Unravelling the Interactions between Surface-Active Ionic Liquids and Triblock Copolymers for the Design of Thermal Responsive Systems
authors Perez-Sanchez, G; Vicente, FA; Schaeffer, N; Cardoso, IS; Ventura, SPM; Jorge, M; Coutinho, JAP
nationality International
journal JOURNAL OF PHYSICAL CHEMISTRY B
keywords CRITICAL MICELLIZATION TEMPERATURE; AGGREGATION BEHAVIOR; BLOCK-COPOLYMER; NONIONIC SURFACTANTS; MICELLE FORMATION; PHASE-BEHAVIOR; AQUEOUS-SOLUTIONS; SELF-AGGREGATION; CO-SURFACTANTS; DYNAMICS
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 [C(10)mim]Cl and [C-14 mim]Cl and phosphonium-based [P-4,P-4,P-4,P-14]CI 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 thereto-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.
publisher AMER CHEMICAL SOC
issn 1520-6106
isbn 1520-5207
year published 2020
volume 124
issue 32
beginning page 7046
ending page 7058
digital object identifier (doi) 10.1021/acs.jpcb.0c02992
web of science category Chemistry, Physical
subject category Chemistry
unique article identifier WOS:000562943100011
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  impact metrics
journal analysis (jcr 2019):
journal impact factor 2.857
5 year journal impact factor 2.88
category normalized journal impact factor percentile 50.629
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