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1. Dodecagonal quasicrystals of oil-swollen ionic surfactant micelles

   https://doi.org/10.1073/pnas.2101598118  

   Jayaraman, Ashish; Baez-Cotto, Carlos M.; Mann, Tyler J.; Mahanthappa, Mahesh K. (July 2021, Proceedings of the National Academy of Sciences)

   null (Ed.)

   A delicate balance of noncovalent interactions directs the hierarchical self-assembly of molecular amphiphiles into spherical micelles that pack into three-dimensional periodic arrays, which mimic intermetallic crystals. Herein, we report the discovery that adding water to a mixture of an ionic surfactant and n -decane induces aperiodic ordering of oil-swollen spherical micelles into previously unrecognized, aqueous lyotropic dodecagonal quasicrystals (DDQCs), which exhibit local 12-fold rotational symmetry and no long-range translational order. The emergence of these DDQCs at the nexus of dynamically arrested micellar glasses and a periodic Frank–Kasper (FK) σ phase approximant sensitively depends on the mixing order of molecular constituents in the assembly process and on sample thermal history. Addition of n -decane to mixtures of surfactant and water instead leads only to periodic FK A15 and σ approximants with no evidence for aperiodic order, while extended ambient temperature annealing of the DDQC also reveals its transformation into a σ phase. Thus, these lyotropic DDQCs are long-lived metastable morphologies, which nucleate and grow from a stochastic distribution of micelle sizes formed by abrupt segregation of varied amounts of oil into surfactant micelles on hydration. These findings indicate that molecular building block complexity is not a prerequisite for the formation of aperiodic supramolecular order, while also establishing the generic nature of quasicrystalline states across metal alloys and self-assembled micellar materials. 

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2. An Investigation of the Effect of pH on Micelle Formation by a Glutamic Acid-Based Biosurfactant

   https://doi.org/10.3390/colloids8030038  

   Mayer, Jacob D; Rauscher, Robert M; Fritz, Shayden R; Fang, Yayin; Billiot, Eugene J; Billiot, Fereshteh H; Morris, Kevin F (June 2024, Colloids and Interfaces)

   NMR spectroscopy, molecular modeling, and conductivity experiments were used to investigate micelle formation by the amino acid-based surfactant tridecanoic L-glutamic acid. Amino acid-based biosurfactants are green alternatives to surfactants derived from petroleum. NMR titrations were used to measure the monomeric surfactant’s primary and gamma (γ) carboxylic acid pKa values. Intramolecular hydrogen bonding within the surfactant’s headgroup caused the primary carboxylic acid to be less acidic than the corresponding functional group in free L-glutamic acid. Likewise, intermolecular hydrogen bonding caused the micellar surfactant’s γ carboxylic functional group to be less acidic than the corresponding monomer value. The binding of four positive counterions to the anionic micelles was also investigated. At pH levels below 7.0 when the surfactant headgroup charge was −1, the micelle hydrodynamic radii were larger (~30 Å) and the mole fraction of micelle-bound counterions was in the 0.4–0.7 range. In the pH range of 7.0–10.5, the micelle radii decreased with increasing pH and the mole fraction of micelle bound counterions increased. These observations were attributed to changes in the surfactant headgroup charge with pH. Above pH 10.5, the counterions deprotonated and the mole fraction of micelle-bound counterions decreased further. Finally, critical micelle concentration measurements showed that the micelles formed at lower concentrations at pH 6 when the headgroup charge was predominately −1 and at higher concentrations at pH 7 where headgroups had a mixture of −1 and −2 charges in solution. 

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3. Synthesis of shape‐controlled silica nanoparticles via dual soft templates: A comparative study between aqueous and microemulsion synthesis for the impregnation of procaine anaesthesia drug

   https://doi.org/10.1002/cjce.70087  

   Daikh, Zine eddine; Zeitoun, Edrees Abu; Fergoug, Teffaha; Bouhadda, Youcef; Derkaoui, Khaled; Bekki, Khaled; Kadiri, Aicha; Chaker, Yassine; El_Nokab, Mustapha_El Hariri; Vojvodin, Cameron S; et al (September 2025, The Canadian Journal of Chemical Engineering)

   Abstract Silica nanoparticles (SiNPs) are promising drug delivery nanocarriers due to their tunable size, porous structure, and surface properties. This study compares two synthesis methods: (i) a low‐temperature aqueous sol–gel process yielding SiNPs of 500–700 nm, and (ii) a water‐in‐oil (W/O) microemulsion using either CTAB or TX‐100 surfactants. Surfactant selection significantly affected nanoparticle size, stability, and dispersity. Characterization by dynamic light scattering (DLS), scanning electron microscopy (SEM), X‐ray diffraction (XRD), Brunauer–Emmett–Teller (BET), solid‐state nuclear magnetic resonance spectroscopy (ssNMR), X‐ray photoelectron spectroscopy (XPS), and photoluminescence analysis (PL) confirmed successful synthesis. The TX‐100‐mediated microemulsion method proved particularly effective in achieving highly stable, reproducible, and monodisperse SiNPs, with a size limit of approximately 100 nm, making them ideal candidates for drug encapsulation. Procaine (PRC) incorporation demonstrated the role of reverse micelle dynamics and surfactant‐stabilized interfaces in enhancing encapsulation efficiency. This work highlights the critical role of surfactant and medium selection in SiNPs synthesis, demonstrating their impact on nanoparticle stability, dispersity, and drug loading efficiency. The TX‐100‐mediated microemulsion technique emerges as a superior approach for producing stable, monodisperse SiNPs, advancing the design of nanocarriers for PRC drug delivery applications. 

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4. Engineering a Surfactant Trap via Postassembly Modification of an Imine Cage

   https://doi.org/10.1021/acs.chemmater.4c01808  

   Pérez-Ferreiro, María; Gallagher, Quinn M; León, Andrea B; Webb, Michael A; Criado, Alejandro; Mosquera, Jesús (September 2024, Chemistry of Materials)

   Imine self-assembly stands as a potent strategy for the preparation of molecular organic cages. However, challenges persist, such as water insolubility and limited recognition properties due to constraints in the application of specific components during the self-assembly process. In this study, we addressed these limitations by initially employing a locking strategy, followed by a postassembly modification. This sequential approach enables precise control over both the solubility and host–guest properties of an imine-based cage. The resulting structure demonstrates water solubility and exhibits an exceptional capacity to selectively interact with anionic surfactants, inducing their precipitation. Remarkably, each cage precipitates 24 equiv of anionic surfactants even at concentrations much lower than the surfactant’s critical micelle concentration (CMC), ensuring their complete removal. Molecular simulations elucidate how anionic surfactants specifically interact with the cage to facilitate aggregation below the surfactant CMC and induce precipitation as a micellar cross-linker. This innovative class of cages paves the way for the advancement of materials tailored for environmental remediation. 

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5. Hybrid Huff-n-Puff Process for Enhanced Oil Recovery: Integration of Surfactant Flooding with CO2 Oil Swelling

   https://doi.org/10.3390/app142412078  

   Ratanpara, Abhishek; Donjuan, Joshua; Smith, Camron; Procak, Marcellin; Aboubakar, Ibrahima; Mandin, Philippe; Al-Raoush, Riyadh I; Inguanta, Rosalinda; Kim, Myeongsub (December 2024, Applied Sciences)

   With increasing energy demands and depleting oil accessibility in reservoirs, the investigation of more effective enhanced oil recovery (EOR) methods for deep and tight reservoirs is imminent. This study investigates a novel hybrid EOR method, a synergistic approach of nonionic surfactant flooding with intermediate CO2-based oil swelling. This study is focused on the efficiency of surfactant flooding and low-pressure oil swelling in oil recovery. We conducted a fluorescence-based microscopic analysis in a microchannel to explore the effect of sodium dodecyl sulfate (SDS) surfactant on CO2 diffusion in Texas crude oil. Based on the change in emission intensity of oil, the results revealed that SDS enhanced CO2 diffusion at low pressure in oil, primarily due to SDS aggregation and reduced interfacial tension at the CO2 gas–oil interface. To validate the feasibility of our proposed EOR method, we adopted a ‘reservoir-on-a-chip’ approach, incorporating flooding tests in a polymethylmethacrylate (PMMA)-based micromodel. We estimated the cumulative oil recovery by comparing the results of two-stage surfactant flooding with intermediate CO2 swelling at different pressures. This novel hybrid approach test consisted of a three-stage sequence: an initial flooding stage, followed by intermediate CO2 swelling, and a second flooding stage. The results revealed an increase in cumulative oil recovery by nearly 10% upon a 2% (w/v) solution of SDS and water flooding compared to just water flooding. The results showed the visual phenomenon of oil imbibition during the surfactant flooding process. This innovative approach holds immense potential for future EOR processes, characterized by its unique combination of surfactant flooding and CO2 swelling, yielding higher oil recovery. 

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