Order-to-disorder transition in a diblock copolymer studied at ultrasonic frequencies with a shear wave reflection technique
Deutsches Kunststoff-Institut Darmstadt Schloßgartenstr.
6, D-64289 Darmstadt, Germany
2 Foundation for Research and Technology-Hellas (FORTH) Institute of Electronic Structure and Laser P.O. Box 1527, 71110 Heraklion, Crete, Greece
Accepted: 8 September 2000
The order-to-disorder transition (ODT) has been studied in a poly(styrene-b-isoprene) diblock copolymer with conventional rheology and an ultrasonic shear wave reflection technique. Despite the operational frequency in the latter experiment () being much higher than the critical frequency , the storage modulus exhibits a discontinuous increase at the same temperature at which in conventional rheology a discontinuous decrease is obtained. This results from a change in the mixing law at the ODT. The method constitutes a non-destructive probe of the viscoelastic properties of “soft” materials in the vicinity of phase transitions.
PACS: 61.41.+e – Polymers, elastomers, and plastics / 64.60.Cn – Order-disorder transformations; statistical mechanics of model systems / 62.80.+f – Ultrasonic relaxation
© EDP Sciences, 2000