Ion-Conductive and Elastic Slide-Ring Gel Li Electrolytes Swollen with Ionic Liquid

Viscosity of Ionic Liquids: Theories and Models

Ionic liquids (ILs) offer a wide range of promising applications due to their unique and designable properties compared to conventional solvents. Further development and application of ILs require correlating/predicting their pressure-viscosity-temperature behavior. In this review, we firstly introduce methods for calculation of thermodynamic inputs of viscosity models. Next, we introduce theories, theoretical and semi-empirical models coupling various theories with EoSs or activity coefficient models, and empirical and phenomenological models for viscosity of pure ILs and IL-related mixtures. Our modelling description is followed immediately by model application and performance. Then, we propose simple predictive equations for viscosity of IL-related mixtures and systematically compare performances of the above-mentioned theories and models. In concluding remarks, we recommend robust predictive models for viscosity at atmospheric pressure as well as proper and consistent theories and models for P-η-T behavior. The work that still remains to be done to obtain the desired theories and models for viscosity of ILs and IL-related mixtures is also presented. The present review is structured from pure ILs to IL-related mixtures and aims to summarize and quantitatively discuss the recent advances in theoretical and empirical modelling of viscosity of ILs and IL-related mixtures.

Polymer network formation mechanism of multifunctional poly(ethylene glycol)s in ionic liquid electrolyte with a lithium salt

We report a controlled polymer network gel electrolyte based on a multifunctional poly(ethylene glycol) (PEG) prepolymer (herein, tetrafunctional PEGs (tetra-PEGs) and bisfunctional linear PEGs (linear-PEGs)) and an ionic liquid (IL)-based electrolyte solution containing lithium bis(trifluoromethanesulfonyl)imide (LiTFSA) salt. The gel electrolyte was obtained via a gelation reaction, i.e., the Michael addition reaction between maleimide (MA)-terminated tetra-PEGs and thiol (SH)-terminated tetra- or linear-PEGs (termed tetra/tetra-PEG gel or tetra/linear-PEG gel systems), in a LiTFSA/IL solution under noncatalytic conditions at room temperature. For the tetra/linear-PEG system, the gelation reaction depended on the ratio of tetra-PEG-MA and linear-PEG-SH; an optimum terminal MA/SH ratio of 1 : 1 yielded a reaction efficiency (p) of ∼98% (an ideal polymer network structure). The tetra/tetra-PEG system with an MA/SH ratio of 1 : 1 also achieved a reaction efficiency of ∼98%. Time-resolved rheological measurements revealed that the network formation process can be categorized into three steps: (I) oligomer formation at an early stage of the reaction, (II) formation of a roughly linked polymer network with a large mesh size as the reaction proceeded, and (III) full network formation also at the local scale near the gelation completion time. The resulting tetra/linear-PEG ion gel with an optimum MA/SH ratio of 1 : 1 exhibited high stretchability, enduring approximately 10-fold elongation, and superior ion-conducting properties compared with the corresponding IL-based electrolyte solution.

Post-synthesis modification of slide-ring gels for thermal and mechanical reconfiguration

Ring-sliding behavior in polyrotaxanes imbues gels, elastomers, and glasses with remarkable stress-dissipation and actuation properties. Since these properties can be modulated and tuned by structural parameters, many efforts have been devoted to developing synthetic protocols that define the structures and properties of slide-ring materials. We introduce post-synthetic modifications of slide-ring gels derived from unmodified α-cyclodextrin and poly(ethylene glycol) polyrotaxanes that enable (i) actuation and control of the thermo-responsive lower critical solution temperature (LCST) behavior of ring-modified slide-ring hydrogels, and (ii) chemically bonding separate gels into hybrid or shape-reconfigured macro-structures with a slide-ring adhesive solution. The mechanical properties of the post-modified gels have been characterized by shear rheology and uniaxial tensile tests, while the corresponding xerogels were characterized by wide-angle X-ray scattering. These demonstrations show that post-synthetic modification offers a practical solution for re-configuring the properties and shapes of slide-ring gels.

QSAR models for describing the toxicological effects of ILs against Staphylococcus aureus based on norm indexes

The hazardous potential of ionic liquids (ILs) is becoming an issue of great concern due to their important role in many industrial fields as green agents. The mathematical model for the toxicological effects of ILs is useful for the risk assessment and design of environmentally benign ILs. The objective of this work is to develop QSAR models to describe the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of ILs against Staphylococcus aureus (S. aureus). A total of 169 and 101 ILs with MICs and MBCs, respectively, are used to obtain multiple linear regression models based on matrix norm indexes. The norm indexes used in this work are proposed by our research group and they are first applied to estimate the antibacterial toxicity of these ILs against S. aureus. These two models precisely and reliably calculated the IL toxicities with a square of correlation coefficient (R²) of 0.919 and a standard error of estimate (SE) of 0.341 (in log unit of mM) for pMIC, and an R² of 0.913 and SE of 0.282 for pMBC.

Preparation of irrefrangible polyacrylamide hybrid hydrogels using water-dispersible cyclotetrasiloxane or polyhedral oligomeric silsesquioxane containing polymerizable groups as cross-linkers

Irrefrangible polyacrylamide hybrid hydrogels were prepared using polymerizable siloxane oligomers as cross-linkers (CyTS-MNa and POSS-MNa, respectively).