Micelles, worm-like

J. S. Pedersen, M. Laso, P. Schurtenberger. Monte Carlo study of excluded volume effects in worm-like micelles and semi-flexible polymers. Phys Rev E 54 R5917-R5920, 1996. 

Meijer et al. [135] further studied aggregation phenomena of amphiphilic copolymers obtained by modifying the termini of the dendrimer units of the above series with carboxylic acid groups (49). TEM experiments indicated that all block copolymers formed large aggregates except third generation copolymer which formed worm-like micelles. 

Instead of the familiar sequence of morphologies, a broad multiphase window centred at relatively high concentrations (ca. 50-70% block copolymer) truncates the ordered lamellar regime. At higher epoxy concentrations wormlike micelles and eventually vesicles at the lowest compositions are observed. Worm-like micelles are found over a broad composition range (Fig. 67). This morphology is rare in block copolymer/homopolymer blends [202] but is commonly encountered in the case of surfactant solutions [203] and mixtures of block copolymers with water and other low molecular weight diluents [204,205]. 

Fig. 67 Schematic of phase behaviour for blend of novolac epoxy resin with nearly symmetric poly(methyl acrylate-co-glycidylmelhacrylate)-0-polyisoprene. Ordered L can be swollen with up to about 30% of resin before macroscopic phase separation occurs, producing heterogeneous morphologies containing various amounts of L, C, worm-like micelles and pristine epoxy. At lower concentrations, disordered worm-like micelles transform into vesicles in dilute limit. According to [201]. Copyright 2003 Wiley...

TEM measurements revealed clustering of aggregates in all cases except for PS-de dr-(COOH)8 for which individual worm-like micelles were observed. 

Shear-induced Worm-like micelles, bundle- Manski et al.,... 

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.

PS-PB-PS = 70.10% M, = 101, 14% Ethyl acetate Formation of worm-like micelles from spherical micelles, associated with cloud point Turbidometry, TEM. SLS Canham et at (1980)... 

Macrophase separation after microphase separation has been observed in an AB block copolymer/homopolymer C blend (Hashimoto et al 1995). Blends of a PS-PB starblock copolymer (75wt% PS) and PVME homopolymer were prepared by solvent casting. Binary blends of PS and PVME exhibit a lower critical solution temperature (LCST), i.e. they demix at high temperatures. The initial structure of a 50% mixture of a PS-PB diblock and PVME shown in Fig. 6.20(a) consists of worm-like micelles. Heating led to macrophase separation as evident... 

Marquesa, C.M., Turner, M.S., and Cates, M.E. "Relaxation mechanisms in worm-like micelles". J. Non-Cryst. Solids 172-174,1168-1172 (1994). 

Panizzay, P., Cristobal, G., and Curely, J. "Phase separation in solution of worm-like micelles a dilute n—>0 spin-vector model". ]. Phys. Condens. Matter 10,11659-11678 (1998). 

Surfactant solutions with rod-like micelles can have notable viscosities up to six times higher than the water viscosity [37]. This can be explained by the presence of entangled rodlike micelles (often also called worm-like micelles or thread-like micelles) which arrange themselves in a supramolecular transient network [38-41 ]. Such solutions often have elastic properties but they do not show a yield stress. This means that even high viscous solutions flow under the influence of very small shear stress. In this situation they show a zero shear viscosity which is given by ... 

Block copolymers self-assemble to form nanoscale organized structures in a selective solvent. The most common structures are spheres, with the insoluble core surrounded by a solvent-swollen corona. In some instances, disk- or worm-like micelles form, and are of particular interest, since the control of their association can lead to a broad range of new applications [1,2]. An important subset of block copolymer micelles are those which contain metal atoms, through covalent attachment or by complexa-tion [3], These structures are interesting because they take advantage of the intrinsic properties of their components, such as the mechanical properties of the polymer micelles and the optical and magnetic characteristics of the metal atoms. Moreover, the assembly permits the control of the uniformity in size and shape of the nanoparticles, and it stabilizes them. 

F SCISS energy of scission of a worm-like micelle ... 

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