The structure of block copolymer melts, solids, solutions and blends

3 The structure of block copolymer melts, solids, solutions and blends 

The effect on structure of confining block copolymers in thin films has been examined, largely using neutron reflectivity and atomic force microscopy. A number of features that result from the constraint of reduced dimensionality have been reported, such as the observation of islands and holes at the surface 

The dynamics of block copolymers melts are as intriguing as their thermodynamics leading to complex linear viscoelastic behaviour and anisotropic diffusion processes. The non-linear viscoelastic behaviour is even richer, and the study of the effect of external fields (shear, electric. ..) on the alignment and orientation of ordered structures in block copolymer melts is still in its infancy. Furthermore, these fields can influence the thermodynamics of block copolymer melts, as recent work has shown that phase transition lines shift depending on the applied shear. The theoretical understanding of dynamic processes in block copolymer melts is much less advanced than that for thermodynamics, and promises to be a particularly active area of research in the coming years. 

The fascinating thermodynamics of block copolymers that results from microphase separation are the subject of the parts 2.2,2.3, and 2.4 of Chapter 2. Part 2.4 is concerned with the complex kinetic processes that accompany phase transitions, and the dynamic processes controlled by the structure of the block copolymer melt. 

There is a substantial body of theoretical work on micellization in block copolymers. The simplest approaches are the scaling theories, which account quite successfully for the scaling of block copolymer dimensions with length of the constituent blocks. Rather detailed mean field theories have also been developed, of which the most advanced at present is the self-consistent field theory, in its lattice and continuum guises. These theories are reviewed in depth in Chapter 3. A limited amount of work has been performed on the kinetics of micellization, although this is largely an unexplored field. Micelle formation at the liquid-air interface has been investigated experimentally, and a number of types of surface micelles have been identified. In addition, adsorption of block copolymers at liquid interfaces has attracted considerable attention. This work is also summarized in Chapter 3. 

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