Sector column structure

When the confined surfaces suffer from a weak interaction with block copolymer, either parallel or vertical lamellar structures for AB diblock copolymer systems under flat and curved confinements could exhibit, as shown in Figure 27. From theoretical predictions (Turner, 1992 Walton et al., 1994) and simulations (Wang et al., 2000 Yin et al., 2004), the frustration between d and L0 could result in the alternative appearance of parallel lamellar and vertical lamellar structures under flat confinements. A question is naturally arisen can both concentric cylinder barrel and sector column structures appear under the curved confinement ... 

Figure 27 Schematic illustrations of lamellar morphologies for AB diblock copolymers under flat and curved confinements. The concentric cylinder barrel structure under curved confinement corresponds to the parallel lamellar structure under flat confinement (left). The sector column structure corresponds to the vertical lamellar structure (right).

Xiao et ah, 2007). The results indicate that the regular parallel lamella structure (the concentric cylinder barrel structure) appears if d and L0 are compatible in both flat and curved confinements, while a vertical or distorted vertical lamellae structure (sector column structure) is observed otherwise. Upon increasing the curvature of the exterior surface K = 1 /ReXr the compatibility span of d and L0 becomes smaller consequently, the formation of the parallel lamella structure (or the concentric cylinder barrel structure) is more difficult. Our MC results in this work are shown in Figure 28 and more details can be referred to (Xiao et ah, 2007). 

Figure 32 Sector column structure (left) and the unit cell with half period of A domain (right).

XN = 30, and N = 20). Lines 1-3 concentric cylinder barrel phase at K= 0.01,0.02, and 0.03, respectively lines 4-6 sector column phase at K = 0.01, 0.02, and 0.03, respectively lines 7-9 complex multilayered sector column phase at K = 0.01, 0.02, and 0.03, respectively, (b) A sketch of morphology transition for a set of competing structures between the concentric cylinder barrel phase and the sector column phase in part (a), where sec means the sector column phase, and conVj means the concentric cylinder barrel structure with N ayer = n. 

The playground of British structural experimentation extended into the commercial sector. Richard Seifert (1910-2001) and Wilem Frischmann (1931-) completed Centre Point, sited on London s east-west divide. The thirty-two-storey tower remains a quite extraordinary structure. An exterior envelope of elements, transoms and mullions integrated into deep embrasures, supports column-free floors. 

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