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Micelle Concentration (micelle + concentration)
Kinds of Micelle Concentration Selected AbstractsSystem peaks in micellar electrophoresis: I. Utilization of system peaks for determination of critical micelle concentrationELECTROPHORESIS, Issue 5 2008Jana Lokajová Abstract A new way to determine the critical micelle concentration (CMC) based on the mobilities of system peaks is presented. A general approach for the CMC determination is based on the change of the slope or on finding the inflection point in the plot of a physical property of solution as a function of surfactant concentration. The determination of CMC by system peaks in CE utilizes a "jump" instead of a continuous change in the measured quantity. This phenomenon was predicted by the program PeakMaster, which was modified for simulation of micellar systems. The simulation of the steep change in mobilities of the anionic system peaks showing the CMC value was verified experimentally in a set of measurements, where the concentration of the surfactant was varied while the ionic strength was kept constant. The experimental work fully proved our model. A comparative electric current measurement was carried out. The proposed method seems to offer easier CMC determination as compared to the standard methods. [source] Enantioselectivity of alcohol-modified polymeric surfactants in micellar electrokinetic chromatographyELECTROPHORESIS, Issue 15 2003Jepkoech Tarus Abstract A novel method of modifying sodium undecanoyl- L -leucinate (SUL) micelles employed in chiral separation of analytes in micellar electrokinetic chromatography (MEKC) to enhance selectivity toward specific analytes is discussed. The current study aimed at modifying the SUL micelles by introducing different alcohols into the mono-SUL micelles. The micellar solutions were then polymerized in the presence of alcohols followed by postpolymerization extraction of the alcohols to yield alcohol-free polymeric surfactants (poly- L -SUL). The effects of hexanol (C6OH) and undecylenyl alcohol (C11OH) on micellar properties of this surfactant were investigated by use of surface tensiometry, fluorescence spectroscopy, pulsed field gradient-nuclear magnetic resonance (PFG-NMR), and MEKC. The surface tension and PFG-NMR studies indicated an increase in the critical micelle concentration (cmc) and micellar size upon increasing the alcohol concentration. Fluorescence measurements suggested that alcohols induce closely packed micellar structures. Coumarinic and benzoin derivatives, as well as (±)-1, 1'-binaphthyl-2,2'-dihydrogen phosphate (BNP) were used as test analytes for MEKC experiments. Examination of MEKC data showed remarkable resolutions and capacity factors of coumarinic derivatives obtained with modified poly- L -SUL as compared to the unmodified poly- L -SUL. Evaluation of fluorescence, PFG-NMR, and MEKC data suggest a strong correlation between the polarity and hydrodynamic radii of alcohol-modified micelles and the resolution of the test analytes. [source] Polymeric alkenoxy amino acid surfactants: I. Highly selective class of molecular micelles for chiral separation of ,-blockersELECTROPHORESIS, Issue 15 2003Syed A. A. Rizvi Abstract Two amino acid-based alkenoxy micelle polymers were synthesized for this study. These include polysodium N -undecenoxy carbonyl- L -leucinate (poly- L -SUCL) and polysodium N -undecenoxy carbonyl- L -isoleucinate (poly- L -SUCIL). The polymerization time and concentration of the synthesized micelle polymers were optimized by 1H-nuclear magnetic resonance (NMR) and capillary electrophoresis (CE) experiments. Detailed physicochemical properties (1H NMR, critical micelle concentration (CMC), optical rotation, partial specific volume, aggregation number, and polarity) were determined, and these molecular micelles were introduced as a pseudostationary phase in micellar electrokinetic chromatography to study the molecular recognition and to develop a method for simultaneous separation of eight chiral ,-blockers. It is found that poly- L -SUCL gives overall better chiral resolution and wider chiral window than poly- L -SUCIL. After optimizing the type of micelle polymer, injection size and temperature, simultaneous separation and enantioseparation of eight ,-blockers were achieved in less than 35 min. A comparison with the amide-type surfactants of the same polar head group and alkyl chain length showed that carbamate-type surfactants always work better than the corresponding amide-type surfactant. [source] Bioavailability of solid and non-aqueous phase liquid (NAPL)-dissolved phenanthrene to the biosurfactant-producing bacterium Pseudomonas aeruginosa 19SJENVIRONMENTAL MICROBIOLOGY, Issue 9 2001Marta García-Junco The biodegradation of phenanthrene by the biosurfactant-producing strain Pseudomonas aeruginosa 19SJ was investigated in experiments with the compound present either as crystals or dissolved in non-aqueous phase liquids (NAPLs). Growth on solid phenanthrene exhibited an initial phase not limited by dissolution rate and a subsequent, carbon-limited phase caused by exhaustion of the carbon source. Rhamnolipid biosurfactants were produced from solid phenanthrene and appeared in solution and particulate material (cells and phenanthrene crystals). During the carbon-limited phase, the concentration of rhamnolipids detected in culture exceeded the critical micelle concentration (CMC) determined with purified rhamnolipids. The biosurfactants caused a significant increase in dissolution rate and pseudosolubility of phenanthrene, but only at concentrations above the CMC. Externally added rhamnolipids at a concentration higher than the CMC increased the biodegradation rate of solid phenanthrene. Mineralization curves of low concentrations of phenanthrene initially dissolved in two NAPLs [2,2,4,4,6,8,8-heptamethylnonane and di(2-ethylhexyl)phthalate] were S-shaped, although no growth was observed in the population of suspended bacteria. Biosurfactants were not detected in solution under these conditions. The observed mineralization was attributed not only to suspended bacteria, but also to bacterial populations growing at the NAPL,water interface, mineralizing the compound at higher rates than predicted by abiotic partitioning. We suggest that rhamnolipid production and attachment increased the bioavailability of phenanthrene, so promoting biodegradation activity. [source] Synthesis and characterization of imidazolinium surfactants derived from tallow fatty acids and diethylenetriamineEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 10 2008Divya Bajpai Abstract This paper describes the synthesis of long-chain dialkylamido imidazolines based on tallow fatty acids and diethylenetriamine, followed by their quaternization. Imidazolines were obtained by non-solvent microwave synthesis using calcium oxide as support, which were then quaternized by using dimethyl sulfate as a quaternizing agent and iso -propanol as a solvent, to produce cationic imidazolinium salts. The synthesized cationic imidazoline surfactants were evaluated for yield and cationic content. The instrumental techniques, viz. FT-IR and 1H-NMR, verified the formation of imidazolines and their subsequent quaternization. The surface-active and performance properties of the cationic imidazolines in terms of critical micelle concentration, surface tension, dispersibility, emulsion stability, softening, rewettability and antistatic properties were also reported. [source] Surfactant-Assisted Preparation of Novel Layered Silver Bromide-Based Inorganic/Organic Nanosheets by Pulsed Laser Ablation in Aqueous Media,ADVANCED FUNCTIONAL MATERIALS, Issue 17 2007C. He Abstract A novel layered AgBr-based inorganic/organic nanocomposite was prepared by pulsed laser ablation (PLA) of Ag in aqueous media in the presence of cetyltrimethylammonium bromide (CTAB), and the formation mechanism of two-dimensional nanosheet was discussed. TEM observations indicate that the obtained AgBr-based inorganic/organic nanocomposite possesses a well-defined two-dimensional shape and that the size of the nanosheet can be changed with the surfactant concentration in the solution. X-ray diffraction (XRD) pattern was composed of a series of peaks that could be indexed to (00l) reflections of a layered structure, and the basal spacing of 20.0,Å indicated that the surfactant was included between the AgBr interlayers in an interdigitated bilayer arrangement. In contrast, a layered inorganic/organic nanocomposite cannot be formed at a CTAB concentration lower than the critical micelle concentration (CMC). Based on our detailed investigation, we proposed the nanocomposite formation process, that is, that negatively charged inorganic AgBr was produced by a strong reaction between the ablated Ag species and the bromide ions, which are concurrently assembling with cationic surfactant molecules controlled by the charge-matching mechanism. [source] Nanoporous Alumina Membranes as Diffusion Controlling SystemsADVANCED FUNCTIONAL MATERIALS, Issue 12 2004S. Kipke Abstract This work describes the use of nanoporous alumina membranes for the diffusion of crystal violet molecules, encapsulated in the micelles of sodium dodecylsulfate (SDS), through pores ranging between 20 and 200,nm in diameter. The encapsulation of the crystal violet in SDS micelles is necessary in order to enlarge the size of the molecules to such an extent that the pore size becomes a speed-controlling function. Superior results were obtained when the membrane-containing capsule is placed into a water-filled beaker, and carefully moved by means of a "tipping bridge" in order to prevent diffusion problems in the capsule. Free crystal violet was liberated following diffusion due to the low SDS concentration in the aqueous solution, which was far below the critical micelle concentration (CMC). Micelle formation and encapsulation of crystal violet is shown by UV-visible and fluorescence spectroscopies. The experiments described herein serve as an exploratory test for developing novel drug delivery systems. [source] Effect of self-assemblies of various surfactants in their single and mixed states on the BZ oscillatory reactionINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 11 2010Muzaffar Hussain Najar Micelles of different surfactants are well known to affect chemical equilibria and reactivities by selectively sequestering the reagent substrates through electrostatic and hydrophobic interactions. In this article, the effects of micelles of various surfactants on different parameters of the Ce(IV)-catalyzed Belousov,Zhabotinsky (BZ) oscillatory reaction at 35°C in nonstirred closed conditions are studied by employing spectrophotometry and tensiometry. Surfactants used in this study are the cationics hexadecyltrimethylammonium bromide (CTAB) and pentamethylene-1,5-bis(N -hexadecyl- N,N -dimethylammonium)bromide gemini (Gemini), anionic sodium dodecylbenzene sulfonate (SDBS), and nonionic Brij58, whereas the binary surfactant systems used are cationic,nonionic CTAB+Brij58 and anionic,nonionic SDBS+Brij58. The results revealed that the induction period shows a definite variation with increasing concentration of different surfactants above their critical micelle concentration (cmc). The amplitudes of oscillation and absorbance maxima and minima are enhanced in the presence of micelles of CTAB and Gemini surfactants, whereas micelles of SDBS and Brij58 have almost no effect on the nature of the oscillations. However, mixed micelles of CTAB+Brij58 and SDBS+Brij58 binary mixtures show a quite different effect on the overall behavior of the oscillations. The enhanced effect of CTAB and Gemini surfactants on the overall nature of oscillations has been attributed to the positive charge on the surface of their micelles and to some extent on the presence of nitrogen in their head group. The effect of mixed binary micelles may be attributed to their synergistic nature. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 659,668, 2010 [source] Kinetics of Fe(II) reduction of cis -halogeno(dodecylamine) bis(ethylenediamine)- cobalt(III) complex ion in aqueous solutionsINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 2 2006K. Santhakumar Kinetics of reduction of the surfactant complex ions, cis -chloro/bromo (dodecylamine)bis(ethylenediamine)cobalt(III) by iron(II) in aqueous solution was studied at 303, 308, and 313 K by spectrophotometry method under pseudo-first-order conditions, using an excess of the reductant. The second-order rate constant remains constant below critical micelle concentration (cmc), but increases with cobalt(III) concentration above cmc, and the presence of aggregation of the complex itself alters the reaction rate. The rate of reaction was not affected by the added [H+]. Variation of ionic strength (,) influences the reaction rate. Activation and thermodynamic parameters have been computed. It is suggested that the reaction of Fe2+ (aq) with cobalt(III) complex proceeds by the inner-sphere mechanism. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 38: 98,105, 2006 [source] Effects of alcohols on micellization and on the reaction methyl 4-nitrobenzenesulfonate + Br, in cetyltrimethylammonium bromide aqueous micellar solutionsINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 12 2004María Muñoz The effects of n -hexanol, n -pentanol, and n -butanol on the critical micelle concentration (cmc), on the micellar ionization degree (,), and on the rate of the reaction methyl 4-nitrobenzenesulfonate + Br, have been investigated in cetyltrimethylammonium bromide (CTAB) aqueous solutions. An increase in the alcohol concentration present in the solution produces a decrease in the cmc and an increase in the micellar ionization degree. Kinetic data show that the observed rate constant decreases as alcohol concentration increases. This result was rationalized by considering variations in the equilibrium binding constant of the methyl 4-nitrobenzenesulfonate molecules to the micelles, variations in the interfacial bromide ion concentration, and variations in the characteristics of the water,alcohol bulk phase provoked by the presence of alcohols. When these operative factors are considered, kinetic data in this and other works show that the second-order rate constants in the micellar pseudophases of water,alcohol micellar solutions are quite similar to those estimated in the absence of alcohols. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 634,641, 2004 [source] Targeted delivery of salicylic acid from acne treatment products into and through skin: role of solution and ingredient properties and relationships to irritationINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 4 2004L. Rhein Salicylic acid (SA) is a beta-hydroxy acid and has multifunctional uses in the treatment of various diseases in skin such as acne, psoriasis, and photoaging. One problem often cited as associated with salicylic acid is that it can be quite irritating at pH 3,4, where it exhibits the highest activity in the treatment of skin diseases. We have identified strategies to control the irritation potential of salicylic acid formulations and have focused on hydroalcoholic solutions used in acne wipes. One strategy is to control the penetration of SA into the skin. Penetration of the drug into various layers of skin, i.e. epidermis, dermis, and receptor fluid, was measured using a modified Franz in vitro diffusion method after various exposure times up to 24 h. A polyurethane polymer (polyolprepolymer-15) was found to be an effective agent in controlling delivery of SA. In a dose-dependent fashion it targeted delivery of more SA to the epidermis as compared to penetration through the skin into the receptor fluid. It also reduced the rapid rate of permeation of a large dose of SA through the skin in the first few hours of exposure. A second strategy that proved successful was incorporation of known mild nonionic surfactants like isoceteth-20. These surfactants cleanse the skin, yet due to their inherent mildness (because of their reduced critical micelle concentration and monomer concentration), keep the barrier intact. Also, they reduce the rate of salicylic acid penetration, presumably through micellar entrapment (either in solution or on the skin surface after the alcohol evaporates). Cumulative irritation studies showed that targeting delivery of SA to the epidermis and reducing the rapid early rate of penetration of large amounts of drug through the skin resulted in a reduced irritation potential. In vivo irritation studies also showed that the surfactant system is the most important factor controlling irritancy. SA delivery is secondary, as formulations with less SA content reduced the rate of delivery to the receptor and yet were some of the most irritating formulations tested, presumably due to the action of the specific anionic surfactant on the barrier. Alcohol content also did not appreciably affect irritation and SA delivery; formulations with considerably low alcohol content but containing anionic versus nonionic surfactant systems exhibited considerably higher irritancy. Thus the surfactant type was again the predominant factor in those studies, although arguably alcohol plays some role (solubilization of SA). Results showed that both polymers and mild surfactants work in concert to provide the optimal formulation benefits of targeted delivery and reduced irritation. Synergistic relationships among hydroalcoholic formulation components will be discussed along with the mechanisms likely involved in controlling delivery of SA to skin. [source] Synthesis of new cationic surfactants based on recycled poly(ethylene terephthalate) for deinking of solvent-based ink from low-density polyethylene surfaceJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2010Samya I. El-Sherbiny Abstract Water-soluble oligomers based on poly-(ethylene terephthalate) waste, PET, were prepared from transesterification of PET with diethanolamine and triethanolamine in the presence of manganese acetate as a catalyst at temperature of 200°C for 8 h. New cationic surfactants were prepared by reaction of the produced recycled oligomers with bromoacetic acid followed by quaternization with pyridine. The chemical structure of the prepared surfactants was confirmed by 1H-NMR analysis. The surface tension, critical micelle concentration, and surface activities were determined at different temperatures. Surface parameters such as surface excess concentration (,max max), the area per molecule at interface (Amin), and the effectiveness of surface tension reduction (,CMC) were determined from the adsorption isotherms of the prepared surfactants. The prepared surfactants were tested as ink removal for printed low-density polyethylene surface. The effect of surfactants concentrations, pH, soaking time, and shaking time were investigated for deinking process. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Effectiveness test of alginate-derived polymeric surfactantsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 2 2002Hyun-Ah Kang Abstract A series of alginate-derived polymeric surfactants (APSs) with a linear alkyl group (C8, C12, C16) was synthesized by oxidation followed by reductive amination of 2,3-dialdehydic alginate. The products were characterized by measuring IR spectra, NMR spectra, surface tension and critical micelle concentration (cmc). They were also tested for the solubilization of azobenzene and adsorption of heavy metal. In the case of 40% CHO-C8 APSs, the lowest interfacial tension value (31.5,m Nm,1) was obtained at the cmc value of 1.35,g,dm,3. The dissolving capacity of 40% CHO-C8 APS towards azobenzene was 27 times greater than that of alginate. The overall cobalt (Co2+) removal efficiency by adsorption using APSs was high compared with that of sodium alginate at pH 3, 5 and 7. Equilibrium aspects of cobalt adsorption onto 10% CHO-APSs were studied, and the results show that APSs had high equilibrium capacities for cobalt uptake, 115.5,mgg,1. © 2002 Society of Chemical Industry [source] Intracellular uptake and trafficking of Pluronic micelles in drug-sensitive and MDR cells: Effect on the intracellular drug localizationJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 1 2002Natalya Rapoport Abstract The intracellular uptake and localization of a fluorescently labeled Pluronic P-105 in HL-60 leukemia cells and in A2780 drug-sensitive and A2780/ADR MDR ovarian carcinoma cells were characterized by flow cytometry and fluorescence microscopy. Pluronic P-105 molecules were labeled with a pH-sensitive fluorescent label, 5-(and 6-)carboxy-2,7,-dichlorofluorescein. The fluorescence intensity of labeled Pluronic was about twofold higher at pH 7.4 than at pH 5.5. At Pluronic concentrations exceeding the critical micelle concentration (cmc), flow cytometry histograms manifested bimodal distribution of cell fluorescence for all types of cells. Cell population characterized by higher fluorescence intensity presumably resulted from Pluronic transfer from the acidic environment of cytoplasmic vesicles (endosomes or lysosomes) into the neutral environment of the cytoplasm and cell nuclei, which suggested the permeabilization of the membranes of acidic vesicle by Pluronic molecules. For the MDR cells, the bimodal distribution of cell fluorescence was already observed at very low Pluronic concentrations in the incubation medium (i.e., below the cmc). The data suggest that the membranes of acidic vesicles of MDR cells are more susceptible to the action of polymeric surfactants than those of drug-sensitive cells. Permeabilization of acidic vesicles had a dramatic effect on the intracellular trafficking of drugs: when delivered in PBS, the anthracyclin drug ruboxyl (Rb) sequestered in cytoplasmic vesicles and was excluded from cell nuclei; however, when delivered in Pluronic micelles, drug accumulated in cell nuclei. Drug uptake from/with Pluronic micelles was substantially enhanced by ultrasound. These findings suggest that the nuclear accumulation of drugs internalized via fluid-phase endocytosis can be enhanced by the application of Pluronic micelles and can be further augmented by ultrasonic irradiation. © 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91:157,170, 2002 [source] The influence of aggregate microenvironment on the dissolution of oxazepam in ternary surfactant interactive mixturesJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 9 2002Peter J. Stewart ABSTRACT The purpose of this research was to test the hypothesis that the dissolution rate of oxazepam in interactive mixtures was dependent on the influence of surfactant within the microenvironment of mixed oxazepam-surfactant aggegrates produced during dissolution. The studies utilised both powder and intrinsic dissolution methodology; spectrophotometric assays were developed and validated and dissolution data were modelled using multi-exponential equations and dissolution rate constants estimated using non-linear least squares algorithms. For a series of water-soluble ternary additives to the oxazepam interactive mixture, sodium lauryl sulfate and cetrimide were shown not only to decrease aggregation through enhanced dispersion, but also to increase the dissolution rate constant. Such an increase in dissolution rate constant was observed in the intrinsic dissolution studies when surfactant concentrations exceeded the critical micelle concentration and the oxazepam solubility increased. Laser diffraction particle sizing during the dissolution process confirmed the presence of dispersed particles and aggregates and demonstrated that the presence of surfactant improved the state of dispersion. The results of studies using different rotational speeds produced unexpected increases in aggregation and decreases in dissolution rate constants at about 150 rev min,1, consistent with the transient formation of loose aggregates containing dissolved surfactant. [source] A gemini amphiphilic phase transfer catalyst for dark singlet oxygenationJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 7-8 2008Cédric Borde Abstract A new gemini surfactant phase transfer catalyst, namely diethyl-ether-,,,-bis-(dimethyldodecylammonium molybdate) codified as 12-EO-12-Mo, was prepared by anion exchange from the analogous gemini dichloride (12-EO-12-Cl2). The physico-chemical properties of these compounds such as Krafft temperature, critical micelle concentration, surface activity and binary water-surfactant behavior were compared and the influence of the molybdate counterion was examined. Though both compounds are highly hydrophilic, the cmc of 12-EO-12-Mo (0.4,mmol L,1) is about five times lower than of its dichloride analogue (2.2,mmol L,1). Moreover, 12-EO-12-Mo exhibits an additional cubic liquid crystal phase between 53 and 64,wt%. The usefulness of 12-EO-12-Mo as an amphiphilic phase transfer catalyst for the dark singlet oxygenation was demonstrated with the peroxidation of two typical organic substrates: ,-terpinene which reacts with 1O2 according to a [4,+,2] cycloaddition and the less reactive ,-citronellol, which provides two hydroperoxides according to the ene-reaction. 12-EO-12-Mo provides a simple reaction medium with only three components for the preparative peroxidation of hydrophobic substrates by chemically generated singlet oxygen. Copyright © 2008 John Wiley & Sons, Ltd. [source] Multistimuli responsive micelles based on well-defined amphiphilic comb poly(ether amine) (acPEA)JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 15 2010Chunfeng Di Abstract A series of well-defined amphiphilic comb poly (ether amine)s (acPEAs) were successfully synthesized through nucleophilic addition/ring-opening reaction of commercial available poly(propylene glycol) (PPO) diglycidyl ether and Jeffamine L100, followed by esterification of hydroxyl groups in backbone by alkyl carboxylic acid with different chain length. acPEAs are comprised of hydrophilic short PEO chains and hydrophobic alkyl chains as comb chains, which are grafted on PPO backbone alternately to form well-defined structure. With the very low critical micelle concentration (CMC) of around 3.0 × 10,3 g/L, the obtained acPEAs can self-assemble into stable nanomicelles, whose aggregation is responsive to temperature, pH, and ionic strength with tunable cloud point (CP). The CP of acPEAs' aqueous solution increases with the decrease of the length of graft alkyl chains, the decrease of pH value, and the decrease of ionic strength. A transition behavior in the responsive aggregation of micelles formed by acPEA8 and acPEA10 in aqueous solution, especially at low pH value (<7.0), was observed, which was also revealed by DLS results. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3468,3475, 2010 [source] Synthesis of phenanthroline-terminated polymers and their Fe(II)-complexesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 12 2010Miklós Nagy Abstract Well-defined mono- and bifunctional, phenanthroline-terminated poly(ethylene glycol) and polyisobutylene capable of polymer network formation were synthesized. The starting materials mono- and bi-phenanthroline- (phen) terminated poly(ethylene glycols) (mPEG-phen, phen-PEG-phen) and polyisobutylenes (PIB-phen, phen-PIB-phen) were prepared by the Williamson synthesis and characterized by means of 1H NMR and MALDI-TOF mass spectrometry. According to UV,Vis spectrophotometry and ESI-TOF mass spectrometry, the phenanthroline-terminated polymers underwent quantitative complex formation with ferrous ions in solution. The aqueous solution of mPEG-phen shows self-assembly behavior. Important parameters, such as critical micelle concentration and hydrodynamic radius of the aggregates were also determined. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2709,2715, 2010 [source] Developing a hybrid emulsion polymerization system to synthesize Fe3O4/polystyrene latexes with narrow size distribution and high magnetite contentJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2007Longlan Cui Abstract A hybrid emulsion polymerization was formulated for synthesizing Fe3O4/polystyrene composite latex. This system, containing binary droplets that are magnetic (Mag)-droplets with a diameter of 100,200 nm and styrene (St)-droplets with a diameter of 3,4 ,m, was obtained by mixing Mag-miniemulsion and St-macroemulsion. With extremely low surfactants concentration (,critical micelle concentration, CMC), the nucleated loci are selectively controlled in the Mag-droplets, as the result of smaller droplet size and larger surface ratio. Both water-soluble potassium persulfate (KPS) and oil-soluble 2,2,-azobis(2-isobutyronitrile) was adopted to initiate the polymerization. In the presence of KPS, magnetic polystyrene latices with particles size of 60,200 nm, narrow size distribution, and high magnetite content (86 wt % measured by TGA) were attained successfully. The synthesized magnetic Fe3O4/polystyrene latices assembled into well-ordered hexagonal structure in the surface of a carbon supported copper grid. The influence of various parameters on various aspects of the as-synthesized Fe3O4/polystyrene was investigated in detail: type of initiator on composite morphology, feed ratio of Mag-miniemulsion and St-macroemulsion on magnetite content, and hydrophobic agent or amount of surfactant on size and size distribution. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5285,5295, 2007 [source] Synthesis and interfacial behaviors of amphiphilic poly(oxypropylene) amidoacidsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2006Kuan-Liang Wei Abstract A series of hydrophobic poly(oxypropylene) (POP)-backboned and hydrophilic poly(oxyethylene)-backboned amidoacids and imidoacids were prepared through the reaction of poly(oxyalkylene) diamines and trimellitic anhydride (TMA) under mild conditions. The synthesized copolymers were characterized with nuclear magnetic resonance and Fourier transform infrared. Their ability to lower the water surface tension and toluene/water interfacial tension was measured and correlated with the hydrophobic/hydrophilic balance with multiple sodium carboxylate functionalities. The specific POP2000/TMA copolymers, consisting of a 2000 g/mol POP segment and multiple amidoacid functionalities, enabled the demonstration of a strong surfactant tendency and a critical micelle concentration at 0.1 wt %. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 646,652, 2006 [source] Kinetics of styrene emulsion polymerization above the critical micelle concentration: Effect of the initial monomer concentration on the molecular weightJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 9 2005Jorge Herrera-Ordonez Abstract The emulsion polymerization of styrene above the critical micelle concentration has been experimentally studied from a low final polymer content up to a high polymer content (,50%). A maximum in the molecular weight (M) evolution has been observed in all cases. The presence or absence of such a maximum depends on the relative values of the rate of free-radical entry (,) and the rate of chain transfer to the monomer (KtrCMp, where Ktr is the chain transfer to monomer rate coefficient and CMp is the monomer concentration in particles). If , , KtrCMp, M is constant and equal to Kp/Ktr (where Kp is the propagation rate coefficient), except at very low particles sizes typical of the early stages of the reaction, in which the chain length is limited by the particle size. On the other hand, if , , KtrCMp, M is determined by both CMp and ,. It is proposed that , is determined by the sum of the entry of the oligomeric radicals formed in the aqueous phase and those contained in particles that undergo limited coagulation. This coagulative entry can become very significant; therefore, reactor hydrodynamics can play a major role in the kinetic behavior observed. Disagreement between Clay and Gilbert's model and molecular weight distribution data can be ascribed, to a lesser or greater extent, to the degree of correctness of the quasi-steady-state and instantaneous-termination approaches. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1963,1972, 2005 [source] Synthesis and hydrogel formation of fluorine-containing amphiphilic ABA triblock copolymersJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2001Kozo Matsumoto Abstract Fluorine-containing amphiphilic ABA triblock copolymers, poly(2-hydroxyethyl vinyl ether)- block -poly[2-(2,2,3,3,3-pentafluoropropoxy)ethyl vinyl ether]- block -poly(2-hydroxyethyl vinyl ether) [poly(HOVE- b -PFPOVE- b -HOVE)] (HFH), poly[2-(2,2,3,3,3-pentafluoropropoxy)ethyl vinyl ether]- block -poly(2-hydroxyethyl vinyl ether)- block -poly[2-(2,2,3,3,3-pentafluoropropoxy)ethyl vinyl ether] [poly(PFPOVE- b -HOVE- b -PFPOVE)] (FHF), and poly(n -butyl vinyl ether)- block -poly(2-hydroxyethyl vinyl ether)- block -poly(n -butyl vinyl ether) [poly(NBVE- b -HOVE- b -NBVE)] (LHL), were synthesized, and their behavior in water was investigated. The aforementioned polymers were prepared by sequential living cationic polymerization of 2-acetoxyethyl vinyl ether (AcOVE) and PFPOVE or NBVE, followed by hydrolysis of acetyl groups in polyAcOVE. FHF and LHL formed a hydrogel in water, whereas HFH gave a homogeneous aqueous solution. In addition, the gel-forming concentration of FHF was much lower than that of corresponding LHL. Surface-tension measurements of the aqueous polymer solutions revealed that all the triblock copolymers synthesized formed micelles or aggregates above about 1.0 × 10,4 mol/L. The surface tensions of HFH and FHF solutions above the critical micelle concentration were lower than those of LHL, indicating high surface activity of fluorine-containing triblock copolymers. Small-angle X-ray scattering measurements revealed that HFH formed a core-shell sperical micelle in 1 wt % aqueous solutions, whereas the other block copolymers caused more conplicated assembly in the solutions. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3751,3760, 2001 [source] Surfactant characteristics of polystyrene/poly(ethylene oxide) macromonomers in aqueous solution and on polystyrene latex particles: Two-step emulsion polymerizationsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2001Sebastien Gibanel Abstract Macromonomers were synthesized by anionic "living" polymerization. They comprised a poly(ethylene oxide) hydrophilic block and a hydrophobic block or sequence terminated with an unsaturation. The surface activity properties of these materials (critical micelle concentration and parking area) were determined, and the values were compared and discussed in terms of the molecular structure of these new surfactants. Some of the macromonomers were employed as emulsifiers in two-step emulsion polymerizations. The data obtained were discussed while taking into account the different chemical structures of the macromonomers and the efficiency of these species as emulsifiers in the polymerization recipes. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2767,2776, 2001 [source] Methyl methacrylate emulsion polymerization at low monomer concentration: Kinetic modeling of nucleation, particle size distribution, and rate of polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 14 2001Jorge Herrera-Ordóñez Abstract The results of a mathematical model developed in the authors' previous work are discussed and compared against final number (N) and size distribution of particles (PSD) and the rate of polymerization (RP) experimental data of methyl methacrylate (MMA) emulsion polymerization above the critical micelle concentration (cmc) of the surfactant. On the basis of the model results, the hypothesis that the observed bimodal PSD can be ascribed to secondary nucleation as proposed in the literature is questionable. It is discussed that this PSD can also be caused by differences in the growing rate of different-size particles as predicted for styrene emulsion polymerization. Because of the small particle size obtained at low initial monomer concentration, the high rate of free-radical desorption reduces the accumulation of these species; therefore, the autoacceleration effect is less pronounced for the conditions under study compared with the usual behavior of the RP during MMA emulsion polymerization above cmc. Similarities and differences between model predictions and experimental data are discussed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2547,2556, 2001 [source] Characterization of glycolipid biosurfactant from Pseudomonas aeruginosa CPCL isolated from petroleum-contaminated soilLETTERS IN APPLIED MICROBIOLOGY, Issue 1 2010J. Arutchelvi Abstract Aims:, To isolate and characterize the biosurfactant-producing micro-organism from petroleum-contaminated soil as well as to determine the biochemical properties of the biosurfactant. Methods and Results:, A novel rhamnolipid-producing Pseudomonas aeruginosa (GenBank accession number GQ241355) strain was isolated from a petroleum-contaminated soil. Surface active compound was separated by solvent extraction of the acidified culture supernatant. The extract was able to reduce the surface tension of water from 72 to 44 mN m,1 at a critical micelle concentration of 11·27 ± 1·85 mg l,1. It showed better activity (based on microdilution method) against Gram-positive (, 31 mg ml,1) bacteria and filamentous fungi (, 50 mg ml,1) than Gram-negative bacteria (, 125 mg ml,1) with mild toxicity (HC50, 38 ± 8·22 ,g ml,1) to red blood cells. Fourier transform infrared spectroscopy revealed the presence of aliphatic chain, hydroxyl groups, ester and glycosidic bonds. Presence of nineteen rhamnolipid homologues with variation in chain length and saturation was revealed from liquid chromatography coupled to mass spectrometry with electrospray ionization. Conclusion:, The results indicate that the isolated biosurfactant has a novel combination of rhamnolipid congeners with unique properties. Significance and Impact of the Study:, This study provides a biosurfactant, which can be used as a biocontrol agent against phytopathogens (Fusarium proliferatum NCIM 1105 and Aspergillus niger NCIM 596) and exploited for biomedical applications. [source] Reduction-Sensitive Reversibly Crosslinked Biodegradable Micelles for Triggered Release of DoxorubicinMACROMOLECULAR BIOSCIENCE, Issue 12 2009Yanmin Xu Abstract Reduction-responsive reversibly crosslinked biodegradable micelles were developed and applied for triggered release of doxorubicin (DOX). An amphiphilic block copolymer of poly(ethylene glycol) (PEG) and poly(, -caprolactone) (PCL) that contains two lipoyl functional groups at their interface (PEG-L2 -PCL) has been synthesized. 1H NMR spectroscopy and gel permeation chromatography (GPC) measurements show that the PEG-L2 -PCL block copolymer had a controlled composition (PEG 5 kDa and PCL 5.4 kDa) and a polydispersity index (PDI) of 1.36. PEG-L2 -PCL formed micelles with sizes that ranged from 20 to 150,nm in aqueous solutions, wherein a critical micelle concentration (CMC) of 16,mg·L,1 was determined. The micelles were readily crosslinked by adding 7.6,mol % of dithiothreitol (DTT) relative to the lipoyl groups. Notably, micelles after crosslinking demonstrated a markedly enhanced stability against dilution, physiological salt concentration, and organic solvent. In the presence of 10,×,10,3,M DTT, however, micelles were subject to rapid de-crosslinking. In vitro release studies showed minimal release of DOX from crosslinked micelles at a concentration of 10,mg,L,1 (C,<,CMC, analogous to intravenous injection), wherein less than 15% of the DOX was released in 10,h. In contrast, rapid release of DOX was observed for DOX-loaded non-crosslinked micelles under otherwise the same conditions (,80% release in 0.5,h). In the presence of 10,×,10,3,M DTT mimicking an intracellular reductive environment, sustained release of DOX from crosslinked micelles was achieved, in which 75% of the DOX was released in 9,h. These novel reduction-sensitive reversibly crosslinked biodegradable micelles are highly promising for targeted intracellular delivery of anticancer drugs. [source] Surfactant-Induced Amorphous Aggregation of Tobacco Mosaic Virus Coat Protein: A Physical Methods ApproachMACROMOLECULAR BIOSCIENCE, Issue 2 2008Yuliy V. Panyukov Abstract The interactions of non-ionic surfactant Triton X-100 and the coat protein of tobacco mosaic virus, which is an established model for both ordered and non-ordered protein aggregation, were studied using turbidimetry, differential scanning calorimetry, isothermal titration calorimetry, and dynamic light scattering. It was found that at the critical aggregation concentration (equal to critical micelle concentration) of 138,×,10,6M, Triton X-100 induces partial denaturation of tobacco mosaic virus coat protein molecules followed by protein amorphous aggregation. Protein aggregation has profound ionic strength dependence and proceeds due to hydrophobic sticking of surfactant-protein complexes (start aggregates) with initial radii of 46 nm. It has been suggested that the anionic surfactant sodium dodecyl sulfate forms mixed micelles with Triton X-100 and therefore reverses protein amorphous aggregation with release of protein molecules from the amorphous aggregates. A stoichiometric ratio of 5 was found for Triton X-100-sodium dodecyl sulfate interactions. [source] Synthesis and morphology transformation of amphiphilic diblock polyurethane copolymers in aqueous solutionPOLYMER INTERNATIONAL, Issue 8 2010Qing Miao Abstract Amphiphilic block copolymers possess both hydrophobic and hydrophilic properties and can form versatile micellar structures in aqueous solution. The aim of the research presented was to prepare a series of non-ionic amphiphilic diblock polyurethane copolymers (PUn) based on isophorone diisocyanate, monoallyl-end-capped poly(ethylene oxide) and poly(propylene oxide) (PPO), followed by an investigation of their micellization properties and morphology transformation in aqueous solution. The PUn samples were synthesized by condensation polymerization. These polyurethanes exhibit surface tension as low as 33.7,37.0 mN m,1. There is an obvious decrease in critical micelle concentration as the hydrophobic PPO molecular weight increases. According to transmission electron microscopy, the morphology of aggregates of the copolymers can be tuned by varying the concentration in aqueous solution rather than organic solvent. For example, for PU7, large compound micelles are produced instead of vesicles. For PU17, the concentration can be used to control the size and thickness of vesicles. Vesicle size increases from 60 to 500 nm and vesicle thickness from 40 to 60 nm with concentration ranging from 0.003 to 0.03 wt%. The study shows that the copolymers in aqueous solution have excellent surface activities. In addition, they can self-assemble into large compound micelles or vesicles at certain concentrations. Moreover, the synthesis method described allows one to obtain a desired morphology of aggregates by adjusting the composition of hydrophilic and hydrophobic segments, which provides a novel and simple way to obtain particles on the nanometer scale. Copyright © 2010 Society of Chemical Industry [source] Surface activity,thermodynamic properties and light scattering studies for some novel aliphatic polyester surfactantsPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 5 2004R. A. El-Ghazawy Abstract The preparation of 12 new polyester surfactants based on aliphatic amines and different ethylene oxide content is described. These surfactants were characterized by determining their molecular weights and polydispersity by gel permeation chromatography (GPC) and nitrogen content. Drop volume tensiometry (DVT) was used to measure the surface tension at 25, 35, 45 and 55°C. The surface tension isotherms were used to determine critical micelle concentration (CMC), maximum Gibb's adsorption (,max), minimum area per molecule (Amin), the effectiveness of surface tension reduction (,cmc) and the efficiency (pC20). The thermodynamic parameters of micellization (,Gmic, ,Hmic, ,Smic) and of adsorption (,Gad, ,Had, ,Sad) were calculated and the data showed that these surfactants favor micellization to adsorption. The static scattered light intensity measurements provide the calculation of the molecular weight of micelle and the aggregation number (N°), while the dynamic light scattering provide the hydrodynamic radius of micelle (RH) and the diffusion coefficient at different surfactant concentrations. The hydrodynamic radius of micelle (RH) at different surfactant concentrations could be used also to determine the CMC giving results that are comparable to those obtained by surface tension measurements. All the data are discussed regarding the chemical structure of the polymeric surfactants. Copyright © 2004 John Wiley & Sons, Ltd. [source] Factors affecting the adsorption of ethoxylated nonyl phenol onto synthetic rubberPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 1 2003A. A. El-Feky Abstract Adsorption of non-ionic surfactant (ethoxylated nonyl phenol; ENP) from aqueous solution is studied at 30,°C using butyl rubber (II R) mixed with two types of carbon black: high abrasion furnace (HAF) and general purpose furnace (GPF) as fillers with different concentrations. The results indicate that butyl loaded with HAF is more efficient as adsorbent surface than that loaded with GPF irrespective of the carbon black concentration and the adsorption increases as the immersion time increases. The experimental data of adsorption isotherms could be fitted to the Langmuir equation below the critical micelle concentration (CMC) of ENP. Copyright © 2003 John Wiley & Sons, Ltd. 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