Amphiphilic polymer conetworks (APCN) were prepared in N,N-dimethylformamide (DMF) by the interconnection of four-arm star poly(vinylidene fluoride) (PVDF, M n = 8800 Da) end-functionalized with benzaldehyde groups and four-arm star poly(ethylene glycol) (PEG, M n = 10 kDa) end-functionalized with benzaacylhydrazide groups. The PVDF stars were prepared via the reversible addition−fragmentation chain transfer polymerization of vinylidene fluoride using a tetraxanthate chain transfer agent. Equilibrium swelling of the APCNs in various solvents was dependent on the compatibility of the APCN components with the solvent, with the degrees of swelling (DS) varying from 22 in DMF (a good solvent for both PEG and PVDF), down to 8 in water (a good and selective solvent for PEG), and even down to 3 in diethyl ether (a nonsolvent for both polymers). Characterization of the conetworks in D 2 O using small-angle neutron scattering (SANS) indicated phase separation at the nanoscale, as evidenced by a (broad) correlation peak, consistent with a 19 nm spacing between the formed PVDF-based hydrophobic clusters of ∼10 nm diameter and an aggregation number of ca. 50 (growing in size with PVDF content). This behavior was independent of temperature from 25 to 70 °C and slightly dependent on deviations (±ca. 50 mol %) from the PVDF: PEG stoichiometry. Conetwork characterization in the bulk using atomic force microscopy (AFM) revealed a domain spacing of 14 ± 6 nm, in good agreement with the spacing of 11 nm calculated from the SANS results above (19 nm) but also taking into account the DS in D 2 O (5.5).Annealing the conetworks at 200 °C, a temperature above the melting point of PVDF, did not improve the morphological order in the AFM images. Finally, APCNs prepared in the room temperature ionic liquid binary mixture lithium bis(trifluoromethanesulfonyl)imide:1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (1:9 molar ratio) exhibited an electrochemical stability up to 4.3 V and a good room temperature ion conductivity of 0.6 mS cm −1 .
Microemulsions, as thermodynamically stable mixtures of oil, water, and surfactant, are known and have been studied for more than 70 years. However, even today there are still quite a number of unclear aspects, and more recent research work has modified and extended our picture. This review gives a short overview of how the understanding of microemulsions has developed, the current view on their properties and structural features, and in particular, how they are related to applications. We also discuss more recent developments regarding nonclassical microemulsions such as surfactant-free (ultraflexible) microemulsions or ones containing uncommon solvents or amphiphiles (like antagonistic salts). These new findings challenge to some extent our previous understanding of microemulsions, which therefore has to be extended to look at the different types of microemulsions in a unified way. In particular, the flexibility of the amphiphilic film is the key property to classify different microemulsion types and their properties in this review. Such a classification of microemulsions requires a thorough determination of their structural properties, and therefore, the experimental methods to determine microemulsion structure and dynamics are reviewed briefly, with a particular emphasis on recent developments in the field of direct imaging by means of electron microscopy. Based on this classification of microemulsions, we then discuss their applications, where the application demands have to be met by the properties of the microemulsion, which in turn are controlled by the flexibility of their amphiphilic interface. Another frequently important aspect for applications is the control of the rheological properties. Normally, microemulsions are low viscous and therefore enhancing viscosity has to be achieved by either having high concentrations (often not wished for) or additives, which do not significantly interfere with the microemulsion. Accordingly, this review gives a comprehensive account of the properties of microemulsions, including most recent developments and bringing them together from a united viewpoint, with an emphasis on how this affects the way of formulating microemulsions for a given application with desired properties.
We provide here a general view on the interactions of surfactants with viruses, with a particular emphasis on how such interactions can be controlled and employed, for inhibiting the infectivity of enveloped viruses, including coronaviruses. The aim is to provide to interested scientists from different fields, including chemistry, physics, biochemistry, and medicine, an overview over the basic properties of surfactants and (corona)viruses, which are relevant to understanding the interactions between the two. Various types of interactions between surfactant and virus are important, and they act on different components of a virus such as the lipid envelope, membrane (envelope) proteins and nucleo-capsid proteins. Accordingly, this cannot be a detailed account of all relevant aspects, but instead a summary that bridges between the different disciplines. We describe concepts and cover a selection of the relevant literature as an incentive for diving deeper into the relevant material. Our focus is on more recent developments around the COVID-19 pandemic caused by SARS-CoV-2, applications of surfactants against the virus, and on the potential future use of surfactants for pandemic relief. However, we also cover the most important aspects of the historical development of using surfactants in combatting virus infections. We conclude that surfactants are already playing very important roles in various directions of defence against viruses, either directly, as in disinfection, or as carrier components of drug delivery systems for prophylaxis or treatment. By designing tailor-made surfactants and, consequently, advanced formulations, one can expect a more and more effective use of surfactants, either directly as antiviral compounds or as part of more complex formulations.
A series of metal-mediated cages, having multiple cavities, was synthesized from Pd cations and tris- or tetrakis-monodentate bridging ligands and characterized by NMR spectroscopy, mass spectrometry, and X-ray methods. The peanut-shaped [Pd L ] cage deriving from the tris-monodentate ligand L could be quantitatively converted into its interpenetrated [5Cl@Pd L ] dimer featuring a linear {[Pd-Cl-] Pd} stack as an unprecedented structural motif upon addition of chloride anions. Small-angle neutron scattering (SANS) experiments showed that the cigar-shaped assembly with a length of 3.7 nm aggregates into mono-layered discs of 14 nm diameter via solvophobic interactions between the hexyl sidechains. The hepta-cationic [5Cl@Pd L ] cage was found to interact with polyanionic oligonucleotide double-strands under dissolution of the aggregates in water, rendering the compound class interesting for applications based on non-covalent DNA binding.
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