Micelle morphology

One unifying rule accounting for block copolymer micelle morphology has been proposed by Discher and Eisenberg [239]. This rule should be considered for coil-coil block copolymer readily soluble in the selective solvent and is expressed as a function of the mass fraction of the hydrophilic block to total mass of the copolymer (/hydrophilic)-... 

Fig. 2.35 Transition from folded lace to worm-like micelle morphology in an /PS = 0.81 I2S copolymer (Pochan et al. 1996a). (a) TEM image of folded-lace structure, following annealing of the sample at 120°C for 1 week (0s04 was used to selectively stain the PI) (b) randomly oriented worm structure after annealing at 125 °C for 20 days (c) Schematic of the transition from lamellae via folded-lace to worm-like micelles.

Figure 18a,b displays SFM images of SV films that have been prepared from chloroform and from toluene solutions, respectively. The mixed pattern of featureless areas and round-shaped stripes in Fig. 18a can be identified as in-plane lamella and perpendicular-oriented lamellae, respectively. The microstructure prepared from toluene solutions (Fig. 18b) is attributed to P2VP micelles surrounded by the PS shell. The micelle morphology is a result of the SV self-assembly in a selective solvent [119], We have made use of this morphological difference to study the microstructure response to solvent uptake by block copolymer films. 

The predictions of ( )CMC were extended to cylindrical and lamellar micelle morphologies [Shull et al., 1991]. In all cases, geometric parameters, e.g., core radius and corona thickness, can be computed, assuming that the interfacial thickness between the core and the corona is equal to Al, . ... 

Figure 2 The different micelle morphologies formed in Pluronic block copolymer systems.

Figure 29 Effect on surfactant micelle morphology by addition of a hydrophobically modified associative polymer.

Figure 4.7. The control of micelles morphology hy changing the solvent conditions. Representative TEM pictures showing the reversibility of various morphological transitions for a solution of 1% (w/w) poly(styrene)3io-b-poly(acrylic acid)52- [Reprinted from Shen, H. et al. Copyright 1999, with permission from American Chemical Society].

Figure 9 Top cartoon representations of a spherical micelle, a wormlike micelle, and a vesicle. The red blocks represent the solvophilic blocks, and the blue blocks represent the solvophobic blocks. Bottom example TEM images showing diffa-ent micelle morphologies adopted by block copolymers in solution, (a) Spherical micelles formed from polyfethylene oxide)-f>-polycaprolactone (PEO-f>-PCL) copolymers.(b) Wormlike micelles, vesicles, and octupi formed by mixing PEO-fc-polybutadiene (PEO-fc-PB) block copolymers. (Reproduced from Ref. 32. American Chemical Society, 2004.) (c) Vesicles formed from PEO-f>-PCL copolymers. (Reproduced from Ref. 33. Royal Society of Chemistry, 2011.) (d) Multicompartment micelles formed from a triblock copolyma-. (Reproduced from Ref. 34. American Chemical Society, 2010.) (e) Stomatocytes formed using PEO-f>-polystyrene (PEO-f>-PS) copolyma-s. (Reproduced from Ref. 35. American Chemical Society, 2010.) (f) Toroidal micelles coexisting with cylindrical micelles and sphaical micelles formed from poly(acrylic acid)-f>-poly(methacrylic acid)-fc-PS (PAA-f>-PMA-f>-PS) triblock copolymers. (Reproduced from Ref. 36. Royal Society of Chemistry, 2009.)...

Figure 3 Correlation of packing parameter for a given amphiphile with the resultant solution self-assembled micelle morphology. (Reproduced from Ref. 3. Elsevier, 2005.)...

One of the most widely used membranes today is Nafion, a polymer ereated by the DuPont eompany. Nafion (Figure 1.11(e) [13]) has an aliphatic perfluorinated backbone with ether-linked side ehains ending in sulfonate cation exchange sites [14, 19]. It is a eopolymer of tetrafluoroethylene and sulfonyl fluoride vinyl eflier [20] and has a semi-erystalline structure [21]. This structure, which resembles Teflon, gives Nafion long-term stability in oxidative or reductive conditions [12]. In the dry state it has reverse micelle morphology, in which the ionic clusters are... 

The chemical potential of a copolymer chain in a micelle was evaluated by Semenov [278] for long homopolymer chains (P > N), which do not penetrate the micelles. Depending on the diblock copolymer composition, the micelle morphology could be spherical, cylindrical, or lamellar [278, 289]. The chemical potential of a diblock copolymer chain in a micelle formed within the B phase is then given by [55, 56, 278] ... 

Olympus 1X71 inverted fluorescence microscope with a 60X objective and a Cascade CCD camera was used to visualize OCL worm micelles. A hydrophobic fluorophore dye (PKH 26) was added to the OCL worm micelles, and 2 pL sample was used in the glass slide-cover slip chamber and approximately 20 pictures were taken per sample. Analysis detail was described elsewhere (2S). Cryo-TEM was also used to visualize OCL worm micelle morphological change. Sample preparation and analysis was described elsewhere. 14)... 

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