Block copolymers mesophases

Thomas, A. Schlaad, H. Smarsly, B. Antonietti, M. 2003. Replication of lyotropic block copolymer mesophases into porous silica by nanocasting Learning about finer details of polymer self-assembly. Langmuir 19 4455 1459. 

In the second part of this chapter recent progress towards nanostructured polycrystalline assemblies from block copolymer mesophases will be described. First, developments in the approaches presented so far toward nanostructured materials with crystalline nanoparticles embedded in an amorphous silica-type material will be discussed. The second section will describe a new assembly approach for the development of nanostructured materials with highly crystalline walls. The last part highlights achievements of the self-assembly of block copolymers with... 

C.Z. Yu, B.Z. Tain, J. Fan, B. Tu, and D.Y. Zhao, Synthesis of Hierarchically Arrayed Silica Nanorods via Reverse Amphiphilic Block Copolymer Mesophases. Chem. J. Chin. Univ.-Chin., 2003, 24, 5-8. 

Long-wavelength deformations/fluctuations in block copolymers are important for several reasons. First, they are responsible for the mechanical properties of a block copolymer mesophase. Second, they determine the degree of long-range order and the effects of defects in the ordered phases. Finally, they are responsible for certain novel long-wavelength instabilities. 

Liquid crystals combine properties of both liquids (fluidity) and crystals (long range order in one, two, or three dimensions). Examples of liquid crystalline templates formed by amphiphiles are lyotropic mesophases, block copolymer mesophases, and polyelectrolyte-suxfactant complexes. Their morphological complexity enables the template synthesis of particles as well as of bulk materials with isotropic or anisotropic morphologies, depending on whether the polymerization is performed in a continuous or a discontinuous phase. As the templating of thermotropic liquid crystals is already described in other reviews [47] the focus here is the template synthesis of organic materials in lyotropic mesophases. 

Fig. 1.8 Nano-objects with controlled shape and size from block copolymer mesophases At the top left, phase-separated PI-b-PEO is shown, where the spheres consist of the PEO block. Subsequent dispersion and sol-gel hydrolysis of silicon and aluminum alkoxides in the PEO block leads to swelling of this block and, if desired, morphological transitions. Dissolution of the PI block in a selective solvent leads to hai nano-objects consisting of cross-linked silica/alumina/PEO (Adapted from [62]).

Y.L. Loo, R.A. Register Crystallization within block copolymer mesophases. In Developments in block copolymer science and technology, ed by I.W. Hamley (Wiley, New York 2004). 

Block copolymers with both hydrophilic and hydrophobic properties have been used by Garcia et al. in the synthesis of nanoparticles [43]. Reverse block copolymer mesophases have been used to prepare iron oxide-aluminosUicate nanoparticles. 

Garda, C.B.W., Zhang, Y.M., Mahajan, S., DiSalvo, F. and Wiesner, U. (2003) Self-assembly approach toward magnetic silica-type nanoparticles of different shapes from reverse block copolymer mesophases. Journal of the American Chemical Society, 125(44), 13310-11. 

Improved numerical algorithm for exploring block copolymer mesophases. Journal of Polymer Science Part E Polymer Physics, 40,1777-83. 

Loo YL, Register AR. Crystallization within block copolymer mesophases. In Hamley IW, editor. Developments in Block Copolymer Science and Technology. New York Wiley 2004. 

Technical problems of simulations of block copolymer mesophases... 

In principle, one could generalize the considerations of Section 7.2.4 to a study of block copolymer mesophase ordering, by suitable identification of the order parameter of the transition. For the lamellar mesophase (Fig. 7.2), this order parameter is written in terms of concentration waves for the local concentration of component A, for instance... 

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