Elongational behavior of sphere-forming triblock copolymers is examined using a series of sample having almost the same molecular weight but different bridge fractions prepared by mixing polystyrene-b-polyisoprene-b-polystyrene (SIS) and the cyclic-SI. A polystyrene-b-polyisoprene-b-poly(2-vinylpyridine) sample was also used as a 100% bridged reference. The lattice deformation examined by SAXS can be well expressed by affine deformation, independent of the bridge fraction. Macroscopic stress and the orientation function of I segments examined by IR dichroism can be also approximately expressed by affine deformation, where magnitudes are proportional to the bridge fraction. In the stress-strain curves, small shoulders were observed at low strains. The presence of the shoulder can be explained by restoring force of the lattice, the magnitude of which depends on the regularity of the microdomain lattice. It is found that the restoring force linearly depends on the bridge fraction of the middle block chains in bulk states, in contrast to the results reported for solvent-containing systems.
All Science Journal Classification (ASJC) codes
- Organic Chemistry
- Polymers and Plastics
- Inorganic Chemistry
- Materials Chemistry