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Novel results on combustible microemulsions prepared with diesel (D), blends of diesel and rapeseed oil (RSO), and mixtures of eco-friendly amphiphiles are presented. Water solubilization in oil/amphiphile systems was estimated by pseudo-ternary diagrams whereas the phase behavior by Winsor (W) diagrams. The extent of single-phase microemulsion (SPM) area depends on the amphiphile and oil phase composition. The presence of cosurfactant in the anionic-nonionic surfactant mixture increases very much the SPM area, but no effect is observed when half of D is replaced by RSO. In the pseudo-ternary phase diagram, the addition of organic electrolyte decreases the SPM areas. The microemulsions were characterized by the oil/water interfacial tension (gow), and the oil and water solubilization parameters (SPo) and (SPw). The results obtained reveal that the W III microemulsions have minimal goow values, whereas SPo and SPw are maximal. The work connects the phase behavior with the interfacial tension and the solubilization parameters of oil and water and is useful for obtaining and developing optimal microemulsions as alternative fuels.

The collagen hydrolysate (HC) and silver nanoparticles (AgNPs) effect on the mechanical, thermal, in vitro degradation, cytotoxicity and antifungal properties of polylactic acid (PLA) plast...

To initiate our research into the development of biocompati&icirc, le gelled-microemulsions based on essential oils (EOs) and sucrose esters (SEs) for the topical delivery of fluconazole, this formulation study investigated the usefulness of two relatively harmless natural non-ionic surfactants from the group of SEs (sucrose laurate and stearate) to form, in the presence of antifungal EOs, stable, isotropic microemulsions effective on fluconazole solubilization. Fluconazole&rsquo, s solubility in EO significantly depended on their chemical composition, showing higher values for cinnamon, oregano and clove essential oils, further selected as oil phase components for microemulsion formulations. The phase behavior of several EO&ndash, isopropyl miristate/SE&ndash, isopropanol/water systems was assessed through pseudo-ternary phase diagrams constructed by microplate dilution technique. The hydrocarbon chain length of the SE and EO type strongly influenced the size of the microemulsion region in the pseudo-ternary phase diagrams. Ten microemulsion formulations containing 2% fluconazole, 6% or 10% oil mixture of EO&ndash, isopropyl myristate in 1:1 ratio, 45% SE-isopropanol mixture and water, were selected and evaluated for physicochemical properties (droplet size, polydispersity, viscosity, refractive index, zeta potential and pH). All formulations were physicochemically acceptable, but viscosity enhancement and further in vitro and in vivo tests are required for the development of biocompatible, clinically safe and effective fluconazole topical preparations.

Linear and hyperbranched polyglycidol (LPGL and HPGL) with average molecular weight of a few thousands were studied in water and surfactant solutions. The employed surfactants are hexaethyleneglycol mono n -dodecyl ether (C 12 E 6 ), cetyl trimethyl ammonium bromide (CTAB) and sodium dodecyl sulfate (SDS). The working methods are surface tension, steady-state fluorescence, dynamic light scattering (DLS), electrokinetic potential and FTIR spectroscopy. The linear polyglycidols are weakly associative species, unlike the hyperbranched one which is more hydrophilic and harder associates. The linear polymers most efficiently interact with the anionic surfactant, followed by cationic and most weakly with the nonionic. The hydrodynamic diameters of the investigated polyglycidols depend on their structure and molecular weight. In the presence of SDS, the hydrodynamic diameters vary with surfactant concentration. The study reveals the solubilization of fluorescent probes (pyrene, naphthalene) inside the polyglycidol aggregates. Unlike the LPGL, the presence of cavities in HPGL macromolecule offers supplementary “pockets” for solubilization.

The paper reports the natural aging of polyelectrolyte multilayers containing sodium hydrophobically modified poly(acrylates) (PAC n Na, n = 10 and 18) or complexes of PAC n Na with alkyltrimethylammonium bromides (C x TAB, x = 10, 12, 14, 18) and poly(diallyldimethylammonium chloride) (PDADMAC). Wettability, thickness and surface morphology of aged multilayers are compared with those of freshly made. Contact angle (CA) increases with the alkyl chain length of the PAC n Na and of the C x TAB in the complex with PAC n Na. Wettability measurements unveil that only five bilayers of alternatively deposited PAC 18 Na-C 18 TAB and PDADMAC reach in 12 months the same CA as sixty freshly prepared bilayers. The PDADMAC outer layer gives higher CA and root mean square roughness than the negatively terminated multilayers. The results are significant for gaining new insight into the underlying mechanism of multilayers aging, saving materials, and improving the surface coatings for long term preservation.

The study sheds light on the interaction between chitosan (Ch) and polyglycidol (PGL) and uses their interpolymer complex in hydrophilic coating of iron oxide particles (M). Preliminary investigations were performed by modeling chitosan and polyglycidol chains interactions using coarse grained beads approximation and molecular dynamics simulations. The results revealed that Ch and PGL chains associate together forming weak strength complexes, which was experimentally confirmed by surface tension, fluorescence and FTIR. The Ch-PGL mixture (C) and sodium dodecylsulfate (S) were used for layer-by-layer preparation of hydrophilic multilayer coatings of M. The successful covering, demonstrated by DLS, Zeta potential, FTIR, EDAX, preserved the particles super-paramagnetic properties. The most stable multilayer nanocomposite (MSCS) efficiently adsorbed methylene blue from water. The Freundlich model fitted well the equilibrium isotherm data, indicating a heterogeneous, multilayer adsorption. Benefiting from both nano-size and magnetic properties, this adsorbent could be an effectively, cheaply and eco-friendly wastewater treatment means.

The nanofiltration composite membranes were obtained by incorporation of KIT-6 ordered mesoporous silica, before and after its functionalization with amine groups, into polyphenylene-ether-ether-sulfone (PPEES) matrix. The incorporation of silica nanoparticles into PPEES polymer matrix was evidenced by FTIR and UV–VIS spectroscopy. SEM images of the membranes cross-section and their surface topology, evidenced by AFM, showed a low effect of KIT-6 silica nanoparticles loading and functionalization. The performances of the obtained membranes were appraised in permeation of Chaenomeles japonica fruit extracts and the selective separation of phenolic acids and flavonoids. The obtained results proved that the PPEES with functionalized KIT-6 nanofiltration membrane, we have prepared, is suitable for the polyphenolic compound’s concentration from the natural extracts.

The present study demonstrates the hydrophobic effect of poly(electrolyte) multilayer films when they are alkyl-grafted and complexed or not with surfactants. For this purpose, sodium hydrophobically modified poly(acrylates) (PACnNa, n = 10, 18) or their anionic complexes with alkyltrimethylammonium bromides (CxTAB, x = 10, 12, 14, 18), and the cationic poly(diallyldimethyldiammonium chloride) (PDDAMAC) are assembled by layer-by-layer deposition on a glass substrate. Contact angle (CA) measurements reveal that films constructed with PACnNa-CxTAB/PDADMAC are superior water repellants than those of PACnNa/PDADMAC. For example, the highest CA is obtained for the PAC18Na-C18TAB/PDADMAC. Moreover, it has been observed that the CA increases with the alkyl chain length of PACnNa and of surfactant. The film roughness and thickness have the same trend as wettability. Thinner and less coarse films are obtained by NaCl addition, as witnessed by SEM and AFM.

The water–oil interface of AOT/water/isooctane reverse micelles, with different hydration degrees (w0), is investigated by nonradiative energy transfer (NRET) between naphthalene (Np) probe and pyrene grafted poly(acrylic acid) (PAA150-Py32). The polymer is water-soluble while Np has affinity for the organic solvent. UV–Vis spectroscopy reveals that PAA150-Py32 is constrained in the micellar nanocage. The change of the pH of the micellar core and the addition of electrolyte are considered. FTIR and static fluorescence measurements confirm the presence of the polymer at the micellar interface. The stability and size distribution of the reverse micelles, with or without PAA150-Py32 and electrolyte are characterized by DLS. The photophysical parameters of PAA150-Py32 (the polarity index, I1/I3 and the polymer conformation index, IE/IM) are determined at different pHs and electrolyte concentrations. For w0 = 10 and w0 = 15, the pH does not influence the formation of Py excimers, which is an atypical behavior. NRET is strongly dependent on the pH, and for w0 = 10 and pH = 3.6 it reaches a maximum. The optimal salt concentration for which NRET is maximal is 5 × 10− 4 M NaCl. The acquired results shed more light upon the stability of the micellar interface in various experimental conditions.

Multilayer films from hydrophobically modified poly(acrylic acid) (HMPA) and their complexes with cationic surfactants were successfully prepared using the layer-by-layer (LbL) method. Alkyl trimethylammonium bromide derivatives with various lengths of the hydrophobic chain (C10&ndash, C18) were used to interact with the HMPA polymer, generating highly hydrophobic domains in the films and contributing to the antimicrobial properties of the prepared coating. The antimicrobial efficiency against common pathogens such as Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans was investigated in relationship with the morphology and composition of the thin films. The wettability and roughness of the multilayered systems were evaluated using atomic force microscopy (AFM) and contact angle measurements. The effects of the microbial exposure on the surface properties of the prepared films were investigated in order to assess the stability of the HMPA-deposited multilayers and the durability of the antimicrobial activity. The hydrophobically modified films exhibited antimicrobial activity against the studied pathogens. The best efficiency was registered in the case of S. aureus, which showed an inhibition of growth up to 100% after 2 h. C. albicans proved to be less sensitive to the effect of the multilayers deposited from HMPA&ndash, surfactant complexes. These results suggest that HMPA and HMPA&ndash, surfactant complex LbL multilayer films can be used as promising materials in antimicrobial surface coatings with increased resistance to pathogens during exposure.