Polystyrene-block-Polyisoprene Diblock-Copolymer Micelles: Coupled Pressure and Temperature Effects
Gang Cheng, Boualem Hammouda, Dvora Perahia
The structural changes of diblock copolymer micelles under pressure from (200-16,000) psi were investigated using small-angle neutron scattering (SANS). Asymmetric polystyrene-b-polyisoprene (PS-PI) diblock copolymers were dissolved in decane, a selective solvent for PI, to form spherical micelles with a core of PS and a corona of PI. The micellar solutions were pressurized at temperatures of (25 to 60)°C. At room temperature, the increase in pressure from 200 to 16,000 psi caused no changes in the sizes of the micelles. While the micellar solutions remained stable, instantaneous association of micelles was detected. At elevated pressures, increasing temperature did not lead to dissociation of micelles as previously observed under 1 atmosphere; instead, micelles aggregated and evolved into sheet-like structures, reminiscent of a macroscopic phase separation. It was found that higher pressure leads to a faster shape transition.
, Hammouda, B.
and Perahia, D.
Polystyrene-block-Polyisoprene Diblock-Copolymer Micelles: Coupled Pressure and Temperature Effects, Macromolecular Chemistry and Physics, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=915211
(Accessed December 3, 2023)