Tuning Cationic Micelle Properties with an Antioxidant Additive: A Molecular Perspective

Abstract

In this work, we characterize the micellization and morphology transition induced in aqueous cetyltrimethylammonium bromide (CTAB) solution by the addition of the antioxidant propyl gallate (PG) using tensiometry, rheology, and small-angle neutron scattering (SANS) techniques combined with the molecular dynamics (MD) simulation approach. The adsorption of CTAB at the air–water interface in the presence of varying [PG] revealed a progressive decrease in the critical micelle concentration (CMC), while the changes in different interfacial parameters indicated enhancement of the hydrophobicity induced by PG in the CTAB micellar system. The dynamic rheology behavior indicated an increase in the flow viscosity (η) as a function of [PG]. Moreover, the rheological components (storage modulus, G′, and loss modulus, G″) depicted the viscoelastic features. SANS measurements depicted the existence of ellipsoidal micelles with varying sizes and aggregation number (N agg) as a function of [PG] and temperature. Computational simulation performed using density functional theory (DFT) calculations and molecular dynamics (MD) provided an insight into the atomic composition of the examined system. The molecular electrostatic potential (MEP) analysis depicted a close proximity of CTAB, i.e., emphasized favorable interactions between the quaternary nitrogen of CTAB and the hydroxyl group of the PG monomer, further validated by the two-dimensional nuclear Overhauser enhancement spectroscopy (2D-NOESY), which showed the penetration of PG inside the CTAB micelles. In addition, various dynamic properties, viz., the radial distribution function (RDF), the radius of gyration (R g), and solvent-accessible surface area (SASA), showed a significant microstructural evolution of the ellipsoidal micelles in the examined CTAB–PG system, where the changes in the micellar morphology with a more elongated hydrophobic chain and the increased R g and SASA values indicated the notable intercalation of PG in the CTAB micelles.

Adsorption Mechanism of Benzene Alkylation System Catalyzed by an Acid Catalyst: Effect of Pressure

“…RDFs can be used to identify the probability of the presence of other particles at a distance of r away from a given reference particle. RDFs can be used to map the adsorption sites and help determine the adsorption mechanism. ,, …”

“…RDFs can be used to map the adsorption sites and help determine the adsorption mechanism. 16,19,20 Figure 9a,b shows RDFs of the COM of the adsorbates in an equimolar BEN/PRO system (COM BEN and COM PRO ) around the center of the SCs (Center SC ), denoted as COM BEN -Center SC and COM PRO -Center SC , respectively. At loadings below C-P, the RDFs of BEN and PRO show a single main peak at r = 4.1 and 3.7 Å, which represents the adsorption of adsorbents on the optimal S-site.…”

Self-Assembly and Micellar Transition in CTAB Solutions Triggered by 1-Octanol

“…To decrease evaporative losses, a water-filled solvent trap was employed. 8 Small-Angle Neutron Scattering (SANS). The neutron scattering analysis was carried out using a diffractometer at the Dhruva reactor (Bhabha Atomic Research Centre, BARC), Trombay, India.…”

“…Such a trend agrees well with the reported literature. 6,8,35 Computational Study. The dependence on the orbital energy difference in the examined system is depicted in Figure 5.…”

“…Values are taken from our reported literature. 8 Here, a = semimajor axis, b = semiminor axis, R hs = hard sphere radius, ϕ = volume fraction, α = fractional charge, and N agg = aggregation number. molecules interacting with the system at 200 mM C 8 OH is higher than that in 100 mM C 8 OH.…”