Perforated lamellar structure

A sketch of the perforated lamellar morphology is depicted in Fig. 2. Depending on the point of view, the 2D projection exhibits different patterns perpendicular to the layers of the perforated lamellar structure the projection appears like a hexagonal honeycomb mesh (Fig. 2a). By contrast, the parallel view (Fig. 2b) leads to rows of spots. 

Fig. 2 Sketch of perforated layers (PL) or catenoid structure, a Projection direction perpendicular to layers of perforated lamellar structure appears as a hexagonal honeycomb mesh, b Projection parallel to layers appears as rows of dark spots resulting from cross section of parts. Sketch according to [15]. Copyright 2001 American Chemical Society...

Fig. 9 Tetragonal perforated lamellar structure in an AB-BA sequence formed by tetra-branched triblock molecule...

Fig. 15 Self-assembly of coil-rod-coil molecule 25 into the hexagonal perforated lamellar structure and subsequent conversion to hexagonal closed-packed bundles...

Fig. 21 Perforated lamellar structure hierarchically formed by poly(slyrcne-t>-(2,5-bis[4-methoxyphenyl] oxycarbonyl)styrene) structure. Reprinted with permission from [107]. 2005 American Chemical Society...

A simple molecular model was used to simulate the equilibrium phase behaviour of hybrid materials for different inorganic precursors. Although some physical and chemical properties are not explicitly included in the model, it is possible to detect the general behaviour of the system such as the phase separation and the self-assembly of surfactants in hexagonal, lamellar or perforated lamellar structures. 

A woodpile structure, a similar layered structure with an unidentified space group similar to the 070 space group (Fddd), was observed in a BCP/aluminosilicate assembly [9]. In contrast to the perforated lamellar structure, zig-zag cylinders are stacked layer-by-layer (see Fig. 2). Although a zig-zag cylinder is usually energetically less stable than a parallel cylinder due to larger interfacial energy, the relaxed chain conformation of polymer chains, leading to a reduced entropic penalty, may allow the zig-zag cylinder formation. 

In the system of SIO more detailed studies around the order-disorder transition were carried out starting from a symmetric SI diblock copolymer with an increasing amount of PEO as the third block, between the lamellar diblock copolymer and the lamellar triblock terpolymer. Besides the core-shell cylindrical and core-shell gyroid stmctures, pillared and perforated lamellar structures were found for compositions close to the lamellar diblock copolymer and lamellar triblock terpolymer, respectively. We will come back to this system when discussing blends in Section 7.02.2.3.2. 

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