Molecular insights into the pH-induced self-assembly of CTAB/PPA system

Liu, Zhibin; Wang, Pan; Pei, Supeng; Liu, Bing; Sun, Xiaoli; Zhang, Jun

doi:10.1016/j.colsurfa.2016.06.049

Cited by 25 publications

(8 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Porosity of the mSiO 2 shell surface can be observed from the Figure b, confirming a successful growth of mesoporous silica shell using a surfactant‐templating approach . Nevertheless, small agglomerates still formed after the mesoporous silica layer coating due to the oligomeration of siloxanes during the first coat and the low steric repulsion generated by the small length chain of the CTAB molecule, which avoid the good dispersion of these nanoparticles …”

Section: Resultsmentioning

confidence: 53%

Modification of Cotton Fibers with Magnetite and Magnetic Core‐Shell Mesoporous Silica Nanoparticles

Patiño-Ruiz

Sánchez-Botero

Hinestroza

et al. 2018

Physica Status Solidi (a)

View full text Add to dashboard Cite

Magnetite (Fe3O4) and magnetic core‐shell mesoporous silica (Fe3O4‐mSiO2) nanoparticles are employed to coat cotton fibers using a room temperature water‐based direct electrostatic assembly method with polyelectrolytes. Core‐shell nanoparticles are fabricated by coating super‐paramagnetic magnetite clusters with a mesoporous silica layer (mSiO2) using a surfactant‐templating approach. The Fe3O4 clusters are initially synthesized by a co‐precipitation process. The cotton fibers are modified through a layer‐by‐layer technique using dipping cycles with PDDA and PSS polyelectrolytes solutions to enable further nanoparticles attachment. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images provides morphologic information of the synthesized nanoparticles and the modified cotton fibers. Composition and physicochemical properties are studied by powder XRD, FTIR, and SEM‐EDX methods, and thermogravimetric analysis (TGA) are carried out to determine the amount of nanoparticles adsorbed onto cotton samples. The saturation magnetization (MS) of nanoparticles determined by a vibrating sample magnetometer (VSM) is greater than that of the cotton‐nanoparticles nano‐composites. Potential applications of these composite materials can include protective clothing and transdermal drug delivery systems.

show abstract

Section: Resultsmentioning

confidence: 53%

Modification of Cotton Fibers with Magnetite and Magnetic Core‐Shell Mesoporous Silica Nanoparticles

Patiño-Ruiz

Sánchez-Botero

Hinestroza

et al. 2018

Physica Status Solidi (a)

View full text Add to dashboard Cite

show abstract

“…To achieve this goal, molecular dynamics (MD) simulations are necessary to study the emulsification/demulsification processes incurred by the gas switchable surfactants. Over the past few decades, MD methods have been widely used to study the stimuli-responsive micellar structural transitions , and demulsification process with chemical demulsifiers. , However, to the best of our knowledge, MD simulations of the emulsification/demulsification using gas switchable surfactants are relatively scarce. Recently, we investigated the reversible solubilization behavior of pyrene with a CO 2 /N 2 -triggered surfactant ( N ′-dodecyl- N , N -dimethylacetamidinium bicarbonate, DDAB) .…”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulation of Emulsification/Demulsification with a Gas Switchable Surfactant

Liu

Tian

et al. 2019

J. Phys. Chem. C

View full text Add to dashboard Cite

Molecular dynamics simulations were performed to study the reversible emulsification and demulsification processes of a hexadecane/water mixture by a CO2/N2-triggered surfactant named N′-dodecyl-N,N-dimethylacetamidinium bicarbonate (DDAB). Specifically, the simulations reproduced experimental observations, that is, the active form of the surfactant, DDA+, which can stabilize hexadecane/water emulsions in aqueous solution. Furthermore, when DDA+ surfactants were switched to DDA molecules, their inactive form, the surfactant-stabilized emulsion was spontaneously broken, and the oil phase was separated from bulk water. The potential of mean force (PMF) between emulsion and oil droplets showed that the repulsion effect among the DDA+ headgroups played an essential role in stabilizing emulsion. Besides, radial and spatial distribution functions were applied to investigate the hydration behavior of DDA and DDA+. The results demonstrated that the DDA+ headgroups could be fully hydrated with water molecules located around the three methyl groups in the headgroup. Once the headgroup was deprotonated, the headgroup changed into a nonplanar conjugation structure. Moreover, the hydrophilicity of DDA headgroups decreased significantly compared with DDA+. The reversible transformation of the hydrophilicity is the key for switchable surfactants that can be used as an emulsifier and a demulsifier simultaneously. The hydrophilicity of the surfactants was quantified by PMF between surfactants and water, which could be used to compare the hydrophilic difference between the inactive and active forms of the molecule and is expected to help design new switchable surfactants.

show abstract

“…Recently, Morrow et al 21 used a continuous constant pH molecular dynamics method to study the self-assembly of lauric acids at different pH conditions, which showed a pH-dependent morphology of the aggregates. Liu et al 22 performed coarse-grained MD simulations to study the pH-dependent morphologies of CTAB and potassium phthalic acid (PPA) mixtures. The authors concluded that the electrostatic screening of the inserted PPA molecules played an important role in the pHinduced self-assembly.…”

Section: ■ Introductionmentioning

confidence: 99%

Molecular Dynamics Simulation of the pH-Induced Structural Transitions in CTAB/NaSal Solution

Yan¹,

Han

Li³

et al. 2017

Langmuir

View full text Add to dashboard Cite

We performed molecular dynamics simulations to study the pH-induced structural transitions for aqueous mixtures of a cationic surfactant (cetyltrimethylammonium bromide, CTAB) and a hydrotrope (sodium salicylate, NaSal). We obtained rigid cylindrical, spherical, and flexible cylindrical micelles at pH 7, 2, and 0, respectively, which agrees well with the experimental results of Umeasiegbu et al. (Langmuir 2016, 32, 655). By analyzing the different micellar structural properties, including distribution and molecular orientation of CTA and Sal inside the micelle, we found that the binding form of the protonated salicylate molecules with CTA is different from that of Sal ions. Because of the protonation of salicylate molecules with reduction in pH, their hydrogen bonding interactions with water molecules strengthened and the electrostatic interactions with CTA headgroups weakened. Thus, the repulsion of the CTA headgroups led to the breakage of the cylindrical micelle into spherical ones. At pH 0, the H-bond-strengthened cation-π interactions between salicylate and CTA were verified. We concluded that the penetration of salicylate molecules inside the micelle and the strong association of Cl ions on the micellar surface play a key role in the formation of a flexible cylindrical micelle. This work provides an atomic-level insight into the mechanism of pH-induced shape transitions in the CTAB/NaSal systems, which is expected to be helpful to understand the aggregate behavior of cationic surfactant-hydrotrope solution.

show abstract

Molecular insights into the pH-induced self-assembly of CTAB/PPA system

Cited by 25 publications

References 37 publications

Modification of Cotton Fibers with Magnetite and Magnetic Core‐Shell Mesoporous Silica Nanoparticles

Modification of Cotton Fibers with Magnetite and Magnetic Core‐Shell Mesoporous Silica Nanoparticles

Molecular Dynamics Simulation of Emulsification/Demulsification with a Gas Switchable Surfactant

Molecular Dynamics Simulation of the pH-Induced Structural Transitions in CTAB/NaSal Solution

Contact Info

Product

Resources

About