Colloids and Interfaces

10 pages, 1377 KiB

Open AccessCommunication

An Adoption of the Fractional Maxwell Model for Characterizing the Interfacial Dilational Viscoelasticity of Complex Surfactant Systems

by Giuseppe Loglio, Agnieszka Czakaj, Ewelina Jarek, Volodymyr I. Kovalchuk, Marcel Krzan, Libero Liggieri, Reinhard Miller and Piotr Warszynski

Colloids Interfaces 2024, 8(4), 44; https://doi.org/10.3390/colloids8040044 - 30 Jul 2024

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Abstract

In this communication, the single-element version of the fractional Maxwell model (single FMM) is adopted to quantify the observed behaviour of the interfacial dilational viscoelasticity. This mathematical tool is applied to the results obtained by the oscillating drop method for aqueous solutions of ethyl lauroyl arginate (LAE). The single FMM adequately fits the experimental results, fairly well characterizing the frequency dependence of the modulus and the inherent phase-shift angle of the complex physical quantity, i.e., the interfacial dilational viscoelasticity. Further speculations are envisaged to apply the FMM to step perturbations in the time domain, allowing for the same parameter set as in the frequency domain. Full article

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10 pages, 5528 KiB

Open AccessArticle

Heat Transfer Fluids Based on Amino-Functionalized Silica Dispersed in 1,2-Propylene Glycol and in 50-50 Aqueous 1,2-Propylene Glycol

by Marta Kalbarczyk, Sebastian Skupiński and Marek Kosmulski

Colloids Interfaces 2024, 8(4), 43; https://doi.org/10.3390/colloids8040043 - 16 Jul 2024

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Abstract

1,2-propylene glycol and its 50-50 w/w mixture with water were used to prepare heat transfer fluids based on amino-functionalized silica. On top of pH-neutral dispersions (no reagents added except for the solvent and the particles), dispersions acidified with acetic acid and with HCl were used to enhance the positive electric charge of silica particles. The colloidal particles had a positive zeta potential >40 mV and showed apparent particle radii of 70 nm, and these properties remained unchanged on heating up to 80 °C for up to 28 days. Full article

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12 pages, 2527 KiB

Open AccessArticle

Co-Encapsulation of Paclitaxel and Doxorubicin in Liposomes Layer by Layer

by Isaac Izcoatl Mota Díaz, Janna Douda, Patricia García López, Sandra Edith Cabrera Becerra, Miguel Ángel Gómez Álvarez, Rebeca Jiménez Rodríguez, Rafael Jurado León and Pedro López Sánchez

Colloids Interfaces 2024, 8(4), 42; https://doi.org/10.3390/colloids8040042 - 2 Jul 2024

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Abstract

The synergistic effect of antineoplastic drug co-encapsulation systems has made them highly regarded due to their improved pharmacological efficacy. Biopolymer-coated liposomes were evaluated for paclitaxel and doxorubicin co-encapsulation in MCF-7 and MDA-MB-231 breast cancer cell lines. These nanosystems are characterized by dynamic light scattering, transmission electron microscopy, and UV–VIS spectroscopy. The conventional and hybrid liposomal systems presented sizes of 150 to 230 nm and %EE greater than 80% for the encapsulated active ingredients. These drug-laden liposomal systems significantly decreased cell viability in both breast cancer cell lines compared with liposome-free drugs. The delivery of antineoplastic drugs in breast cancer therapy could potentially benefit from new hybrids for drug co-encapsulation. Full article

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13 pages, 10449 KiB

Open AccessArticle

Study of Interfacial Properties of Anionic–Nonionic Surfactants Based on Succinic Acid Derivatives via Molecular Dynamics Simulations and the IGMH Method

by Wannian Zhang, Feng Luo, Zhigang Gao, Haizhu Chi, Jinlong Wang, Fang Yu and Yu-Peng He

Colloids Interfaces 2024, 8(4), 41; https://doi.org/10.3390/colloids8040041 - 1 Jul 2024

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Abstract

Surfactants are widely used in fields such as oil recovery and flotation. The properties and mechanisms of surfactants can be effectively studied using molecular dynamics (MD) simulations. Herein, the aggregation behavior of surfactants was studied at the oil–water interface by MD simulation, and the micro-morphology of surfactants was analyzed under a low concentration and saturated state at the oil–water interface, respectively. The visualization results of the MD simulation showed that DTOA was saturated at the oil–water interface at 120 surfactant molecules, whereas 160 surfactant molecules were required for BEMA. In addition, the effect of surfactant concentration on the interfacial thickness and hydrogen bond distribution was studied, with the inflection point of hydrogen bond distribution identified as a characteristic parameter for surfactant saturation at the oil–water interface. The aggregation behavior of their hydrophobic and hydrophilic chains at the oil–water interface was qualitatively assessed using order parameters. Finally, the aggregation state of surfactants in salt-containing systems was studied, and it was found that the surfactants could effectively adsorb magnesium ions and calcium ions at the oil–water interface. However, the curve of the number of hydrogen bonds varies greatly, with a possible reason being that BEMA has a different coordination manner with diverse metal ions. This study provides some original insights into both the theoretical study and practical application of anionic and nonionic surfactants. Full article

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32 pages, 4249 KiB

Open AccessFeature PaperArticle

Predictive Approach to the Phase Behavior of Polymer–Water–Surfactant–Electrolyte Systems Using a Pseudosolvent Concept

by Ji-Zen Sheu and Ramanathan Nagarajan

Colloids Interfaces 2024, 8(4), 40; https://doi.org/10.3390/colloids8040040 - 21 Jun 2024

Viewed by 464

Abstract

A predictive approach to the phase behavior of four-component polymer–water–surfactant–electrolyte systems is formulated by viewing the four-component system as a binary polymer–pseudosolvent system, with the pseudosolvent representing water, surfactant, and the electrolyte. The phase stability of this binary system is examined using the framework of the lattice fluid model of Sanchez and Lacombe. In the lattice fluid model, a pure component is represented by three equation-of-state parameters: the hard-core volume of a lattice site (

v^{*}

), the number of lattice sites occupied by the component (r), and its characteristic energy (

ε^{*}

). We introduce the extra-thermodynamic postulate that r and

v^{*}

for the pseudosolvent are the same as for water and all surfactant–electrolyte composition-dependent characteristics of the pseudosolvent can be represented solely through its characteristic energy parameter. The key implication of the postulate is that the phase behavior of polymer–pseudosolvent systems will be identical for all pseudosolvents with equal values of characteristic energy, despite their varying real compositions. Based on the pseudosolvent model, illustrative phase diagrams have been computed for several four-component systems containing alkyl sulfonate/sulfate surfactants, electrolytes, and anionic or nonionic polymers. The pseudosolvent model is shown to describe all important trends in experimentally observed phase behavior pertaining to polymer and surfactant molecular characteristics. Most importantly, the pseudosolvent model allows one to construct a priori phase diagrams for any polymer–surfactant–electrolyte system, knowing just one experimental composition data for a system at the phase boundary, using available thermodynamic data on surfactants and electrolytes and without requiring any information on the polymer. Full article

(This article belongs to the Special Issue Surfactants and Interfaces)

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Colloids Interfaces, Volume 8, Issue 4 (August 2024) – 5 articles

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