Melt phase behaviour of block copolymers

The dynamics of block copolymers are equally intriguing, leading to complex linear viscoelastic behaviour and anisotropic diffusion processes. The non-linear viscoelastic behaviour is similarly rich, although 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 properties of ordered structures in block copolymer melts have yet to be fully exploited, but the structural and rheological anisotropy is likely to lead to applications not all of which can be envisaged yet. The precision self-assembly of block copolymers into ordered structures for thin film and interfacial applications has enormous potential. Other applications such as nanoscale templates, membranes and filters could exploit the self-assembly of block copolymers into domains with periods 10-100 nm. The possibilities are limited only by the molecular engineer s imagination. 

A review of the thermodynamics of block copolymer melts prior to the discovery of complex phases was presented by Bates and Fredrickson (1990). Ryan and Hamley (1997) have recently reviewed the morphology of block copolymers containing a glassy component, in the melt and glassy states, and a discussion of complex phases is included. Fredrickson and Bates (1996) and Colby (1996) have reviewed the dynamics of block copolymer melts, of which the former is a par- 

In this chapter we focus on melts of well-defined block copolymers synthesized anionically. i.e. block copolymers with a narrow molecular weight distribution. These polymers serve as model materials for investigating the rich phase behaviour and dynamics of block copolymers in the bulk and in thin films. 

---