Optimizing the Ion Conductivity and Mechanical Stability of Polymer Electrolyte Membranes Designed for Use in Lithium Ion Batteries: Combining Imidazolium-Containing Poly(ionic liquids) and Poly(propylene carbonate).

State-of-the-art Li batteries suffer from serious safety hazards caused by the reactivity of lithium and the flammable nature of liquid electrolytes. This work develops highly efficient solid-state electrolytes consisting of imidazolium-containing polyionic liquids (PILs) and lithium bis(trifluoromethane sulfonyl)imide (LiTFSI). By employing PIL/LiTFSI electrolyte membranes blended with poly(propylene carbonate) (PPC), we addressed the problem of combining ionic conductivity and mechanical properties in one material. It was found that PPC acts as a mechanically reinforcing component that does not reduce but even enhances the ionic conductivity. While pure PILs are liquids, the tricomponent PPC/PIL/LiTFSI blends are rubber-like materials with a Young's modulus in the range of 100 MPa. The high mechanical strength of the material enables fabrication of mechanically robust free-standing membranes. The tricomponent PPC/PIL/LiTFSI membranes have an ionic conductivity of 10-6 S·cm-1 at room temperature, exhibiting conductivity that is two orders of magnitude greater than bicomponent PPC/LiTFSI membranes. At 60 °C, the conductivity of PPC/PIL/LiTFSI membranes increases to 10-5 S·cm-1 and further increases to 10-3 S·cm-1 in the presence of plasticizers. Cyclic voltammetry measurements reveal good electrochemical stability of the tricomponent PIL/PPC/LiTFSI membrane that potentially ranges from 0 to 4.5 V vs. Li/Li+. The mechanically reinforced membranes developed in this work are promising electrolytes for potential applications in solid-state batteries.

High-Resolution Tracking of Multiple Distributions in Metallic Nanostructures: Advanced Analysis Was Carried Out with Novel 3D Correlation Thermal Field-Flow Fractionation.

Multifunctional metallic nanostructures are essential in the architecture of modern technology. However, their characterization remains challenging due to their hybrid nature. In this study, we present a novel photoreduction-based protocol for augmenting the inherent properties of imidazolium-containing ionic polymers (IIP)s through orthogonal functionalization with gold nanoparticles (Au NPs) to produce IIP_Au NPs, as well as novel and advanced characterization via three-dimensional correlation thermal field-flow fractionation (3DCoThFFF). Coordination chemistry is applied to anchor Au3+ onto the nitrogen atom of the imidazolium rings, for subsequent photoreduction to Au NPs using UV irradiation. Thermal field-flow fractionation (ThFFF) and the localized surface plasmon resonance (LSPR) of Au NPs are both dependent on size, shape, and composition, thus synergistically co-opted herein to develop mutual correlation for the advanced analysis of 3D spectral data. With 3DCoThFFF, multiple sizes, shapes, compositions, and their respective distributions are synchronously correlated using time-resolved LSPR, as derived from multiple two-dimensional UV-vis spectra per unit ThFFF retention time. As such, higher resolutions and sensitivities are observed relative to those of regular ThFFF and batch UV-vis. In addition, 3DCoThFFF is shown to be highly suitable for monitoring and evaluating the thermostability and dynamics of the metallic nanostructures through the sequential correlation of UV-vis spectra measured under incremental ThFFF temperature gradients. Comparable sizes are measured for IIP and IIP_Au NPs. However, distinct elution profiles and UV-vis absorbances are recorded, thereby reaffirming the versatility of ThFFF as a robust tool for validating the successful functionalization of IIP with Au to produce IIP_Au NPs.

Engineering exosome polymer hybrids by atom transfer radical polymerization.

Exosomes are emerging as ideal drug delivery vehicles due to their biological origin and ability to transfer cargo between cells. However, rapid clearance of exogenous exosomes from the circulation as well as aggregation of exosomes and shedding of surface proteins during storage limit their clinical translation. Here, we demonstrate highly controlled and reversible functionalization of exosome surfaces with well-defined polymers that modulate the exosome's physiochemical and pharmacokinetic properties. Using cholesterol-modified DNA tethers and complementary DNA block copolymers, exosome surfaces were engineered with different biocompatible polymers. Additionally, polymers were directly grafted from the exosome surface using biocompatible photo-mediated atom transfer radical polymerization (ATRP). These exosome polymer hybrids (EPHs) exhibited enhanced stability under various storage conditions and in the presence of proteolytic enzymes. Tuning of the polymer length and surface loading allowed precise control over exosome surface interactions, cellular uptake, and preserved bioactivity. EPHs show fourfold higher blood circulation time without altering tissue distribution profiles. Our results highlight the potential of precise nanoengineering of exosomes toward developing advanced drug and therapeutic delivery systems using modern ATRP methods.

Thermal Field-Flow Fractionation with Quintuple Detection for the Comprehensive Analysis of Complex Polymers.

With a constantly increasing complexity of macromolecular structures, advanced polymer analysis faces new challenges with regard to the comprehensive analysis of these structures. Today it goes without saying that comprehensive polymer analysis requires selective and robust fractionation methods in combination with a set of information-rich detectors. Thermal field-flow fractionation (ThFFF) has proven to be a powerful technique for the fractionation of complex polymers as well as polymer assemblies. In the present study, ThFFF is coupled to a set of five detectors to simultaneously provide quantitative information on a number of important molecular parameters, including molar mass, molecular size, chemical composition, molecular topology, intrinsic viscosity, and normal and thermal diffusion coefficients. The five-detector setup includes a triple detector device (multiangle light scattering (MALS), differential refractive index (dRI), and differential viscometer (dVis)) that is coupled to an ultraviolet (UV) detector for dual concentration detection and an online dynamic light scattering (DLS) detector. Triple detection consisting of MALS, dRI, and dVis provides information on molar mass, molecular size, and molecular topology. Dual concentration detection offers compositional analysis from a combination of UV and dRI detectors, whereas DLS provides information on diffusion coefficients and hydrodynamic radii. The power of this novel quintuple detector ThFFF (ThFFF-QD) is documented for three important fields of application, namely, the comprehensive analysis of (1) linear and star-shaped polymers, (2) hydrogenated and deuterated polymers, and (3) block copolymer self-assemblies. These applications highlight the novel approach of determining the most relevant molecular parameters, including Mark-Houwink and conformation plots, simultaneously in a single experiment.

Stereocomplexation of Polymers in Micelle Nanoreactors As Studied by Multiple Detection Thermal Field-Flow Fractionation.

In this study the thermally induced in situ stereocomplexation (SC) of binary blends of symmetrical isotactic and syndiotactic polymethymethacrylates (i- and s-PMMAs) inside micellar nanoreactors (MNR) with polystyrene (PS) shells is investigated using thermal field-flow fractionation (ThFFF) as a separation technique. The MNRs are prepared from three systematic binary blending ratios of pure micelles of i-PMMA-PS and s-PMMA-PS in a nonsolvent for PMMAs in order to produce mixed micelles with a binary microstructural composition of the interior PMMA cores. The SC of these stereoregular PMMA cores inside the MNRs is shown to be thermally induced as a function of annealing temperatures from room temperature up to 150 °C. This SC is initially confirmed by Fourier transform infrared spectroscopy (FTIR), whereby signal shifts are observed in the carbonyl absorption regions. These signal shifts are as a result of SC interactions between adjacent ester and alpha-methyl groups. Furthermore, temperature-dependent dynamic light scattering (DLS) results show that MNRs with more SC domains have a much more drastic reduction in size. Additional corroboration is provided by multiple detection ThFFF results which show significant differences in retentions and sizes between MNRs with stereocomplexed cores and those without. Ratios of i-PMMA:s-PMMA in the order of 1:1, 1:2, and 2:1 were investigated with all ratios exhibiting thermal annealing induced SC, of which the 1:2 ratio is shown to have the highest predisposition to SC.

Characterization of Complex Polymer Self-Assemblies and Large Aggregates by Multidetector Thermal Field-Flow Fractionation.

Micelles prepared from amphiphilic block copolymers (ABCs) have found numerous applications in pharmaceutical, electronics, environmental, cosmetics, and hygiene industries. These micelles, whether in the pure or mixed micelle form, often exist as multiple morphologies (spherical, cylindrical, worm, or vesicular) in equilibrium with each other. However, none of the current column-based fractionation techniques or any microscopic technique are capable of a successful separation, identification, and quantitation of these complex self-assemblies with regards to morphology, size, molar mass, and chemical composition in one experiment. Multidetector thermal field-flow fractionation (ThFFF) is shown to be capable of separating and characterizing not only pure micelles but also mixed micelles prepared from polystyrene-poly(ethylene oxide) ABCs. In addition, multidetector ThFFF is demonstrated to be capable of successfully characterizing multiple micellar morphological evolutions (induced by the addition of an electrolyte) and thus showcasing the potential of this novel approach to monitor the formation of polymer self-assemblies with multiple and complex morphological distributions.