Unravelling the Interactions between Surface-Active Ionic Liquids and Triblock Copolymers for the Design of Thermal Responsive Systems

Abstract

The tunable properties of surface-active ionic liquids (SAILs) and Pluronics are dramatically magnified by combining them in aqueous solutions. The thermo-controlled character of both, essential in the extraction of valuable compounds, can be fine-tuned by properly selecting the Pluronic and SAIL nature. However, further understanding of the nanoscale interactions directing the aggregation in these complex mixtures is needed to effectively design and control these systems. In this work, a simple and transferable coarse-grained model for molecular dynamics simulations, based on the MARTINI force field, is presented to study the impact of SAILs in Pluronics aggregation in aqueous solutions. The diverse amphiphilic characteristics and micelle morphologies were exemplified by selecting four archetypical nonionic Pluronicstwo normal, L-31 and L-35, and two reverse, 10R5 and 31R1. The impact of the alkyl chain length and the headgroup nature were evaluated with the imidazolium-based [C10mim]Cl and [C14mim]Cl and phosphonium-based [P4,4,4,14]Cl SAILs. Cloud point temperature (CPT) measurements at different Pluronic concentrations with 0.3 wt % of SAIL in aqueous solution emphasized the distinct impact of SAIL nature on the thermo-response behavior. The main effect of SAIL addition to nonionic Pluronics aqueous solutions is the formation of Pluronic/SAIL hybrid micelles, where the presence of SAIL molecules introduces a charged character to the micelle surface. Thus, additional energy is necessary to induce micelle aggregation, leading to the observed increase in the experimental CPT curves. The SAIL showed a relatively weak impact in Pluronic micelles with relatively high PPG hydrophobic content, whereas this effect was more evident when the Pluronic hydrophobic/hydrophilic strength is balanced. A detailed analysis of the Pluronic/SAIL micelle density profiles showed that the phosphonium head groups were positioned inside the micelle core, whereas smaller imidazolium head groups were placed much closer to the hydrophilic PEG corona, leading to a distinct effect on the cloud point temperature for those two classes of SAILs. Herein, the phosphonium-based SAIL induces a lower repulsion between neighboring micelles than the imidazolium-based SAILs, resulting in a less pronounced increase of the CPT. The model presented here offers, for the first time, an intuitive and powerful tool to unravel the complex thermo-response behavior of Pluronic and SAIL mixtures and support the design of tailor-made thermal controlled solvents.

Mechanistic Understanding from Molecular Dynamics in Pharmaceutical Research 2: Lipid Membrane in Drug Design

“…Antiseptic Picloxydine, Octenidine, Miramistin [470], Polyhexamethylene Biguanide [471] Insecticide Parathione [132], Fipronil [472], Dibutyl succinate [203] Former Drugs d-sotalol, cisapride [473], piracetam (status varies among countries) [474], ORG-12962 [199] Toxic xenobiotic Polybrominated-diphenyl-ethers [475], Bisphenol [476], Perfluoroalkyls [477], nitroaromatic explosives (TNT,2A, and 24DA) [478][479][480][481], 1,4-Dioxane [482], Benzo[a]pyrene [483] Nanomaterials Graphene [484][485][486][487], Carbon Dots [488], Phosphorene Oxide Nanosheets [489], Gold Nanoparticles [490][491][492], Titanium Dioxide Nanoparticles [493], Generic Nanoparticles (coarse grained) [494], Fullerene [495][496][497][498], Previous reviews [499] Polymers Poly(ethyleneoxide)-Poly-(propylene oxide) [500], polyethylenimine [501], Poloxamer [502,503], Pluronics [504,505], poly(ethyleneglycol)-desferrioxamine/ gallium [506], PEG functionalized with carbochydrates [507] and peptides…”

Using coarse-grained molecular dynamics to understand the effect of ionic liquids on the aggregation of Pluronic copolymer solutions

“…[24][25][26][27] The radial distribution functions and densities of atomistic models were here taken as a reference and used to find a suitable topology for the CG versions as previously reported for other ILs. 28,29 It must be highlighted that modelling relatively small molecules is difficult with MARTINI mainly due to the 4:1 CG mapping (4 heavy atoms per interaction bead). Once the CG models for the ILs were obtained, F-68 and L-35 aqueous solutions (taken as a references) and their mixtures with [Ch]Cl and [Ch][Hex] ILs were analysed by MD simulations and the obtained results compared with previous experimental data.…”

The Martini Model in Materials Science

“…With lipids being one special class of surfactants, early on Martini was extended to simulate the assembly and interaction of other synthetic ionic and nonionic surfactants. [ 35,83,113,278–283 ] Recently, interest in surfactants has renewed as ionic liquids (ILs) have attracted much attention for their use as biocompatible and green solvents and co‐solvents. This has led several authors to use Martini to simulate the self‐assembly of IL mesophases, [ 284,285 ] the process of IL‐mediated extractions, [ 285,286 ] as well as to guide the design of de novo molecules.…”