Block copolymers, microdomain related properties

As the specific properties of block copolymers are related to the formation of microdomains, the present review will deal with the shape, size, and arrangements of microdomains in block copolymer systems. The phenomenon of phase separation and of microdomains formation is not restricted to dry copolymers, but is also a characteristic feature of their concentrated solutions, where mesophases are observed11, and, therefore, we shall generally consider systems copolymer/solvent and treat dry copolymers as their limiting case. 

After a brief recall of the methods of synthesis of block copolymers, we shall describe the principal types of organized structures, which have been observed in block copolymers both in mesomorphic and dry states. Then we shall examine the structure and properties of the most important block copolymers dividing them in three categories copolymers with amorphous blocks, copolymers with amorphous and crystallizable blocks, copolymers with blocks presenting biological interest. However, in this review, only such properties will be taken into account that are related to the microdomain structure of block copolymers. 

The theories dealing with the ordered phase were first developed as soon as the fascinating properties of block copolymers became known. Main concerns of these theories were the delineation of the conditions necessary for the formation of spherical, cylindrical or lamellar morphology, the prediction of the size of the microdomains of these morphologies in relation to the block lengths, and the question of the thickness and density profile across the boundary between microphases. These theories were extensively reviewed over the years in monographs and symposium proceedings and will not be discussed further here. 

The increasing importance of block copolymers arises mainly from their unique properties in solution and in the solid state, which is a consequence of their molecular structure. In particular, sequences of different chemical composition are usually incompatible and therefore have a tendency to phase segregate. The microdomain formation process in the solid state is directly related to the specific molecular... 

MICRODOMAIN STRUCTURE AND SOME RELATED PROPERTIES OF BLOCK COPOLYMERS... 

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