Nano phase separation

Several other attempts have been made to model the humidified Nation nano-phase-separated structure and the temperature dependence of proton transport by atomistic MD simulations [53,59-64], It was observed that more filamentous aqueous regions at low humidity change into clusters of more micellar shape at intermediate water content, which connect into channels at high water content [60]. Other studies noted a certain effect of sidechain arrangement (statistical vs. blocks) on the size of the phase-separated regions [59]. These calculations frequently suffer from an ergodicity problem due to the different characteristic time scales of water and polymer. 

Typical phase morphologies of block copolymers are illustrated in Figs. 5.38 0 and 5.79. In the classification of phases, the phase-separated block copolymers are considered to be amphiphilic liquid crystals despite the fact that inside the phase areas the typical liquid-crystalline order is missing (see Sect. 5.5). In this section the question will be addressed what happens when the usually micro- or nano-phase separated block copolymers show solubility, i.e., when the amphiphilic liquid crystal becomes thermotropic, i.e., dissolve at a given temperature. 

Photoreactive nanomatrix structures are novel functional nano-phase separated structures obtained by graft copolymerization, which consist of a dis-persoid of major elastomer and a matrix of minor functional polymer having carbon-carbon double bonds as a photoreactive site. The photoreaction of the polymer in the nanomatrix may cement the nanomatrix structure with not only crosslinking junctions of the elastomer in the dispersoid and chemical linkages... 

If the polymer structure consists of flexible pendant side chains carrying ionic function moieties linked to the polymer main-chain, nano-phase separation between hydrophilic and hydrophobic domains might be improved. 

A third approach is to induce nano-phase separation through block copolymer architecture, whereby acidic ionic groups are concentrated in one of the blocks along the polymer chain. In this regard, multiblock acidic polymers were prepared with a promising morphological structure by polycondensation. 

Block copolymers represent the best-understood and simplest amphotropic materials studied to date. In such macromolecules, two chemically different blocks (e.g., polyst5n ene, PS, and polyisoprene, PI) are joined together by covalent bonds, so that these incompatible blocks cannot separate into distinct macroscopic phases. X-ray diffraction and electron-microscopy have established that the units of block copolymers segregate into microdomains (micro-phase or rather nano-phase separation), and produce well-developed liquid crystalline phases. ... 

Other electronic components can be attached onto the HBC core and the self-assembled side-by-side monolayers provide opportunities to fabricate single molecular devices at the solid/liquid interface. The covalently tethered HBC and pyrene units co-assemble to form stable nano-phase-separated arrays [96]. A significantly different packing of the adlayer of the HBC-pyrene dyad 87 on the basal plane of the HOPG surface has been obtained, as shown in Fig. 3.26. This STM current... 

Figure 3.26. Molecular structure of HBC-Pyrene dyad and its nano-phase separated self-assembled monolayer on the HOPG surface.

Figure 35 Schematic illustration of storage modulus of nano-phase-separated and entangled block copolymers. Redrawn from Kossuth, M. B. Norse, D. C. Bates, F. J. Rheol. 1999,43,167 with permission.

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