Phase Behavior of a Mixture of Poly(isoprene)−Poly(oxyethylene) Diblock Copolymer and Poly(oxyethylene) Surfactant in Water

Kunieda, H.; Kaneko, Masaya; López‐Quintela, M. Arturo; Tsukahara, Masahiko

doi:10.1021/la035562l

Cited by 28 publications

(25 citation statements)

References 23 publications

(32 reference statements)

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“…The former result is similar to literature findings for C 12 E 5 micelles containing dodecane 19 and PI-PEO. 22 As pointed out by Menge et al, the decrease of R H along with M w is considered due to a transition from wormlike micelles to microemulsion droplets. The incorporation of ndodecane into the cylindrical micelles may cause increase of micellar diameter and then decrease in hydrophilic interaction among polyoxyethylene tails of C 12 E 6 molecules and solvent water, resulting in decrease of solubility of the micelles.…”

Section: Dynamic Light Scatteringmentioning

confidence: 99%

“…Kunieda et al 21,22 studied the size evolution of the C 12 E 5 , C 12 E 6 , C 12 E 7 , and C 12 E 9 micelles with addition of poly(isoprene)-poly(oxyethylene) diblock copolymer (PI-PEO or C 250 E 70 ) by DLS measurements. Their results reveal that the (apparent) hydrodynamic radius R H,app of the C 12 E 5 micelles becomes smaller at low PI-PEO content up to weight fraction of 0.2, passes through a minimum, and then increases with increasing PI-PEO content.…”

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confidence: 99%

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Variation in Size and Shape of Hexaoxyethylene Dodecyl Ether C12E6 Micelles with Uptake of n-Dodecane and n-Dodecanol in Dilute Aqueous Solution

Einaga

Totake

Matsuyama

2004

Polym J

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ABSTRACT:The size and shape of hexaoxyethylene dodecyl ether C 12 E 6 micelles in dilute aqueous solutions with oil (n-dodecane and n-dodecanol) uptake were investigated by static (SLS) and dynamic light scattering (DLS) experiments at 40.0 C for the C 12 E 6 + water + n-dodecane system and at 25.0 C for the C 12 E 6 + water + n-dodecanol system. The micelles collapse into the smaller ones by incorporating n-dodecane, implying that the incorporation of the oil weakens hydrophilic interactions among polyoxyethylene tail of the surfactant molecules and water too significantly to maintain the original micellar size. The inclusion of n-dodecanol causes growth in the micellar size, suggesting that n-dodecanol plays a role as a kind of co-surfactant. Accompanying size change, the micelles were found to alter their shape from the original wormlike shape to prolate ellipsoid with the oil uptake. The axial ratios determined are 17.4 and 9.2 for micelles containing n-dodecane and n-dodecanol, respectively. Non-ionic surfactant polyoxyethylene alkyl ether C i E j forms polymer-like or wormlike micelles in dilute aqueous solutions (L 1 phase). [1][2][3][4][5][6][7][8][9][10][11][12][13][14] Here, i and j are the numbers of methylene and oxyethylene groups, respectively. The micelles grow in size with increasing surfactant concentration and raising temperature toward the lower consolute phase boundary. In the preceding paper, 15 we determined shape, size, and weight-average molar mass M w of the C 12 E 6 and C 14 E 6 micelles by static (SLS) and dynamic light scattering (DLS). The characterization of individual ''isolated''micelles of C 12 E 6 and C 14 E 6 free from intermicellar interactions at finite surfactant concentrations was done with the aid of the thermodynamic theory for SLS of micellar solutions. 16 Extrapolations of the SLS and DLS results to infinite dilution yield the data set representing the relationships between the hydrodynamic radius R H and M w for the isolated micelles in dilute solutions.The size and shape of the C i E j micelles vary with uptake of oils into the cylindrical micelles. Menge et al. [17][18][19] investigated the effects of added oil on the structure of the micelles in the L 1 phase of the system C 12 E 5 + water + decane by SLS, DLS, and smallangle neutron scattering (SANS) measurements. They showed that at overall concentrations of C 12 E 5 + decane up to ca. 0.100 g/cm 3 , the (apparent) molar mass of the micelles gradually increases with decane content up to the decane mass fraction of ca. 0.07-0.10, and then sharply decreases with further increase of decane content. The micelles at low decane and C 12 E 5 + decane concentrations may be represented with a wormlike polymer model, but at high decane contents, the micelles eventually become microemulsion droplets whose shapes are not necessarily spherical. Variation in micellar shape with oil uptake has been also observed directly by cryogenic temperature transmission electron microscopy (cryo-TEM) for the system C 12 E 5 + water + n-octa...

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Section: Dynamic Light Scatteringmentioning

confidence: 99%

mentioning

confidence: 99%

Variation in Size and Shape of Hexaoxyethylene Dodecyl Ether C12E6 Micelles with Uptake of n-Dodecane and n-Dodecanol in Dilute Aqueous Solution

Einaga

Totake

Matsuyama

2004

Polym J

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“…Phase behavior and self-assembled structures of a variety of surfactants including conventional poly(oxyethylene)-type nonionic surfactants in aqueous systems were extensively studied in the past [9][10][11][12][13] . It has been found that the self-assembled structures of surfactants are influenced by the composition, temperature, and poly(oxyethylene) chain length.…”

Section: Introductionmentioning

confidence: 99%

Structural Investigation of Diglycerol Monolaurate Reverse Micelles in Nonpolar Oils Cyclohexane and Octane

Shrestha

Aramaki

2009

J. Oleo Sci.

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Structure of diglycerol monolaurate (abbreviated as C 12 G 2 ) micelles in nonpolar oils cyclohexane and n-octane as a function of compositions, temperatures, and surfactant chain length has been investigated by small-angle X-ray scattering (SAXS). The SAXS data were evaluated by the generalized indirect Fourier transformation (GIFT) method and real-space structural information of particles was achieved. Conventional poly(oxyethylene) type nonionic surfactants do not form reverse micelles in oils unless a trace water is added. However, present surfactant C 12 G 2 formed reverse micelle (RM) in cyclohexane and n-octane without addition of water at normal room temperature. A clear signature of one dimensional (1-D) micellar growth was found with increasing C 12 G 2 concentration. On the other hand, increasing temperature or hydrocarbon chain length of surfactant shorten the length of RM, which is essentially a cylinder-to-sphere type transition in the aggregate structure. Drastic changes in the structure of RM, namely, transition of ellipsoidal prolate to long rod-like micelles was observed upon changing oil from cyclohexane to octane. All the microstructural transitions were explained in terms of critical packing parameter.

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“…For instance, this quantity for Rz(EO) 15 is equal to 0.002% wt. Increase of the ethoxylation degree causes decrease of micellesÕ size [17].…”

Section: Micellar Solutions and Lyotropic Liquid Crystalsmentioning

confidence: 99%

The effect of ethoxylated esters on the lubricating properties of their aqueous solutions

Sułek

Bocho-Janiszewska

2006

Tribol Lett

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In many applications strict ecological criteria are crucial. Water is often used in these cases as a lubricant base. Its disadvantageous properties, in particular lubricity, can be modified by introduction of additives. Ethoxylated methyl esters of fatty acids from rapeseed oil were chosen for that purpose. In order to verify tribological properties of aqueous solutions of these compounds, anti-seizure properties under linearly increasing load, friction and wear under 2 kN (four-ball machine) were assessed. Not only radical change of tribological properties as compared to water was observed, but also the results are comparable to the ones obtained for mineral oils, which contained typical, commercial additives. Significant changes in scuffing load (P t ), seizure load (P oz ), limiting pressure of seizure (p oz ) were recorded even at 0.1% wt concentration of the additive. At optimal concentration P t , P oz , p oz , increased even almost 6-, 2-and 3-fold (respectively). The quantities measured increased with ethoxylation degree. Also at constant load, friction (6-fold) and wear (almost 2-fold) were reduced. In this case, however, no influence of concentration and ethoxylation degree on the quantities measured, was observed.The tribological properties can be discussed in terms of results of physical-chemical tests. Ethoxylates are surface active compounds. Within the range of concentrations analyzed, they form micelles in a bulk phase and liquid-crystalline structures in a surface phase. High surface activity of these additives and creation of specific structures in solutions were proved by measuring surface tension, wetting angle and mesophases observation in polarized light. On the basis of the results of the physical-chemical and tribological tests one can conjecture that profitable tribological properties of the lubricating compositions are the result of strong affinity to the surface and their ability to form ordered structures. One can expect that over the cooperating surfaces a deposit is formed. Presence of the deposit increases real contact area and prevents seizure. This hypothesis gives a simple explanation of the unexpected improvement of anti-seizure properties, which accompanies the increase of ethoxylation degree. Ethoxylates with higher number of ethylene oxide attached, reveal smaller surface activity and better solubility in water. On the other hand, they can be characterized by higher dehydratation temperature. This means that at higher temperatures they reveal surface activity. That is why, during seizure tests, at high temperature, under high loads the esters of higher ethoxylation degree protect friction couples against seizure much more efficiently.

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Phase Behavior of a Mixture of Poly(isoprene)−Poly(oxyethylene) Diblock Copolymer and Poly(oxyethylene) Surfactant in Water

Cited by 28 publications

References 23 publications

Variation in Size and Shape of Hexaoxyethylene Dodecyl Ether C12E6 Micelles with Uptake of n-Dodecane and n-Dodecanol in Dilute Aqueous Solution

Variation in Size and Shape of Hexaoxyethylene Dodecyl Ether C12E6 Micelles with Uptake of n-Dodecane and n-Dodecanol in Dilute Aqueous Solution

Structural Investigation of Diglycerol Monolaurate Reverse Micelles in Nonpolar Oils Cyclohexane and Octane

The effect of ethoxylated esters on the lubricating properties of their aqueous solutions

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