Small-Angle Scattering Studies of Block Copolymer Micelles, Micellar Mesophases and Networks

Abstract

This chapter describes the use of small-angle neutron scattering to study block copolymer micellar phases. The technique provides experimental values for size and form of the polymers, as well as their aggregates. It gives information about aggregation number and aggregation thermodynamics. The scattering experiments also provide information about the interactions between polymeric aggregates. The chapter gives details of positional correlations between these structures, including detailed information on ordered structures. In dense systems, the small-angle technique is used to study thermodynamics of the disorder-to-order phase transitions, and to study details of the ordered phases. It is shown that aqueous systems of triblock copolymers composed of poly(ethylene oxide) and poly(propylene oxide) have not only interests for applications, but constitute a very good model system in which a variety of thermodynamics can be studied. This includes, for example, the unimer-to-micelle self-assembling, micellar sphere-to-rod shape transformation, micellar hard-sphere crystallization into cubic or hexagonal order, and order-to-bicontinuous phase transitions. The information obtained from scattering experiments can be used directly in the design and optimization of new polymeric materials.