We have used dynamic oscillatory measurements to locate the temperature of the microphase separation transitio (TMST) for a series of nearly monodisperse styrene-isoprene diblock (SI) and triblock (SIS) copolymers, all containing 13 wt % styrene and ranging in molecular weight from 48K to 149K. The microphase-separated morphology in all cases is a disordered (liquidlike) arrangement of polystyrene spheres in a polyisoprene matrix, as determined by small-angle X-ray scattering. Values of TMST were obtained from isochronal plots of the storage modulus versus temperature. The marked change in slope at the MST demonstrates that even materials with a disordered microdomain structure can experience significant property changes when the MST is traversed. The diblock and triblock TMST values are consistent with a single ϰ(T) relation, indicating that large-scale polymer architecture has little effect on ϰ.
All Science Journal Classification (ASJC) codes
- Organic Chemistry
- Polymers and Plastics
- Inorganic Chemistry
- Materials Chemistry