All matter consists of one or more phases — regions of space with uniform structure and physical properties. The common phases of H2O (solid, liquid and gas), also known as ice, water and steam, are well known. Similarly, though less familiar, perhaps, polymeric materials also can form different solid or liquid phases that determine their properties and ultimate utility. This is especially true of block copolymers, the self-assembling macromolecules created when a polymer chain of one type ("Block A") is chemically connected with that of a different type ("Block B").