Grains, block copolymer domains

Fig. 5.13 When confined to a thin fihn, the orientation of block copolymer domains with respect to the substrate surface is crucial for many applications, (a) Lamellae lying parallel to the substrate, (b) lamellae aligned perpendicular, (c) cylinders lying parallel, (d) cylinders perpendicular, and (e) spheres. In the case of lamellae in the perpendicular orientation and cylinders in parallel, lines can be patterned if the persistence length of the structure can be controlled. In the case of upright cylinders and spheres, the grain size and perfection of the hexagonal array is of primary importance. Reproduced with permission from ref. [105]...

The self-assembly of block polymers, in the bulk, thin film and solution states, produces uniformly sized nanostructured patterns that are very useful for nanofabrication. Optimal utilization of these nanoscopic patterns requires complete spatial and orientational control of the microdomains. However, the microdomains in the bulk state normally have grain sizes in the submicron range and have random orientations. In block copolymer thin films, the natural domain orientations are generally not desirable for nanofabrication. In particular, for composition-asymmetric cylindrical thin films, experimental... 

Let us describe another recent development in TEMT - new TEMT employed to cover mesoscaie structures. As mentioned in Section 2.20.2, there is a spatial gap in 3D microscopy (see Figure 1). In polymer science, the hierarchical nature of polymer stmctures has to be seamlessly examined from a few to several hundreds of nanometers. In block copolymer nanos-tmctures, for example, the smallest stmctural elements, such as spheres, cylinders, and lamellae, are of the order of several nanometers to several tens of nanometers, which can be examined by existing TEMT. The upper hierarchical stmcture of such stmctural elements is the grain. The size and internal domain orientation of the grains, the mesoscaie stmctures, are too large to be observed by existing TEMT. 

Block copolymers composed of immiscible blocks form nanodomains, and this domain stmcture and a higher order grain stmcture strongly influence the rheological property. " Sometimes, we may estimate the domain stmcture from this property. A brief description of the method of estimation is also included in this section. 

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