisen parameter of Ti₂AlB₂ indicates strong anharmonic vibrations, which may enhance phonon scattering and consequently reduce thermal conductivity. However, Ti₂AlB₂ still exhibits some lattice thermal conductivity, suggesting that the contributions of phonon relaxation time and group velocity to its thermal conductivity may be more significant. The unique optical properties and thermal conductivity of Ti₂AlB₂ indicate its potential applications in optical coatings and high-temperature structural materials. Full article

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22 pages, 2616 KiB

Open AccessArticle

Interactions in Lidocaine-Carboxylic Acid-Based Deep Eutectic Solvents: Implications for Cobalt Extraction

by Zaichao Dong, Rong Zhang, Jiyan Chen, Chenghao Qu, Xin Wang, Chen Cong, Yang Liu and Lingyun Wang

Colloids Interfaces 2025, 9(3), 40; https://doi.org/10.3390/colloids9030040 - 18 Jun 2025

Abstract

The limited understanding of intermolecular interactions in deep eutectic solvents (DESs) has restricted their rational design and broader application. In this study, a series of hydrophobic DESs (HDESs) were prepared using lidocaine as the hydrogen bond acceptor and various carboxylic acids as hydrogen [...] Read more.

The limited understanding of intermolecular interactions in deep eutectic solvents (DESs) has restricted their rational design and broader application. In this study, a series of hydrophobic DESs (HDESs) were prepared using lidocaine as the hydrogen bond acceptor and various carboxylic acids as hydrogen bond donors. Their physicochemical properties, including density, viscosity, and thermal stability, were systematically characterized. Interactions between components were evaluated through excess molar volume, viscosity deviation, and Grunberg–Nissan parameters. Strong hydrogen bonding between lidocaine and carboxylic acids was confirmed, which weakened with increasing alkyl chain length of the acids. Furthermore, as the acid content in the mixture increased, lidocaine’s ability to disrupt the intrinsic hydrogen-bonding network of the carboxylic acids decreased, thereby weakening the hydrogen bonding interactions between the components. The extraction capability of the HDESs for cobalt ions was evaluated in aqueous systems. Cobalt, a key material in lithium-ion batteries and advanced alloys, is in rising demand due to clean energy development. The lidocaine/decanoic acid (1:2) system exhibited nearly 100% extraction efficiency, surpassing conventional extractants. The hydrophobic nature of the HDESs facilitated effective phase separation and reduced solvent loss. These findings provide theoretical insights and design principles for developing high performance HDESs tailored for environmentally friendly metal recovery, particularly in battery recycling and treatment of industrial wastewater. Full article

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32 pages, 3594 KiB

Open AccessArticle

Interaction of SBA-15 with Dilute Acetic Acid and Ammonia

by Marta Kalbarczyk, Sebastian Skupiński, Daniel Kamiński and Marek Kosmulski

Colloids Interfaces 2025, 9(3), 39; https://doi.org/10.3390/colloids9030039 - 15 Jun 2025

Abstract

The SAXS pattern and pore volume of SBA-15 are not affected by aging SBA-15 with water, dilute acetic acid, and ammonia up for to 1 month, while the specific surface area is substantially depressed in interactions with basic solutions. The SEM images indicate [...] Read more.

The SAXS pattern and pore volume of SBA-15 are not affected by aging SBA-15 with water, dilute acetic acid, and ammonia up for to 1 month, while the specific surface area is substantially depressed in interactions with basic solutions. The SEM images indicate pits on the side surfaces of SBA-15 particles in interactions with basic solutions. Aging of SBA-15 in ammonia solutions results in cavities formed by the collapse of walls between neighboring hexagonal channels in the SBA-15. This phenomenon is discussed with a special emphasis on its possible effect on the potentiometric titration curves. Especially, a standard procedure, in which the SSA measured before the titration is used to calculate the σ₀, is compared with a modified procedure, in which the SSAs measured before and after the titration are used to estimate the SSA for each data point separately. Full article

(This article belongs to the Special Issue Ten Years Without Nikola Kallay)

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14 pages, 2418 KiB

Open AccessArticle

Durable and High-Efficiency Air Filtration by Superamphiphobic Silica Composite Aerogel

by Qiang Yu, Yuxin Mu, Pengfei Li, Wenjun Zhou, Jianwen Zhang, Jinchao Li, Yong Wei and Shanlin Wang

Colloids Interfaces 2025, 9(3), 38; https://doi.org/10.3390/colloids9030038 - 14 Jun 2025

Abstract

The escalating industrial emissions have dramatically increased airborne particulate matter (PM), particularly submicron particles (PM0.3), creating substantial health risks through respiratory system penetration. Current fiber-based filtration systems predominantly relying on electrostatic adsorption mechanisms suffer from critical limitations, including insufficient efficiency, potential secondary contamination, [...] Read more.

The escalating industrial emissions have dramatically increased airborne particulate matter (PM), particularly submicron particles (PM0.3), creating substantial health risks through respiratory system penetration. Current fiber-based filtration systems predominantly relying on electrostatic adsorption mechanisms suffer from critical limitations, including insufficient efficiency, potential secondary contamination, and performance degradation in humid environments. We develop a flexible silica composite aerogel to overcome these challenges with customizable and exceptional superamphiphobicity. This composite aerogel exhibits high porosity of ~95% and robust compression Young’s modulus that reaches ~220 kPa at 50% strain even after 1000 cycles. These features enable it to maintain a high filtration efficiency of ~98.52% for PM0.3, even after 50 cycles under traditional artificial simulation conditions. Significantly, a competitive filtration efficiency of ~97.9% is still performed in our composite aerogel at high humidity (water mist), high temperatures (50–250 °C), and corrosive solutions or atmospheres environments, revealing potential industrial applications. This work is expected to replace conventional air filtration materials and pave the way for various human protection and industrial production applications. Full article

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12 pages, 5789 KiB

Open AccessFeature PaperArticle

Composition-Dependent Optical Behavior of SnS_1−xSe_x Nanosheet Arrays Films

by Yongzhao Feng, Xinyi Lin, Xiaofang Lai and Jikang Jian

Colloids Interfaces 2025, 9(3), 37; https://doi.org/10.3390/colloids9030037 - 12 Jun 2025

Abstract

SnS_1−xSe_x (x = 0–1) films composed of vertically oriented nanosheet arrays were fabricated by vacuum thermal evaporation. The compositions of the SnS_1−xSe_x films were well tuned from SnS to SnSe, while their structures and morphology maintained the [...] Read more.

SnS_1−xSe_x (x = 0–1) films composed of vertically oriented nanosheet arrays were fabricated by vacuum thermal evaporation. The compositions of the SnS_1−xSe_x films were well tuned from SnS to SnSe, while their structures and morphology maintained the orthorhombic phase and the uniform nanosheet arrays. Se doping enhances the light absorption of the films, especially in the near-infrared region. The direct and indirect band gaps of the SnS_1−xSe_x (x = 0–1) nanosheet arrays films gradually changed from 1.26 eV and 1.12 eV for SnS to 1.00 eV and 0.79 eV for SnSe, respectively, with the change in compositions. The adjustable band gap makes these films promising candidates for infrared photodetectors and solar energy devices. Full article

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40 pages, 15594 KiB

Open AccessFeature PaperArticle

Selective Aggregation of Fine Spodumene from Quartz with Anionic Polyacrylamide Flocculant and Calcium Activator

by Danni Luo, Wei Sung Ng and George V. Franks

Colloids Interfaces 2025, 9(3), 36; https://doi.org/10.3390/colloids9030036 - 11 Jun 2025

Abstract

Fine spodumene particles are challenging to treat by froth flotation and are often discarded. An approach to recover the lithium-bearing mineral is to selectively aggregate fine spodumene into larger sizes that are amenable to recovery by flotation. This research investigated the aggregation behaviour [...] Read more.

Fine spodumene particles are challenging to treat by froth flotation and are often discarded. An approach to recover the lithium-bearing mineral is to selectively aggregate fine spodumene into larger sizes that are amenable to recovery by flotation. This research investigated the aggregation behaviour of spodumene and the gangue minerals K-feldspar and quartz, using commercially available anionic polyacrylamide flocculants. Calcium ions were used as activators that facilitated the selective adsorption of the carboxylate groups in the anionic flocculants onto the spodumene surface. The calcium ions decreased the magnitude of the negative zeta potential and reversed the zeta potential to positive for spodumene and K-feldspar, but not for quartz, below pH 10. Calcium concentrations of 312.5 g/t enhanced the adsorption of anionic polymers onto spodumene and K-feldspar, inducing aggregation, while quartz was aggregated only above 5000 g/t. Increasing the polymer concentration increased the aggregate size for spodumene and K-feldspar, but had little effect on quartz. In situ sizing and turbidity measurements indicated the optimal conditions for spodumene aggregation were 625 g/t of calcium and 63–84 g/t of the 58% anionic-charged polyacrylamide at pH 8.5. The sedimentation results showed limited separation due to quartz entrapment in the aggregates. Anionic polyacrylamide flocculants with calcium activators can aggregate fine spodumene particles. Full article

(This article belongs to the Special Issue Colloids and Interfaces in Mineral Processing)

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9 pages, 7852 KiB

Open AccessArticle

A Point-of-Care Diagnostic Method Using Desiccation Patterns of Blood Sessile Droplets

by Hui He, Lujia Xuan, Yihe Lin, Min Zhang, Junjie Mou and Ruoyang Chen

Colloids Interfaces 2025, 9(3), 35; https://doi.org/10.3390/colloids9030035 - 10 Jun 2025

Abstract

The evaporation of a blood sessile droplet on a solid substrate generates distinctive desiccation patterns. These patterns have been identified as a potential tool for interpreting the pathological information of donors, since their morphological features encode pathological indicators linked to blood-related disorders. We [...] Read more.

The evaporation of a blood sessile droplet on a solid substrate generates distinctive desiccation patterns. These patterns have been identified as a potential tool for interpreting the pathological information of donors, since their morphological features encode pathological indicators linked to blood-related disorders. We collected two representative sets of blood samples from anonymous patients: healthy donors (normal haematocrit) and anaemia patients (low haematocrit). Our real-time observations of the morphological evolution during desiccation reveal distinct differences in pattern development. The macroscopic analysis indicates that blood sessile droplets from anaemia patients with abnormally low haematocrit levels experience divergent morphological trajectories, forming cracking patterns distinguishable from those of healthy donors. Our microscopic comparisons show that the blood desiccation patterns of healthy donors exhibit a longer coronal region and greater deposit coverage in the central region than those of anaemia patients. Our further analysis correlates these morphological variations to the effects of the haematocrit level of blood samples on material redistribution. This work proposes a facile strategy for health diagnostics through blood desiccation pattern analysis, highlighting its potential as a foundation for diagnostic platforms. Full article

(This article belongs to the Special Issue Bubble and Drop 2025 (B&D 2025))

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19 pages, 5339 KiB

Open AccessFeature PaperArticle

Effect of the Comonomer Nature on the Cytotoxicity and Mechanical Properties of a Cryogel Based on Sodium 2-Acrylamido-2-methyl-1-propanesulfonate Copolymers

by Olga Iakobson, Elena Ivan’kova, Yulia Nashchekina, Gleb Vaganov, Svetlana Laishevkina and Natalia Shevchenko

Colloids Interfaces 2025, 9(3), 34; https://doi.org/10.3390/colloids9030034 - 28 May 2025

Abstract

Currently, for the treatment of corneal diseases (keratitis–corneal opacities), synthetic corneal analogs based on polymer films or hydrogels are being developed. The requirements for the material include biocompatibility, the presence of a developed system of macropores, transparency, rapid swelling, and mechanical strength. Here, [...] Read more.

Currently, for the treatment of corneal diseases (keratitis–corneal opacities), synthetic corneal analogs based on polymer films or hydrogels are being developed. The requirements for the material include biocompatibility, the presence of a developed system of macropores, transparency, rapid swelling, and mechanical strength. Here, with the aim of preparing such materials, a series of gels based on a copolymer of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMP) and 2-hydroxyethyl methacrylate (or vinyl acetate, or ethyl acrylate) were obtained using cryotropic gelation. It was shown that transparent cryogels can be obtained based on the sulfonate-containing comonomer 2-acrylamido-2-methyl-1-propanesulfonic acid at a crosslinking agent concentration of 2.2 mol.%, while the nature of the acrylate comonomer did not show any effect on transparency. It was found that when using AMP and ethyl acrylate, cryogels with a developed system of macropores with a diameter of 50 to 250 μm were formed, and the mechanical strength of such cryogels was sufficient for their subsequent use as corneal implants. Moreover, the PAMP hydrogel containing 2-hydroxyethyl methacrylate or ethyl acrylate units did not affect the viability of cells even after 1 month. Full article

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16 pages, 2174 KiB

Open AccessArticle

Polyvinylpyrrolidone-Capped CuInS₂ Colloidal Quantum Dots: Synthesis, Optical and Structural Assessment

by Oleg Korepanov, Olga Aleksandrova, Anna Botnar, Dmitrii Firsov, Zamir Kalazhokov, Demid Kirilenko, Polina Lemeshko, Vasilii Matveev, Dmitriy Mazing, Ivan Moskalenko, Alexander Novikov, Sviatlana Ulasevich and Vyacheslav Moshnikov

Colloids Interfaces 2025, 9(3), 33; https://doi.org/10.3390/colloids9030033 - 20 May 2025

Abstract

Ternary metal chalcogenide quantum dots (QDs), such as CuInS₂, have attracted significant attention due to their lower toxicity compared to binary counterparts containing cadmium or lead, making them promising candidates for biomedical imaging and solar energy applications. The surfactant choice is [...] Read more.

Ternary metal chalcogenide quantum dots (QDs), such as CuInS₂, have attracted significant attention due to their lower toxicity compared to binary counterparts containing cadmium or lead, making them promising candidates for biomedical imaging and solar energy applications. The surfactant choice is critical for controlling nanocrystal nucleation, growth kinetics, and functionalization. This directly affects the toxicity and applications of QDs. In this work, we report a synthesis protocol for PVP-capped CuInS₂ QDs in an aqueous solution. Using density functional theory (DFT) calculations, we predicted the coordination patterns of PVP on the CuInS₂ QDs surface, providing insights into the stabilization mechanism. The synthesized QDs were characterized using TEM, XRD, XPS, and FTIR to assess their morphology, chemical composition, and surface chemistry. The QDs exhibited dual photoluminescence (PL) maxima at 550 nm and 680 nm, attributed to defect-related emissions, making them suitable for cell imaging applications. Cytotoxicity studies and cell imaging experiments demonstrate the excellent biocompatibility and effective staining capabilities of the PVP-capped CuInS₂ QDs, highlighting their potential as fluorescent probes for long-term, multicolor cell imaging including two-photon microscopy. Full article

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15 pages, 1752 KiB

Open AccessReview

Sodium Alginate: A Green Biopolymer Resource-Based Antimicrobial Edible Coating to Enhance Fruit Shelf-Life: A Review

by Anshika Sharma and Arun K. Singh

Colloids Interfaces 2025, 9(3), 32; https://doi.org/10.3390/colloids9030032 - 19 May 2025

Abstract

Fruits are a significant source of natural nutrition for human health. However, the perishable nature and short shelf life of fruits lead to spoilage, nutrition safety challenges, and other substantial postharvest losses. Edible coatings have emerged as a novel approach in order to [...] Read more.

Fruits are a significant source of natural nutrition for human health. However, the perishable nature and short shelf life of fruits lead to spoilage, nutrition safety challenges, and other substantial postharvest losses. Edible coatings have emerged as a novel approach in order to enhance the shelf life of perishable fruits by forming a protective barrier against adverse environmental conditions and microbial infections. Sodium alginate is recognized as an excellent polysaccharide (derived from algae, seaweed, etc.) in the food industry for edible fruit coatings because of its non-allergic, biodegradable, non-toxic (safe for human health), inexpensive, and efficient gel/film-forming properties. However, the hydrophilicity of the polysaccharides is a significant concern to prevent the growth of mold and yeast. In recent years, various plant extracts (containing multiple bioactive compounds, including polyphenolic acids) and nanoparticles have been applied in sodium alginate-based edible films and fruit coatings to enhance antimicrobial activity. This review study summarized recent advancements in fabricating plant extracts incorporating sodium alginate-based films and coatings to enhance fruit shelf life. In addition, approaches to preparing edible films and the basic mechanism behind the role of coating materials in enhancing fruit shelf life are discussed. Moreover, the limitations associated with sodium alginate-based fruit coatings and films have been highlighted. Full article

(This article belongs to the Special Issue Food Colloids: 3rd Edition)

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14 pages, 6056 KiB

Open AccessArticle

Preparation of Colloidal Silver Triangular Nanoplates and Their Application in SERS Detection of Trace Levels of Antibiotic Enrofloxacin

by Cao Tuan Anh, Dao Tran Cao and Luong Truc-Quynh Ngan

Colloids Interfaces 2025, 9(3), 31; https://doi.org/10.3390/colloids9030031 - 16 May 2025

Abstract

Surface-enhanced Raman scattering (SERS) is a powerful technique for detecting trace amounts of chemicals due to its capacity to significantly amplify the Raman signal of the molecules of these substances. This is particularly relevant in food systems where monitoring antibiotic residues is critical [...] Read more.

Surface-enhanced Raman scattering (SERS) is a powerful technique for detecting trace amounts of chemicals due to its capacity to significantly amplify the Raman signal of the molecules of these substances. This is particularly relevant in food systems where monitoring antibiotic residues is critical for food safety. Traditional SERS substrates typically utilize colloidal silver nanospheres (AgNSs), but anisotropic silver nanoparticles with numerous sharp tips can further enhance SERS sensitivity, enabling lower detection limits suitable for food safety regulations. In this study, we describe a straightforward synthesis of colloidal silver triangular nanoplates (AgTNPls), featuring multiple sharp tips, using only four common reagents: silver nitrate, trisodium citrate, sodium borohydride (NaBH₄) and hydrogen peroxide (H₂O₂), all at room temperature. By carefully controlling the sequence of reagent addition, specifically introducing H₂O₂ after NaBH₄, we achieved a two-step synthesis. In the first step, AgNSs seeds form, and in the second, these seeds convert into AgTNPls, resulting in a colloid of relatively uniform AgTNPls with an edge length of approximately 52 nm. The resulting AgTNPls colloid, combined with an aluminum foil, produced an SERS substrate with high enhancement factor of 3.2 × 10⁹ (using rhodamine 6G as a test molecule). Applied to enrofloxacin (an antibiotic widely used in livestock and aquaculture) detection, this substrate achieved a detection limit as low as 0.39 µg/L (0.39 ppb), with enrofloxacin detectable at concentrations down to 5 µg/L. This highly sensitive SERS substrate holds great promise for rapid, accurate detection of antibiotic residues in food products, aiding regulatory compliance and food safety assurance. Full article

(This article belongs to the Special Issue Food Colloids: 3rd Edition)

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15 pages, 5965 KiB

Open AccessFeature PaperArticle

Gel Polymer Electrolytes with High Thermal Stability for Safe Lithium Metal Batteries

by Xianhui Chen, Xue Wang, Xing Li and Xing Xin

Colloids Interfaces 2025, 9(3), 30; https://doi.org/10.3390/colloids9030030 - 14 May 2025

Abstract

The poor thermal stability of polypropylene (PP) separators poses risks of electrolyte leakage and battery short-circuiting, limiting their application in lithium metal batteries (LMBs). To address these challenges, a gel polymer membrane was designed using polymer blending technology. This membrane effectively retains the [...] Read more.

The poor thermal stability of polypropylene (PP) separators poses risks of electrolyte leakage and battery short-circuiting, limiting their application in lithium metal batteries (LMBs). To address these challenges, a gel polymer membrane was designed using polymer blending technology. This membrane effectively retains the electrolyte, provides a stable environment, enhances thermal stability, and significantly decreases the risk of battery explosions and side reactions between the lithium metal and the electrolyte. Compared to commercial PP separators, the developed blend-type gel polymer electrolyte (b-GPE) demonstrates a superior performance, including structural stability at temperatures up to 150 °C and a high lithium-ion transference number (

t_{{L i}^{+}}

) of 0.513. Furthermore, a cell with a LiCoO₂ cathode operated at a 1 C rate retains 97.4% of its capacity after 300 cycles. After exposure to 120 °C, the b-GPE-120 demonstrates that its performance is comparable to that of the b-GPE, such as a

t_{{L i}^{+}}

of 0.506, a high electrolyte absorption rate, and a wide electrochemical window of 5.2 V. Full article

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30 pages, 6442 KiB

Open AccessArticle

Impact of Carrageenan-Based Encapsulation on the Physicochemical, Structural, and Antioxidant Properties of Freshwater Snail (Bellamya bengalensis) Protein Hydrolysates

by Anand Vaishnav, Naresh Kumar Mehta, Mocherla Bhargavi Priyadarshini, Soibam Khogen Singh, Pratap Chandra Acharya, Satyajeet Biswal, Harjeet Nath, Syed Arshad Hussain, Prasenjit Pal, Jham Lal, Nongthongbam Sureshchandra Singh and Bikash Kumar Pati

Colloids Interfaces 2025, 9(3), 29; https://doi.org/10.3390/colloids9030029 - 13 May 2025

Abstract

This study investigated the encapsulation of snail protein hydrolysates (SPHs) using carrageenan as a microencapsulating agent at concentrations of 1%, 2%, and 3%. SPHs were prepared from the soft tissue of freshwater snails (Bellamya bengalensis) through enzymatic hydrolysis using bromelain, resulting [...] Read more.

This study investigated the encapsulation of snail protein hydrolysates (SPHs) using carrageenan as a microencapsulating agent at concentrations of 1%, 2%, and 3%. SPHs were prepared from the soft tissue of freshwater snails (Bellamya bengalensis) through enzymatic hydrolysis using bromelain, resulting in a degree of hydrolysis of 48.05%. The encapsulation process was carried out using the spray-drying technique. Encapsulation with 3% carrageenan enhanced the yield, encapsulation efficiency (up to 84.96%), colloidal stability (up to −33.8 mV), and thermal stability (up to 75 °C). The particle size increased as the carrageenan concentration increased, reaching 206.9 nm at 3%, and the uniform polydispersity index (0.26) indicated stable encapsulation. While encapsulation reduces solubility and antioxidant activity (DPPH, FRAP, ABTS, and HRSA), it effectively protects SPH from environmental factors such as hygroscopicity and storage stability, thus maintaining high scavenging activity. Fourier transform infrared spectroscopy confirmed that carrageenan and SPH strongly interact. Scanning electron microscopy revealed that the particles had better shapes and smooth, cohesive surfaces. This study demonstrates the effectiveness of carrageenan as an encapsulating agent for SPH, enhancing its stability and bioactivity for potential applications in the food and nutraceutical industries as a bioactive additive and offering an alternative to conventional coating materials. Full article

(This article belongs to the Special Issue Food Colloids: 3rd Edition)

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19 pages, 5011 KiB

Open AccessArticle

One-Step Synthesis AlCo₂O₄ and Derived “Al” to Double Optimise the Thermal Decomposition Kinetics and Enthalpy of Ammonium Perchlorate

by Kaihua He, Yanzhi Yang, Zhengyi Zhao, Zhiyong Yan and Xuechun Xiao

Colloids Interfaces 2025, 9(3), 28; https://doi.org/10.3390/colloids9030028 - 10 May 2025

Abstract

The solution combustion method is widely used because of its simple operation and ability to produce porous structures. The chemical composition and morphological structure of the material can be regulated by different oxidiser-to-fuel ratios (φ). In this work, AlCo₂O₄ derived [...] Read more.

The solution combustion method is widely used because of its simple operation and ability to produce porous structures. The chemical composition and morphological structure of the material can be regulated by different oxidiser-to-fuel ratios (φ). In this work, AlCo₂O₄ derived “Al” catalytic materials were successfully synthesised by adjusting the fuel-to-oxidiser ratio using a one-step solution combustion method. On the one hand, the aluminium nanoparticles act as a part of the metal fuel in the composite solid propellant and, at the same time, serve as a catalytic material. In contrast, the thermal decomposition performance of AP was significantly improved by the synergistic catalysis of AlCo₂O₄. Among the samples prepared under different fuel ratios, considering all aspects (high-temperature decomposition temperature, activation energy, and decomposition heat) comprehensively, the AlCo₂O₄ prepared with φ = 0.5 had a more excellent catalytic effect on AP thermal decomposition, and the T_HTD of AP was reduced to 285.4 °C, which is 188.08 °C lower. The activation energy of the thermal decomposition of AP was also significantly reduced (from 296.14 kJ/mol to 211.67 kJ/mol). In addition, the ignition delay time of AlCo₂O₄-AP/HTPB was drastically shortened to 9 ms from 28 ms after the addition of 7% AlCo₂O₄ derived “Al” catalytic materials. Composite solid propellants have shown great potential for application. Full article

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13 pages, 3492 KiB

Open AccessFeature PaperArticle

Magnetic Field Control of Liquid Crystal-Enabled Colloid Electrophoresis

by Joel Torres-Andrés, Guillermo Cassinello, Francesc Sagués and Jordi Ignés-Mullol

Colloids Interfaces 2025, 9(3), 27; https://doi.org/10.3390/colloids9030027 - 6 May 2025

Abstract

Microswimmers are key for unveiling new physical phenomena underlying their propulsion, especially when driven inside complex fluids. Liquid crystals are anisotropic complex fluids that feature long-range orientational order. The propulsion of non-charged dielectric particles can be accomplished in these systems by breaking the [...] Read more.

Microswimmers are key for unveiling new physical phenomena underlying their propulsion, especially when driven inside complex fluids. Liquid crystals are anisotropic complex fluids that feature long-range orientational order. The propulsion of non-charged dielectric particles can be accomplished in these systems by breaking the particles’ fore-aft symmetry thanks to anisotropies in the conductivity and dielectric permittivity parameters of the liquid crystal. Under the application of an AC electric field, asymmetric osmotic flows are generated to propel non-spherical particles, whose direction of motion depends on the orientational order of the liquid crystal molecules around the inclusions. This means that, by controlling the LC orientation, one will be able to steer driven colloidal inclusions. In this experimental work, we show that a homogeneous magnetic field that is able to control the orientation of the liquid crystal molecules also allows us to determine the direction of motion of driven particles without significant changes in the propulsion mechanism. Additionally, we show that a radial configuration of the magnetic field lines can be used to generate topological defects in the liquid crystal orientational field that attract colloidal particles, leading to their clustering as rotating mills. The generated clusters were tested to study the collective motion of particles, suggesting the presence of particle–particle interactions. Full article

(This article belongs to the Special Issue State of the Art of Colloid and Interface Science in the Iberian Peninsula)

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16 pages, 2872 KiB

Open AccessArticle

Formulating Graphite-Filled PU Dispersions with Extended Shelf Life Using the Capillary Suspension Concept

by Katrin Dyhr and Norbert Willenbacher

Colloids Interfaces 2025, 9(3), 26; https://doi.org/10.3390/colloids9030026 - 2 May 2025

Abstract

Stabilizing micron-sized particles in low-viscosity polymer dispersions is challenging when density differences are present. This study demonstrates that graphite particles in aqueous polyurethane dispersions can be efficiently prevented from sedimentation using the capillary suspension concept. Capillary suspensions are solid/liquid/liquid systems and the capillary [...] Read more.

Stabilizing micron-sized particles in low-viscosity polymer dispersions is challenging when density differences are present. This study demonstrates that graphite particles in aqueous polyurethane dispersions can be efficiently prevented from sedimentation using the capillary suspension concept. Capillary suspensions are solid/liquid/liquid systems and the capillary forces inferred from adding a second immiscible fluid can lead to drastic changes in texture and flow. Here, both spherical and flake-shaped graphite particles were used as fillers, with octanol as the secondary liquid. At low graphite concentrations, octanol increases the low-shear viscosity significantly attributed to the formation of loose particle aggregates immobilizing part of the continuous phase. Above a critical graphite concentration, capillary forces induce a self-assembling, percolating particle network, leading to a sharp yield stress increase (>100 Pa). The corresponding percolating particle network efficiently suppresses sedimentation; for the system including 28 vol% spherical particles, a shelf life of at least six months was achieved. Capillary forces do not affect the high-shear viscosity of suspensions; here, a hydrophobically modified polyether thickener can be used. Transfer of the stabilization concept presented here to other high-density particles like silver or metal oxides suspended in other polymer dispersions is straightforward and is applicable in various fields like flexible printed electronics. Full article

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17 pages, 4755 KiB

Open AccessArticle

Influence and Correction of Refraction Phenomenon in Liquid Contact Angle Measurement in Capillary Tube

by Weixiu Shi, Mengmeng Ran and Lisheng Pan

Colloids Interfaces 2025, 9(3), 25; https://doi.org/10.3390/colloids9030025 - 23 Apr 2025

Abstract

By using clear vapor–liquid interface line images of the liquid inside the capillary, the measurement coordinate points of the vapor–liquid interface line were measured. A new method for measuring liquid contact angle has been proposed, which was used to calculate the actual coordinate [...] Read more.

By using clear vapor–liquid interface line images of the liquid inside the capillary, the measurement coordinate points of the vapor–liquid interface line were measured. A new method for measuring liquid contact angle has been proposed, which was used to calculate the actual coordinate points and fit the actual vapor–liquid interface line of the liquid. Finally, an angle measurement tool is used to measure the angle of the actual vapor–liquid interface line and obtain the actual contact angle of the liquid. Effectively reducing the influence of refraction on the contact angle by correcting the errors caused by the refractive index of different materials, it can be used for the precise measurement of the static contact angle of liquids. By measuring the static contact angle of the upper and lower liquid surfaces of the liquid column, it was found that the presence of refraction caused a difference of [1.84°, 5.61°] between the actual and measured values of the static contact angle. Full article

(This article belongs to the Special Issue Bubble and Drop 2025 (B&D 2025))

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15 pages, 2841 KiB

Open AccessFeature PaperArticle

A Bio-Based Collector Derived from Vitamin E for Hematite Flotation

by Rocky Mensah, Tammitage Danesh S. Perera, Tina Hsia, Pouria Amani, San H. Thang and Mahshid Firouzi

Colloids Interfaces 2025, 9(2), 24; https://doi.org/10.3390/colloids9020024 - 11 Apr 2025

Abstract

The increasing demand for sustainable mining practices has driven the development of environmentally friendly reagents for mineral processing. This study investigates vitamin E sodium succinate (VE_SS), a novel bio-based collector, for its potential in hematite flotation. The performance of VE_SS was benchmarked against [...] Read more.

The increasing demand for sustainable mining practices has driven the development of environmentally friendly reagents for mineral processing. This study investigates vitamin E sodium succinate (VE_SS), a novel bio-based collector, for its potential in hematite flotation. The performance of VE_SS was benchmarked against sodium oleate (NaOL), a widely used conventional collector in mineral processing. To assess the flotation performance of VE_SS, micro-flotation experiments were conducted using hematite, sourced from a mine, and silica, a common associated gangue mineral. These tests were complemented by comprehensive surface characterizations, including contact angle measurements, zeta potential analysis, Fourier-transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS), to investigate the adsorption mechanisms of VE_SS in comparison to NaOL. The results demonstrate that VE_SS effectively enhances hematite recovery, achieving levels comparable to NaOL. Furthermore, VE_SS exhibited reduced sensitivity to pH, addressing a key limitation of NaOL, which performs well in neutral to alkaline conditions but shows significantly lower recovery under acidic pH. These findings highlight the potential of VE_SS as a bio-based alternative to conventional collectors, contributing to the advancement of more sustainable mineral processing practices. Full article

(This article belongs to the Special Issue Colloids and Interfaces in Mineral Processing)

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