Self-Assembly of Block Copolymers as a Template

In order to overcome the lower limit of cell size, we need to employ artificial nuclei of cells with much smaller size. One of the possible strategies to employ small nuclei for carbon dioxide bubbles is the use of self-assembled block copolymer domains with a high affinity to carbon dioxide. We describe in this section how fluorine-containing block domains of block copolymers work as nuclei and how a nanometer-size cell (nanocell) can be introduced in each fluorine-containing block domain. 

Block copolymers are a class of soft matter that self-assemble into nanoscopic periodic domain structures, as extensively described throughout this book (Bates and Fredrickson, 1990 Lazzari and Lopez-Quintela, 2003 Park et al, 2003). The size of block copolymer domains typically ranges from 5 to 100 nm, primarily depending on the molecular size of the block copolymers. 

The symmetry of the block fraction plays an important role in determining which morphology is selected by a particular block copolymer from a class of ordered morphologies, such as spheres, cylinders, gyroids and lamellae. 

We first focus on fluorine-containing block copolymers that form spherical domains of a fluorine-containing block since they provide well-ordered and densely packed spherical nuclei for nanobubbles of carbon dioxide, which lead to closed nanocells. Such spherical domains of fluorine-containing blocks are expected to work as a template to provide nanocells, which are cells on a nanometer scale and much smaller than conventional microcells using homopolymers and supercritical carbon dioxide. In order for spherical domains to work as nuclei for nanobubbles, an affinity of fluorine-containing domains to carbon dioxide higher than that of the other block domains is essential. 

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