Spontaneous vesicle formation from trisiloxane-tailed gemini surfactant

Research Progress in Structure Synthesis, Properties, and Applications of Small-Molecule Silicone Surfactants

Silicone surfactants have garnered significant research attention owing to their superior properties, such as wettability, ductility, and permeability. Small-molecular silicone surfactants with simple molecular structures outperform polymeric silicone surfactants in terms of surface activity, emulsification, wetting, foaming, and other areas. Moreover, silicone surfactants with small molecules exhibit a diverse and rich molecular structure. This review discusses various synthetic routes for the synthesis of different classes of surfactants, including single-chain, "umbrella" structure, double chain, bolaform, Gemini, and stimulus-responsive surfactants. The fundamental surface/interface properties of the synthesized surfactants are also highlighted. Additionally, these surfactants have demonstrated enormous potential in agricultural synergism, drug delivery, mineral flotation, enhanced oil recovery, separation, and extraction, and foam fire-fighting.

Synthesis and Micellization of Carbosilane Sulfonate Surfactants with Short Alkyl Chains

Carbosilane surfactants, consisting of carbosilane as a hydrophobic group linked to hydrophilic groups, are one kind of silicone surfactants. In this paper, a series of carbosilane sulfonate surfactants with short alkyl chains (Cn-Si2C-SO3Na (n = 1-6)), Me-Si2C-SO3Na, Et-Si2C-SO3Na, Pr-Si2C-SO3Na, Bu-Si2C-SO3Na, Pen-Si2C-SO3Na, and Hex-Si2C-SO3Na, were prepared and characterized by 29 Si NMR, 1H NMR, and FT-IR spectroscopies. The influence of the alkyl chain length on their micellization was studied using surface tension, dynamic light scattering, conductivity, and transmission electron microscopy. The CMC value decreases with increasing length of the short alkyl group. The γCMC value of Cn-Si2C-SO3Na (n = 1-6) increases as the alkyl chain increases from methyl to propyl, while the γCMC value gradually decreases as the alkyl chain increases from propyl to hexyl. The larger and rigid tetramethyldicarbosilane group functioned synergistically with a short alkyl chain, resulting in carbosilane sulfonate surfactants adsorbing at the air/water interface with a rugby ball shape; accordingly, the Amin values of the investigated carbosilane sulfonate surfactants increase with increasing length of the alkyl chain. The micellization process of carbosilane sulfonate surfactants is enthalpy-driven at lower temperatures and entropy-driven at high temperatures. The ΔHm0 values became more negative and ΔSm0 values more positive as the alkyl chain length increased. Aggregates in the range of 10-800 nm were observed for Cn-Si2C-SO3Na (n = 1-6) in an aqueous solution, and the hydrodynamic diameter (Dh) decreased with increasing length of the short alkyl group.

Vitamin D3 Loaded Niosomes and Transfersomes Produced by Ethanol Injection Method: Identification of the Critical Preparation Step for Size Control

Vesicular nanocarriers have an important role in drug delivery and dietary supplements. Size control and optimization of encapsulation efficiency (EE) should be optimized for those applications. In this work, we report on the identification of the crucial step (injection, evaporation, or sonication) innanovesicles (transfersomes and niosomes) preparation by theethanol injection method (EI). The identification of each production step on the final vesicle size was analyzed in order to optimize further scale-up process. Results indicated that the final size of transfersomeswas clearly influenced by the sonication step while the final size of niosomes was mainly governed by the injection step. Measurements of final surface tension of the different vesicular systems prepared indicate a linear positive tendency with the vesicle size formed. This relation could help to better understand the process and design a vesicular size prediction model for EI. Vitamin D3 (VitD3) was encapsulated in the systems formulated with encapsulation efficiencies larger than 90%. Interaction between the encapsulated compound and the membrane layer components is crucial for vesicle stability. This work has an impact on the scaling-up production of vesicles for further food science applications.

Review on Silicone Surfactants: Silicone-based Gemini Surfactants, Physicochemical Properties and Applications

The increasing use of silicone polymers has attracted the interest of many researchers and manufacturers for the past three decades. The silicone surfactants have excellent surface properties, of which the wetting and spreading ability is particularly noteworthy. So silicone surfactants are used in various fields, starting with textiles to agriculture. Because of this particular wetting and spreading property, silicone surfactants will be used together with conventional surfactants to achieve the desired throughput. In this paper we describe in detail the origin of silicone surfactants and various silicone surfactant compounds, as well as their physicochemical properties. We also handle various applications of silicone surfactants in agriculture, textile manufacturing, personal care and cosmetics, polyurethane foam, metal extraction, foam floatation and other industrial applications. However, the main focus is on the latest syntheses, developments and applications of newly developed tailor-made molecules.

Aggregation Behavior of "Linear" Trisiloxane Surfactant with Different Terminal Groups (CH3-, ClCH2-, and CF3-) in Aqueous Solution

Novel "linear" trisiloxane surfactants with different terminal groups (CH₃-, ClCH₂-, CF₃-) and two polyether hydrophilic groups were successfully synthesized and confirmed using ¹H NMR, ¹³C NMR, ²⁹Si NMR, and FT-IR spectroscopy. The aggregation and adsorption behavior of the "linear" trisiloxane surfactants in aqueous solution was studied by surface tension, dynamic light scattering (DLS), transmission electron microscopy (FF-TEM), and TEM. Owing to the introduction of two polyether hydrophilic groups in the terminal positions of the trisiloxane hydrophobic part, "linear" trisiloxane surfactants (Me-Si₃-EO₈, Cl-Si₃-EO₈, and F-Si₃-EO₈) tend to lie flat in the air/water interface and result in an increasing the surface tension at the CMC ( γ_CMC) and single trisiloxane surfactant molecule at the air/water interface ( A _min) values. Following the difference in the intermolecular forces and molecular volumes (CH₃- < ClCH₂- < CF₃-), the γ_CMC values decrease following the order Me-Si₃-EO₈ > Cl-Si₃-EO₈ > F-Si₃-EO₈, and the adsorption efficiency ( p C₂₀), surface pressure at the CMC ( π_CMC), CMC/ C₂₀ , and A _min values increase following the order Me-Si₃-EO₈ < Cl-Si₃-EO₈ < F-Si₃-EO₈. As comparison, fluorinated trisiloxane surfactant (F-Si₃-EO₈) has greater surface activity attributed to the terminal CF₃- group. The TEM and FF-TEM results illustrated that all the investigated "linear" trisiloxane surfactants can form nonuniform size spherical aggregates.

Transition from Micelle to Vesicle of a Novel Sugar-Based Surfactant Containing Trisiloxane

Vesicles form spontaneously in aqueous solution of a novel sugar-based surfactant containing trisiloxane [Si(3)N-GHA]. The transition was monitored among the monomer, micelle and vesicle through the variation of surface tension, accompanied by surface tension measurements. The vesicles of a trisiloxane containing sugar-based surfactant have been characterized by dynamic light scattering (DLS) and negative-stained transmission electron microscopy (TEM). The vesicle aggregation can be explained by the critical packing parameter derived from an analysis of chemical structure.