Theory of micelle formation in block copolymer-homopolymer blends

Whitmore, M. D.; Noolandi, Jaan

doi:10.1021/ma00146a014

Cited by 196 publications

(170 citation statements)

References 6 publications

(33 reference statements)

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“…Dilute solutions contain isolated micelles; but by increasing the concentration, some chains may bridge from one micelle to another, thus providing the possibility of building a network that can include the whole solution. It is important to note that this mechanism of micelle formation is quite similar to the one of block copolymers, and therefore, very similar micelle structures can appear (46,47).…”

Section: Discussionmentioning

confidence: 85%

Temporary networks in polymer‐modified asphalts

Polacco

Stastna

Vlachovicova

et al. 2004

Polymer Engineering & Sci

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The viscosity functions of several polymer-modified asphalts (PMAs) were studied at different temperatures in steady-state rate sweep tests. The materials were obtained by mixing different base asphalts with either styrene-butadiene-styrene (SBS), ethylenevinylacetate (EVA) or reactive ethylene terpolymers (RET). The first two polymers form a physical network that is swollen by the asphalt, while the latter is functionalized with glycidylmethacrylate (GMA) and can crosslink and/or chemically bond with the molecules of asphaltenes. In the presence of SBS or EVA, at certain temperatures, the viscosity curves exhibit a Newtonian behavior at low shear rates, followed by two distinct shear-thinning phenomena. In some cases, the first shear-thinning is preceded by a small shear-thickening region. Similar phenomena are not present in the viscosity curves of the RET-modified asphalts and can be related to a temporary nature of the physical polymer network.

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Section: Discussionmentioning

confidence: 85%

Temporary networks in polymer‐modified asphalts

Polacco

Stastna

Vlachovicova

et al. 2004

Polymer Engineering & Sci

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“…The poly(styreneblocli-2-vinylpyridine) copolymer is designated S2VP(13-IS), where the numbers in parentheses refer to the number-averaged molecular weights in kglmol of the PS and P2VP blocks, respectively. The P2VP homopolymer is designated P2VP (20), where the number in parentheses refers to the number-averaged molecular weight in kglmol. The measured polydispersity of S2VP (13-15) was 1.10, while the that of P2VP(20) was 1.12.…”

Section: Methodsmentioning

confidence: 99%

“…In Figure 1 la we show DSC thermograms from the q!~~= 0.40 in S2VP copolymer and a dp = 0.28 sample in P2VP (20) homopolymer at a 10 OC/min scan rate. Both samples exhibit a qualitatively similar crystallization transition followed by melting transition, demonstrating that crystallization induced by microphase separation of the block copolymer does not play a role in this unusual transition.…”

mentioning

confidence: 99%

Phase Behavior of Polystyrene-block-poly(2-vinylpyridine) Copolymers in a Selective Ionic Liquid Solvent

Virgili

Hexemer²,

Pople

et al. 2009

Macromolecules

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The phase behavior of poly(styrene-block-2-vinylpyridine) copolymer solutions in an imidazolium bis(trifluoromethane)sulfonamide ([Im][TFSI]) ionic liquid has been studied using small-angle X-ray scattering (SAXS) and optical transmission characterization. Through scaling analysis of SAXS data, we demonstrate that the [Im][TFSI] ionic liquid behaves as a selective solvent toward one of the blocks. We observe lyotropic and thermotropic phase transitions that correspond qualitatively to the phase behavior observed in block copolymer melts and block copolymer solutions in molecular solvents. In addition, we have studied the thermal properties of block copolymer solutions in the ionic liquid using differential scanning calorimetry and wide-angle X-ray scattering. We observe distinct composition regimes corresponding to the change in the block copolymer's glass transition temperature, Tg, with respect to the concentration of polymer in ionic liquid. At high block copolymer concentrations, a "salt-like" regime corresponding to an increase in the block copolymer Tg is observed, while at intermediate block copolymer concentrations, a "solvent-like" regime corresponding to a decrease in the block copolymer T, is observed. An unusual thermal transition consisting of crystallization and subsequent melting of the ionic liquid is observed at the lowest block copolymer concentration characterized.

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“…[1][2][3][4][5][6][7][8] A wide range of micelle morphologies of block copolymers in solutions have been recently reported, and these morphologies possess better stability than those formed by small-molecule amphiphiles such as surfactants. [9][10][11][12][13][14][15] These block copolymer micelles can be potentially used in specific biological and medical applications.…”

Section: Introductionmentioning

confidence: 99%

Self‐assembled, wormlike‐cylinder network of polystyrene‐block‐poly(ethylene oxide) micelles in solution

Bhargava¹,

Zheng²,

Quirk³

et al. 2006

J Polym Sci B Polym Phys

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ABSTRACT:We report the formation of a highly entangled and interconnected, selfassembled, wormlike-cylinder network of polystyrene-block-poly(ethylene oxide) in N, N-dimethylformamide/water. In this system, N,N-dimethylformamide was a common solvent and water was a selective solvent for the poly(ethylene oxide) blocks. The degrees of polymerization of the polystyrene and poly(ethylene oxide) blocks were 962 and 227, respectively. The network was formed at copolymer concentrations higher than 0.4 wt % and consisted of self-assembled, wormlike cylinders that were interconnected by Y-shaped, T-shaped, and multiple junctions. The network morphology was visualized with transmission electron microscopy. Capillary viscometry measurements revealed an order-of-magnitude increase in the inherent viscosity of the colloidal system upon the formation of the network. A similar effort to obtain a wormlike-cylinder network in an N,N-dimethylformamide/acetonitrile system, in which acetonitrile was a selective solvent for the poly(ethylene oxide) blocks, was unsuccessful even at high copolymer concentrations; instead, the wormlike cylinders showed a tendency to align. The viscosity measurements also did not show a substantial increase in the inherent viscosity. Thus, the solvent played a critical role in determining the formation of the self-assembled, wormlike-cylinder network. This formation of the network resulted from an interplay between the end-capping energy, bending energy (curvature), and configurational entropy of the self-assembled, wormlike-cylinder micelles that minimized the free energy.

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Theory of micelle formation in block copolymer-homopolymer blends

Cited by 196 publications

References 6 publications

Temporary networks in polymer‐modified asphalts

Temporary networks in polymer‐modified asphalts

Phase Behavior of Polystyrene-block-poly(2-vinylpyridine) Copolymers in a Selective Ionic Liquid Solvent

Self‐assembled, wormlike‐cylinder network of polystyrene‐block‐poly(ethylene oxide) micelles in solution

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