Effect of interfacial tension on micellization of a polystyrene–poly(ethylene oxide) diblock copolymer in a mixed solvent system

Seo, Youngkyun; Kim, Mahn-Won; Ou-Yang, D.; Peiffer, D. G.

doi:10.1016/s0032-3861(02)00347-6

Cited by 26 publications

(33 citation statements)

References 28 publications

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“…The average value of these angles was used in the interfacial tension calculations. The interfacial tension (γ) between PB and the H 2 O/THF mixtures was calculated from the measured contact angles according to Young's equation 19 …”

Section: Methodsmentioning

confidence: 99%

Structural changes in block copolymer micelles induced by cosolvent mixtures

Kelley¹,

Smart²,

Jackson³

et al. 2011

Soft Matter

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We investigated the influence of tetrahydrofuran (THF) addition on the structure of poly(1,2-butadiene-b-ethylene oxide) [PB-PEO] micelles in aqueous solution. Our studies showed that while the micelles remained starlike, the micelle core-corona interfacial tension and micelle size decreased upon THF addition. The detailed effects of the reduction in interfacial tension were probed using contrast variations in small angle neutron scattering (SANS) experiments. At low THF contents (high interfacial tensions), the SANS data were fit to a micelle form factor that incorporated a radial density distribution of corona chains to account for the starlike micelle profile. However, at higher THF contents (low interfacial tensions), the presence of free chains in solution affected the scattering at high q and required the implementation of a linear combination of micelle and Gaussian coil form factors. These SANS data fits indicated that the reduction in interfacial tension led to broadening of the core-corona interface, which increased the PB chain solvent accessibility at intermediate THF solvent fractions. We also noted that the micelle cores swelled with increasing THF addition, suggesting that previous assumptions of the micelle core solvent content in cosolvent mixtures may not be accurate. Control over the size, corona thickness, and extent of solvent accessible PB in these micelles can be a powerful tool in the development of targeting delivery vehicles.

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Section: Methodsmentioning

confidence: 99%

Structural changes in block copolymer micelles induced by cosolvent mixtures

Kelley¹,

Smart²,

Jackson³

et al. 2011

Soft Matter

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“…As toluene content (water to TTOL) increased, the aggregation number increased in both A (189→285→349) and B (529→765→842) copolymers at The micellization process of block copolymers is analyzed by total free energy calculation. 5 Free energy per copolymer chain of a micelle, F Tot is divided by three parts.…”

Section: Resultsmentioning

confidence: 99%

“…Previously we reported that spherical PS-b-PEO micelle formed in water decreases in aggregation number as THF volume fraction increases from 3 to 20 wt% mainly due to reduction of interfacial tension between PS core and the mixed solvent. 5 The effect of interfacial tension was more distinctly proved later using poly(ethylene-co-propylene)-b-poly(ethylene oxide) (PEP-b-PEO) micelle solubilized in N N -dimethylformamide (DMF)-water mixed solvent 6 where the interface would be sharp in the wide range of DMF volume fraction because the PEP core do not absorb DMF. More recently similar behavior has been also found in the case of triblock copolymer of PS-b-PEO-b-PS dissolved in THF by adding water.…”

Section: Introductionmentioning

confidence: 99%

Effects of Second Solvents on the Interaction of Polymeric Micelles in Aqueous Solution

Seo¹,

Kim²,

Ou-Yang³

2013

Journal of Chemical and Biological Interfaces

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PS-PEO diblock copolymers form micelles in an aqueous solution. The properties of the micellar solution such as aggregation number and second virial coefficient can be markedly changed due to the solubilization of a second solvent. Second solvent means, in this context, a solvent compatible with the core block copolymer. Tetrahydrofuran (THF) and toluene were chosen as the second solvent since toluene and THF are good solvents for both PS and PEO. However, THF is miscible with water, while toluene is only sparingly soluble. Laser light scattering measurement was used to study and compare the effects of these two second solvents on the formation of micelles. Furthermore, two kinds of copolymer, which have different block lengths of PS but the same total molecular weight of the diblock copolymers, are also studied. In all instances, only a slight amount of a second solvent was added. Our results show that the degree of aggregation, micelle interaction strength, and structure are strongly dependent on both the concentration and type of the second solvent. The primary reason is due to absorption of second solvent into the core.

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“…[18][19][20][21][22][23][24][25][26] Bhargava et al [18] observed the evolution of the morphologies for PS-b-PEO micelles by adding water or acetonitrile into the polymer solutions, that is, the morphologies of the micelles change from pure spheres, the mixed spheres and rods, the mixed spheres and long rods, the pure wormlike, the mixed wormlike and vesicles, and finally to the pure vesicles morphologies with the increase of the weight fraction of the added solvents. Logan et al [23] studied the micellization behavior of the PS-b-PEO three-arm star block copolymer at the air=water interface.…”

Section: Introductionmentioning

confidence: 99%

“…Logan et al [23] studied the micellization behavior of the PS-b-PEO three-arm star block copolymer at the air=water interface. Seo et al [26] reported the effect of the interface tension on the micellization of PS-b-PEO block copolymer in THF=water mixing solvent. For the PS-b-PEO-b-PS triblock copolymer, a few attentions have been taken to its micellization behavior by Chen et al [27][28][29][30] In their work, the micellization of the PS 4 -b-PEO 227 -b-PS 4 was carried out by dissolving it in water directly; while the PS 43 -b-PEO 45 -b-PS 43 and PS 18 -b-PEO 18 -b-PS 18 copolymers were dissolved in common solvent and then water was added into the solution to induce the micellization of the copolymer.…”

Section: Introductionmentioning

confidence: 99%

Aggregate Morphologies of PS-b-PEO-b-PS Copolymer in Mixed Solvents

Luo

Han

Gao

et al. 2011

Journal of Dispersion Science and Technology

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Taking the aggregate structures of polystyrene-b-poly (ethylene oxide)-b-polystyrene (PS-b-PEO-b-PS) block copolymer in tetrahydrofuran (THF) and N,N-Dimethylformamide (DMF) solvents as the starting point, further experiments were carried out to change the aggregate morphologies by adding PEO selective solvent, water, into the primarily solutions. Primarily, the microcrystal ''platelets'' and ''spherical'' aggregates were obtained in THF and DMF, respectively. After water being added into the aggregated system in THF, the macrophase separation occurred in the solution, and the further adding of water led to the formation of large compound micelles (LCMs). Nevertheless, the adding of water into spherical aggregates in DMF only leaded the decrease of aggregate size.

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Effect of interfacial tension on micellization of a polystyrene–poly(ethylene oxide) diblock copolymer in a mixed solvent system

Cited by 26 publications

References 28 publications

Structural changes in block copolymer micelles induced by cosolvent mixtures

Structural changes in block copolymer micelles induced by cosolvent mixtures

Effects of Second Solvents on the Interaction of Polymeric Micelles in Aqueous Solution

Aggregate Morphologies of PS-b-PEO-b-PS Copolymer in Mixed Solvents

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