Association and Phase Behavior of Cholic Acid-Modified Dextran and Phosphatidylcholine Liposomes

The interaction between liposomes (1,2-dimyristoyl-<i>sn</i>-glycero-3-phosphocholine (DMPC)) and a hydrophobically modified water-soluble polymer (HMP; a bile acid-modified dextran) has been investigated by isothermal titration calorimetry (ITC) and differential scanning calorimetry (DSC), combined with turbidity measurement and cryogenic scanning electron microscopy (cryo-SEM). The thermodynamic information on the association (enthalpy of interaction, enthalpy of transition of mixed vesicles to mixed micelle-like aggregates) was obtained from ITC. Further, the phase behavior for the system could be derived from the ITC measurements, and be confirmed by turbidity and cryo-SEM. The effect of cholic acid (CA) side groups on the ordered arrangement of DMPC bilayers was studied by DSC, by following the changes they induce in the gel-to-liquid crystalline liposome phase transition. The DSC results were in excellent agreement with the interpretation proposed for the ITC results. The morphology of the aggregates, as characterized by cryo-SEM, is in line with the proposed aggregate morphologies

Conductivities of 1‑Alkyl-3-methylimidazolium Chloride Ionic Liquids in Disaccharide + Water Solutions at 298.15 K

Conductivities for ionic liquids (ILs) 1-alkyl-3-methylimidazolium chloride ([C_<i>n</i>mim]­Cl, <i>n</i> = 4, 6, 8, 10) + sucrose + water solutions and [C₄mim]­Cl + maltose + water solutions were measured at 298.15 K. Meanwhile, densities, viscosities, and relative permittivities for water + disaccharide mixtures were also measured. The Lee–Wheaton conductivity equation was used to acquire the limiting molar conductivities (Λ₀). The Walden products (Λ₀η₀) were also calculated. The interaction of ILs with disaccharide was discussed in terms of the structure of disaccharides and ILs. Furthermore, values of Λ₀ for inorganic salts (ordinary electrolyte, such as NaCl/KCl) and ILs (special electrolyte) were compared, indicating that they have approximate limiting molar conductivities, namely, they have not too much difference in electrical conductivity

Sodium Fluoride-Assisted Hydrothermal Exfoliation of Graphite into Graphene as Filler of Epoxy Resin Coating To Protect Aluminum

The low yield of graphene in the sonication-assisted aqueous-phase exfoliation is one of the challenges to its large-scale production in industry. Here, we report that hydrothermal exfoliation of graphite into graphene in NaF and polyether F127 (F127) solution can achieve a high concentration (0.55 mg mL–1) or yield (8.2%) of graphene in a low-cost, environmentally friendly manner. The defect of as-exfoliated graphene is comparable to that produced by the sonication-assisted exfoliation. In the exfoliation process, NaF and F127 are regarded as the intercalator and stabilizer. The thermal motion of H2O and F–/Na+ ion pairs, Brownian motion of graphite particles, and thermally agitation of graphite interlayers are the main driving force for exfoliating graphite. In addition, as filler of epoxy resin (EP), the graphene can enhance considerably the anticorrosion performance of EP coating. The hydrothermal exfoliation in NaF and F127 solution provides a new choice for the large-scale production of graphene

Self-Aggregation of Amphiphilic Dendrimer in Aqueous Solution: The Effect of Headgroup and Hydrocarbon Chain Length

The self-aggregation of amphiphilic dendrimers G₁QPAMC_<i>m</i> based on poly­(amidoamine) PAMAM possessing the same hydrophilic group but differing in alkyl chain length in aqueous solution was investigated. Differences in the chemical structures lead to significant specificities in the aggregate building process. A variety of physicochemical parameters presented monotonous regularity with the increase in alkyl chain length in multibranched structure, as traditional amphiphilic molecules. A significant difference, however, existed in the morphology and the microenvironment of the microdomain of the aggregates, with G₁QPAMC_<i>m</i> with an alkyl chain length of 16 intending to form vesicles. To obtain supporting information about the aggregation mechanism, the thermodynamic parameters of micellization, the free Gibbs energy Δ<i>G</i>_mic, and the entropy Δ<i>S</i>_mic were derived subsequently, of which the relationship between the hydrophobic chain length and the thermodynamic properties indicated that the self-assembly process was jointly driven by enthalpy and entropy. Other than traditional surfactants, the contribution of enthalpy has not increased identically to the increase in hydrophobic interactions, which depends on the ratio of the alkyl chain length to the radius in the headgroup. Continuous increases in the hydrophobic chain length from 12 to 16 lead to the intracohesion of the alkyl chain involved in the process of self-assembly, weakening the hydrophobic interactions, and the increase in −Δ<i>H</i>_mic, which offers an explanation of the formation of vesicular structures

Supramolecular Vector/Drug Coassemblies of Polyglycerol Dendrons and Rutin Enhance the pH Response

A coassembly strategy for a supramolecular vector/drug was proposed with a biocompatible ternary dodecyl-bi­(third-generation polyglycerol (PG) dendrons) (C12-(G3)2) amphiphile, dodecyl sulfobetaine (SB3-12) surfactant, and poorly water-soluble drug rutin. C12-(G3)2 and rutin will mutually enhance their pH response by protonation and deprotonation of dendritic PG and rutin’s ionization as the pH changes from the acidic gastric lumen to the weakly alkaline intestine. SB3-12 may increase the payload and bring about sustained release for rutin by intermolecular interactions. Self-assembling behaviors of C12-(G3)2, SB3-12, sodium dodecyl sulfate (SDS), and dodecyl tri­methyl­ammonium bromide (DTAB) and their hybrids with rutin were characterized by UV–vis spectroscopy, a fluorescence probe, and 1H NMR. UV–vis and 1H NMR were used to identify the position and orientation of rutin in the vectors. The functions of the vector/drug were confirmed by measuring the solubility and in vitro release of rutin. The ternary coassembling vector/drug easily imparted functions of pH-responsive and sustained release without complex synthetic processes. The nanocaves framed by PG dendrons in the micelles provide pH-responsive compartments for rutin and SB3-12 in the supramolecular vector/drug anchors that accommodate rutin by weak interactions. The finely matched supramolecular vector/drug coassemblies exhibit the pH-responsive function for a potential application in the treatment of inflammatory bowel disease

Thiosalicylic Acid Modified Graphene Aerogel as Efficient Electrode Material for Ionic Liquid Electrolyte-Based Supercapacitors

Balancing energy density and power density of supercapacitors is highly desired to extend their application range. The development of new electrode materials with efficient electron/ion migration channels and large surface area accessible by the ionic liquid (IL) electrolyte with high stable potential window is a critical way to construct the high-performances of supercapacitors. In this work, a thiosalicylic acid modified graphene aerogel (TGA) was prepared by hydrothermal treatment of a graphene oxide precursor using thiosalicylic acid (TSA) as reductant, sulfur-dopant, and modifier. As-prepared TGA material has hierarchically porous texture with wide pore size distribution range and large accessible surface area by IL electrolytes, which is beneficial to the rapid diffusion and adsorption of IL electrolyte ions with larger ion sizes and high viscosity. Therefore, the TGA material possesses high specific capacitance and rate capability. Using 1-butyl-3-methylimidazolium bis­[(trifluoromethyl)­sulfonyl]­imide ([Bmim]­[Tf2N]) IL electrolyte, the assembled symmetric TGA-based supercapacitor can deliver energy densities of 115–28 Wh kg–1 within power densities of 946–11586 W kg–1. The current work provides a feasible avenue to accomplish the balance between energy density and power density of supercapacitors via the design and synthesis of hierarchically porous graphene aerogels containing doped-heteroatoms and matching with IL electrolyte

Calorimetric and Theoretical Study of the Interaction between Some Saccharides and Sodium Halide in Water

Dilution enthalpies and mixing enthalpies of sodium halide and some saccharides (glucose, galactose, xylose, arabinose, fructose, and sucrose) in aqueous solution were determined by calorimetric measurements at 298.15 K. The values were used to determine enthalpic pair interaction parameters. Combined with Gibbs energy pair parameters, entropic pair interaction parameters were also obtained. Theoretical calculations at the B3LYP/6-311++G­(d,p) level were carried out to provide the information of structures and thermodynamic functions. The information reveals the thermodynamic essence of the interactions between sodium halide and saccharides in aqueous solutions. The experimental results and theoretical calculations show that the sign of enthalpic pair interaction parameter 2<i>υh</i>_ES is determined by the direct interaction between saccharides and ions, whereas the difference in value of 2<i>υh</i>_ES for different saccharides or electrolytes depends on the partial dehydration of saccharides or anions in aqueous solution. The difference in value of entropic pair interaction parameters depends partly on the different dominant interactions in the process of partial dehydration of saccharides or ions. An enthalpy–entropy compensation relationship was observed for the sodium bromide–aldopyranose–water systems. Remarkably, it can be conjectured that the hydration entropy of glucose is lower than for other monosaccharides. Perhaps it is one of the reasons why glucose plays an important role in living organisms rather than other monosaccharides

Enhancing the Bidirectional Reaction Kinetics of Polysulfides by Mott–Schottky-like Electrocatalysts with Rich Heterointerfaces

Designing a well-functional host material to effectively overcome all of the energy barriers in the overall 16-electron sulfur conversion reaction remains elusive in current Li–S batteries (LSBs). Herein, by an advantageous multifunctional integration of immobilization and conversion capability for lithium polysulfides (LiPSs), an N-doped carbon nanobelt (NCB) seeded with ultrafine Mo nanoparticles and MoO2/Mo2C heterostructure (MH-NCB) is prepared for the first time. The target sample of MH-NCB fulfills the smooth bidirectional electrocatalysis of sulfur species in LSBs by the coexistence of enriched heterointerfaces among MoO2/Mo2C and similar “Mott–Schottky” catalysts formed between ultrafine metallic Mo and NCB due to difference in their work functions. The as-obtained MH-NCB harvests an impressive rate capability (593.9 mAh g–1 at 3C) and favorable cycling stability (724.9 mAh g–1 after 500 cycles at 1C) at a high sulfur content of 70.2 wt % in the composite