Search results for "surface"
showing 10 items of 9345 documents
Physicochemical Properties of Copper(II) Bis(2-ethylhexyl) Sulfosuccinate Reversed Micelles
1998
Abstract Measurements of some physicochemical properties (density, viscosity, conductance, UV–vis spectra, IR spectra) of the water/copper(II) bis(2-ethylhexyl) sulfosuccinate (Cu(DEHSS) 2 )/CCl 4 microemulsions, at a fixed surfactant molal concentration ([Cu (DEHSS) 2 ] = 0.05003 mol kg −1 ), as function of the molar ratio R ( R = [water]/[DEHSS − ]) have been performed at 25°C. Information on some structural and dynamical properties of the water-containing Cu(DEHSS) 2 reversed micelles and of their evolution with R are derived from the experimental results. The comparison with the same properties of water-containing sodium bis(2-ethylhexyl) sulfosuccinate reversed micelles allows to evide…
FT-IR and nuclear overhauser enhancement study of the state of urea confined in AOT-reversed micelles
2003
Abstract The system urea/sodium-bis(2-ethylhexyl)sulfosuccinate (AOT) dispersed in CCl 4 and benzene-d6 was investigated by viscosimetry, FT-IR and high-resolution 1 H NMR spectroscopy, as a function of urea/AOT molar ratio ( R urea ) at fixed AOT molal concentration (0.3467 mol kg −1 ) and as a function of AOT concentration at fixed R urea (0.5) at 25 °C. The experimental data are consistent with the hypothesis that urea is encapsulated as small-size hydrogen-bonded cluster in the hydrophilic micellar core of the AOT-reversed micelles and that this structure is maintained well above the volume fraction of the dispersed phase, where a percolative transition occurs. Intermolecular nuclear ov…
Morphology and Rheology of HDPE/LCP Blends Compatibilized by a Novel PE-g-LCP Copolymer
1999
A novel graft copolymer (PE-g-LCP) consisting of polyethylene (PE) backbones and liquid crystalline polymer (LCP) branches was synthesized via reactive blending of an acrylic acid-functionalized PE (Escor 5000 by Exxon) with a semiflexible LCP (SBH 1 : 1 : 2 by Eniricerche S.p.A.). The crude reactive blending product (COP) was shown by investigation of the fractions soluble in boiling toluene and xylene and of the residue to contain unreacted Escor and SBH, together with the graft copolymer forming the interphase. The compatibilizing activity of COP for PE/SBH blends, compared to that of pure Escor, was investigated using two PE grades. The COP addition into 80/20 PE/SBH blends caused a muc…
Loading of polymer nanocarriers: Factors, mechanisms and applications
2014
Abstract The progress in synthetic polymer chemistry has allowed the precise design of hybrid and multifunctional colloidal particles, which differ in type, size and shape, thus enhancing their possible applications as target-oriented carriers of low and high molar mass active species. This survey discusses the basic principles and factors, associated with the process of loading of polymeric nanoparticles. For the purpose of this review, the polymeric nano-carriers are divided into five most studied types: micelles, nanogels, capsules (incl. vesicles), dendrimers, and hybrid nanoparticles with porous cores. Factors influencing the loading are described and their importance discussed. An imp…
Viscosity-molecular weight relationship for cellulose solutions in either NMMO monohydrate or cuen
2010
The intrinsic viscosities, [η], of nine cellulose samples, with molar masses from 50 × 103 to 1 390 × 103 were determined in the solvents NMMO*H2O (N-methyl morpholin N-oxide hydrate) at 80°C and in cuen (copper II-ethlenediamine) at 25°C. The evaluation of these results with respect to the Kuhn–Mark–Houwink relations shows that the data for NMMO*H2O fall on the usual straight line in the double logarithmic plots only for M ≤ 158 103; the corresponding [η]/M relation reads log ([η]/mL g−1) = –1.465 + 0.735 log M. Beyond that molar mass [η] remains almost constant up to M ≈ 106 and increases again thereafter. In contrast to NMMO*H2O the cellulose solutions in cuen behave normal and the Kuhn–…
Self-assembly and anion encapsulation properties of cavitand-based coordination cages.
2001
Two novel classes of cavitand-based coordination cages 7a--j and 8a--d have been synthesized via self-assembly procedures. The main factors controlling cage self-assembly (CSA) have been identified in (i) a P--M--P angle close to 90 degrees between the chelating ligand and the metal precursor, (ii) Pd and Pt as metal centers, (iii) a weakly coordinated counterion, and (iv) preorganization of the tetradentate cavitand ligand. Calorimetric measurements and dynamic (1)H and (19)F NMR experiments indicated that CSA is entropy driven. The temperature range of the equilibrium cage-oligomers is determined by the level of preorganization of the cavitand component. The crystal structure of cage 7d r…
Experimental design approach in the synthesis of molecularly imprinted polymers specific for iprodione fungicide
2015
International audience; An experimental design (ED) approach was applied to study the weight of three factors in the synthesis of a molecularly imprinted polymer (MIP) specific for iprodione fungicide. The objective was to obtain a high specific polymer with the best performance of iprodione binding. Thirteen iprodione-imprinted polymers and 13 non-imprinted polymers (NIP) were synthesized according to ED having 3 influencing factors: the polymerization method, the crosslinker nature and the functional monomer type. For each factor, two levels were studied: bulk and precipitation polymerization for the first factor, trimethylolpropane trimethacrylate (TRIM) and ethylene glycol dimethacrylat…
Functional end groups for polymers prepared using ring-opening metathesis polymerization.
2011
The precise placement of functional groups on the chain-ends of macromolecules is a major focus of polymer research. Most common living polymerization techniques offer specific methods of end-functionalization governed by the active propagating species and the kinetics of the polymerization reaction. Ring-opening metathesis polymerization has established itself as one of the most functional-group-tolerant living polymerization techniques known, but this tolerance has limited the number of available functionalization reactions. Metathesis chemists have therefore been required to develop a variety of end-functionalizations, adapting each of them to the reactivity scheme of the particular cata…
Polymeric gegenions induced variability and mobility of amphiphilic supramolecular structures on solid substrates
1992
Abstract The micromorphological variations of amphiphilic L -glutamate derivatives at air-substrate interfaces due to an adjacent mobile polymer matrix have been investigated via fluorescence microscopy. Adjusted monolayers of the L -glutamate derivatives have been transferred by LB technique out of different aggregation states onto various substrates. The substrates have been prepared by successive polymer preadsorption to the solid support. The influence of the adjacent polymer layers on the domain morphology as a function of water content and temperature has been examined intensively. Moreover, reversible domain changes induced by temperature variation of the transferred films have been …
Synthesis and bio-functionalization of magnetic nanoparticles for medical diagnosis and treatment
2011
The synthesis of multifunctional magnetic nanoparticles (NPs) is a highly active area of current research located at the interface between materials science, biotechnology and medicine. By virtue of their unique physical properties magnetic nanoparticles are emerging as a new class of diagnostic probes for multimodal tracking and as contrast agents for MRI. Furthermore, they show great potential as carriers for targeted drug and gene delivery, since reactive agents, such as drug molecules or large biomolecules (including genes and antibodies), can easily be attached to their surface. On the other hand, the fate of the nanoparticles inside the body is mainly determined by the interactions wi…