Search results for "copolymer"
showing 10 items of 1003 documents
Mass Action Model Applied to the Thermodynamic Properties of Transfer of Nonionic Copolymers from Water to the Aqueous Surfactant Solutions
2003
A thermodynamic model which enables the properties of aqueous copolymer/surfactant mixtures to be fit quantitatively was proposed. Namely, a relationship between the properties of transfer of the unassociated copolymer from water to the aqueous surfactant solutions (DeltaY(t)) and the surfactant concentration was derived. The model was based on the idea that AY, can be expressed in terms of the following contributions: (1) interaction between monomers of copolymer and surfactant, (2) displacement of the monomer-micelle equilibrium induced by the copolymer, (3) formation of the surfactant-copolymer aggregation complex, and (4) formation of the mixed micelles. Such a model was applied to most…
Synthesis of Water-Soluble Copolymers Carrying Long-Chain (C12 to C30 ) Aliphatic Moieties
2011
Water-soluble copolymers from mono-1-alkyl itaconates and N-vinyl-2-pyrrolidone are synthesized and characterized. Themono-1-alkyl itaconates are prepared from itaconic anhydride and the related alcohol: 1-dodecanol, 1-octadecanol, 1-docosanol, and 1-triacontanol. The mono-1-triacontyl itaconate is synthesized fromplant growth regulator policosanols extracted from Agave fourcrouydes, where 1-triacontanol is the major product. The reactivity ratios, calculated according to the Mao-Huglin method for copolymerizations conducted to medium-high conversions, indicate a tendency toward alternation for all copolymerization reactions. Water solubility of copolymers is provided as a function of copol…
A thermodynamic study to evidence the alpha,omega-dichloroalkane/ block copolymer mixed aggregates formation: effect of the copolymer architecture.
2006
Abstract The thermodynamics of α , ω -dichloroalkanes in aqueous solutions of (ethylene oxide)11(propylene oxide)16(ethylene oxide)11 (L35) and (propylene oxide)8(ethylene oxide)23(propylene oxide)8 (10R5) was determined at 298 and 305 K. Modeling the experimental data allowed to calculate the standard free energy ( Δ G D o / w ) and the volume ( Δ V D / w ) for the additive–copolymer mixed aggregates formation per additive molecule. Δ G D o / w for Cl2CH2 and Cl2(CH2)2 evidenced that the process is controlled by the forces exercising between the chlorine atoms and the OH groups of the copolymer micelles protruded into the aqueous phase. Cl2(CH2)3 experiences both the hydrophilic and hydrop…
Aqueous nonionic copolymer-functionalized laponite clay. A thermodynamic and spectrophotometric study to characterize its behavior toward an organic …
2006
The affinity of functionalized Laponite clay toward an organic material in the aqueous phase was explored. Functionalization was performed by using triblock copolymers based on ethylene oxide (EO) and propylene oxide (PO) units that are EO(11)PO(16)EO(11) (L35) and PO(8)EO(23)PO(8) (10R5). Phenol (PhOH) was chosen as organic compound, which represents a contaminant prototype. To this purpose, densities and enthalpies of mixing as well as PhOH UV-absorption spectra were determined. The enthalpy and the spectrophotometry revealed PhOH-Laponite interactions whereas the volume did not. It emerged that the area occupied by PhOH on the Laponite surface is equal to that computed from the partial m…
Aqueous block copolymer-surfactant mixtures and their ability in solubilizing chlorinated organic compounds. A thermodynamic and SANS study.
2006
Within the topic of surfactant enhanced solubilization of additives sparingly soluble in water, volumetric, solubility, conductivity, and small-angle neutron scattering (SANS) experiments on mixtures composed of alpha,omega-dichloroalkane, surfactant, copolymer, and water were carried out at 298 K. The triblock copolymers (ethylene oxide)132(propylene oxide)50(ethylene oxide)132 (F108) and (ethylene oxide)76(propylene oxide)29(ethylene oxide)76 (F68) were chosen to investigate the role of the molecular weight keeping constant the hydrophilic/hydrophobic ratio. The selected surfactants are sodium decanoate (NaDec) and decyltrimethylammonium bromide (DeTAB) with comparable hydrophobicity and …
Solubilization of an Organic Solute in Aqueous Solutions of Unimeric Block Copolymers and Their Mixtures with Monomeric Surfactant: Volume, Surface T…
2008
The ability of aqueous systems, formed by unimeric copolymers and their mixtures with a monomeric surfactant, in solubilizing large quantities of 1-nitropropane (PrNO2) was explored. The copolymers are F68 and L64, which differ for the hydrophilicity, and the surfactant is sodium dodecanoate. For a better understanding of the mechanism of solubilization, thermodynamic (volume and differential scanning calorimetry), spectroscopy (steady-state fluorescence), viscosity, and interfacial investigations were carried out. PrNO2 causes the micellization of the unimeric copolymer, and the required amount of PrNO2 depends on the composition, the copolymer nature, and the temperature. Large quantities…
Volumes of Polar Additives in Aqueous Solutions of the Poly(ethylene oxide)13−Poly(propylene oxide)30− Poly(ethylene oxide)13 Triblock Copolymer at 2…
1999
Density measurements of poly(ethylene oxide)13−poly(propylene oxide)30−poly(ethylene oxide)13 (L64)−water and alcohol−L64−water systems were carried out at 293 and 301 K. The alcohols studied are propanol to pentanol and 2,2,2-trifluoroethanol (F3EtOH) to 2,2,3,3,4,4,4-heptafluorobutanol (F7BuOH). From the experimental data of the water−L64 binary system as functions of L64 concentration (mC), the partial molar volumes of L64 in the standard state and in the aqueous and micellar phases were calculated. At both temperatures L64 micelle is formed by a core of pure polypropylene oxide units and a hydrated shell of poly(ethylene oxide) units. In the case of the ternary systems, the apparent mol…
Micellization and Micellar Structure of a Poly(ethylene oxide)/Poly(propylene oxide)/Poly(ethylene oxide) Triblock Copolymer in Water Solution, As St…
1997
The micellization of the triblock copolymer Pluronic P85 (poly(oxyethylene)27/poly(oxypropylene)39/poly(oxyethylene)27) in aqueous solution was followed vs temperature and addition of aliphatic alcohols, using the spin probe technique. Different types of probes properly chosen (spin-labeled (SL) poly(oxyethylene(4))nonylphenol, SL-Pluronic L62, TEMPO-laurate, TEMPO-hexanoate, CAT 4, CAT 8, CAT 11, CAT 16, and 5-, 7-, 10-, and 12-doxylstearic acids) provided information about the micellar structure (polarity, viscosity, and order degree) at different radial locations. Micellization was found to be low at room temperature, even for 10% aqueous solutions, but strongly increasing with temperatu…
Functionalization of Crosslinked Vesicles by Co-Self-Assembly of a Gelable Diblock Copolymer and Mercaptosilane
2008
Herein, a convenient and general method to simultaneously fix and functionalize polymeric vesicles with sulphydryl groups by the co-self-assembly of poly(ethylene oxide)-block-poly[3-(triethoxysilyl)propyl methacrylate] (PEO-b-PTESPMA) and 3-mercaptopropyltrialkoxysilane in an aqueous solution is reported. The presence of sulphydryl groups across the vesicle membrane has been confirmed by using an energy-filtered technique during TEM analysis and by capturing Au nanoparticles.
Double-Shell Vesicles, Strings of Vesicles and Filaments Found in Crosslinked Micellar Solutions of Poly(1,2-butadiene)-block-poly(ethylene oxide) Di…
2001
Micellar structures of amphiphilic poly(1,2-butadiene)-block-poly(ethylene oxide) diblock copolymers have been crosslinked in aqueous solution by γ-irradiation. By transmission electron microscopy (TEM) of neganively stained specimen it is shown that the precominant structures present are sopolymer sesicles (which appear to be double latered. These fived vesules are stable with respect to their share and can be transferred from water into a good solvent for blue filbeks, such as tetrahydrofuran, this demonstrating the effectiveness of the crosslinking. In addition to the resicles a small number of flexible cylindrichl/filimented structures sequentially fused vesicles/strings of vesicles and…