Double-diamond structure

It is well known that block copolymers and graft copolymers composed of incompatible sequences form the self-assemblies (the microphase separations). These morphologies of the microphase separation are governed by Molau s law [1] in the solid state. Nowadays, not only the three basic morphologies but also novel morphologies, such as ordered bicontinuous double diamond structure, are reported [2-6]. The applications of the microphase separation are also investigated [7-12]. As one of the applications of the microphase separation of AB diblock copolymers, it is possible to synthesize coreshell type polymer microspheres upon crosslinking the spherical microdomains [13-16]. 

Star molecules containing branches made of two blocks have also been prepared by these methods102 103. Recently it was shown that such star-block copolymers exhibit very interesting so-called double-diamond structures in the bulk owing to segregation due to incompatibility between chemically unlike blocks 104. ... 

Many more examples of interpenetration in inorganic chemistry lead to a recognition of the ubiquity of hyperbolic surfaces of infinite genus -exemplified by three-periodic minimal surfaces - that demands consideration. In the giant structure of Cu4Cd3 the Cu atoms are separated from the Cd atoms by a surface that resembles a minimal surface. In diamond, cubic ice and cristobalite, all the atoms are located on one side of the surface and the space on the other side is empty. If ice is subjected to very high pressure, the same structure appears on both sides of a minimal surface (double ice or ice IX), with almost double the density of ordinary ice (Fig. 2.8). Similarly, diamond is expected to transform to a double-diamond structure with metallic properties at sufficiently high pressure. 

Figure C2.1.11. Morphologies of a microphase-separated di-block copolymer as function of the volume fraction of one component. The values here refer to a polystyrene-polyisoprene di-block copolymer and ( )pg is the volume fraction of the polystyrene blocks. OBDD denotes the ordered bicontinuous double diamond structure. (Figure from [78], reprinted by permission of Annual Reviews.)...

For the 7-16-7 polymers, the microphase was lamellar. Both these sets of results are consistent with the NSCFT predictions for these compositions. The 10-10-10 chains formed the bicontinous double-diamond structure. This contrasts with the NSCFT prediction that the gyroid phase is stable, but it is modest disagreement given that the NSCFT predicts that the double-diamond structure is metastable, and the energy difference between the two is small. 

Matsushita, Y., Tamura, M., andNoda, 1. (1994) Tricontinuous double-diamond structure formed by astyrene-isoprene-2-vinylpyridine triblock copolymer. Macromolecules, 27,3680-3682. 

Recently, the bicontinuous double diamond structure Pri3m, Q224 space group) has been experimentally observed in a BCP system [24]. It is believed to be... 

Although a few 3D isotropic cubic network phases have already been observed, other cubic network phases have stayed elusive in BCP SA, such as the I-WP [25], Neovius [26], K surface [27], and Lidinoid [28] structures (see Fig. 2). Packing frustration of polymer chains in the network nodes of these structures is a primary hurdle for formation of these phases. However, as shown in the cases of the plumber s nightmare and double diamond structures, BCP co-assembly with additive molecules or ordered local packing of monomer units may open new routes to such cubic structures. 

The method described above was applied to the synthesis of star block copolymers (Figure 4), in which each branch was a polystyrene-Z)-polydiene copolymer. Under selected conditions of composition, branch length, and concentration, they exhibit bicontinuous mesomorphic phases referred to as double-diamond structures [29], which had never been observed before. 

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