Wormlike micelles nematic phases

Nieh MP, Raghunathan VA, Glinka CJ, Harroun TA, Pabst G, Katsaras J (2004) Magnetically alignable phase of phospholipid bicelle mixtures is a chiral nematic made up of wormlike micelles. Langmuir 20 7893-7897... 

Still in the isotropic phase, but closer to the phase transition temperature, a shear induced transition to the nematic phase occurs, see Fig. 6. Based on the equations presented here, such a behavior has been predicted theoretically quite some time ago [20, 21]. This phenomenon has been observed in lyotropic liquid crystals, in particular with wormlike micelles [5] and in side-chain liquid-crystalline polymers [35]. In Fig. 6, results are presented for = 1.3. For comparison, the highest temperature for which a metastable nematic phase exists, -d = 9/8 = 1.125, is included. For imposed shear rates, shear stress and consequently the viscosity jump smaller values at the induced phase transition. For imposed shear stress there is a jump to higher shear rates. 

For semiflexible chains characterized by contour length much larger than persistence length, Semenov and Kokhlov demonstrated that the values of the phase boundaries between the isotropic and nematic states, as well as the order parameter of the nematic phase could be predicted [291], Following Onsager [277], it was shown that the boundary Ci-m depends only on the ratio between the radius and the persistence length [277,291,292], For nematic wormlike micelles, this limit was found to vary between 20 and 45 wt. %, in fair agreement with the theoretical values [44],... 

Although polymers and wormlike micelles are very different in nature, the flow properties of their nematic phases are similar. This property was ascribed to the existence of textures at a mesoscopic scale, and to the fact that the dynamics of the textures dominate the mechanical responses of these fluids [310]. 

Kadoma I A, van Egmond JW (1998) Flow-induced nematic string phase in semidUute wormlike micelle solutions. Phys Rev Lett 80(25) 5679-5682... 

Berret JF, Roux DC, Lindner P (1998b) Structure and rheology of concentrated wormlike micelles at the shear-induced isotropic-to-nematic transition. Eur Phys J B 5(l) 67-77 Berret JF, Porte G (1999) Metastable versus unstable transients at the onset of a shear-induced phase transition. Phys Rev E 60(4) 4268-4271... 

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