Anisotropic gels

Hikmet and Poels have reduced the percentage of difunctional monomer (Fig. 3) in the same type of mixture even further to less than 1 % in order to obtain anisotropic gels. Although holographic gratings were not reported, switchable gratings of 100 p,m from a mask showed very promising results [28],... 

This chapter deals primarily with examples in the semidilute concentration range, corresponding to overlapped chainlike aggregates of isotropic gels." As mentioned, the heterogeneity of the networks makes possible the existence of more concentrated microdomains, where chains are somewhat ordered in crystalline or lyotropic structures (corresponding to anisotropic gels). 

Zhao, Y., Chenard, Y., and Paiement, N. Liquid crystalline anisotropic gels based tin azobenzene-containing networks. Macromolecules 33, 1049 (2000). 

In order to investigate the direction-dependent relaxation time of isotropic as well as anisotropic gels, swelling kinetics experiments were performed. Filler-loaded spherical mPDMS samples with an initial diameter of 2 cm were used for the experiment. The gel samples were placed into cyclohexane, and the diameter of the gel was recorded by a digital Sony video camera (DCR-TRV40E). 

Many techniques have been proposed for making capillary-pore membranes including laser beams, electroforming, photochemical etching, and ionotropy to orient anisotropic gel particles to form ionotropic-gel membranes.3... 

Guan L, Zhao Y. 2000. Self assembly of a liquid crystalline anisotropic gel. Chem Mater 12 3667 3673. 

Maki Y, Furusawa K, Yasuraoka S et al (2014) UnivCTsality and specificity in molecular orientation in anisotropic gels prepared by diffusion method. Carbohydr Polym 108 118-126... 

In practice, a great many anisotropic gels are met with. The anisotropy is invariably due to an orientation of the dements building up the framework structure. Anisotropy may reveal itself in various ways, as e. g. in the form of anisotropy of... 

Anisotropic gels produced in the laboratory owe their orientation to a previous deformation. This may be either effected by mechanical deformation of an isotropic gel or by preventing the gel from isotropic contraction, for instance during drying. In both cases the random orientation of the structural elements of the frame work is changed into a more or less preferred one in one or two directions of space. 

Anisotropic gels are a mixture of a solid crosslinked LC network and non-reactive low molar mass LCs [33] produced by the in situ polymerization of LC monomers with two polymerizable groups, such as diacrylates, in the presence of low molar mass LCs without reactive units. The resultant solid polymer network incorporates the three-dimensional structure of the original LC mixture. Main aspects around LC networks, especially those involving densely crosslinked solids, that arose from low molar mass bifunctional LC monomers are stated in Chapter 10. Here the description focuses only on some specific and innovative system, especially for the networks formed by the moderate crosslinking of preformed linear polymers. 

---