Effect of Hydrostatic Pressure on Closed-Loop Phase Behavior of Block Copolymers
Journal Article
·
· Physical Review Letters
The effect of hydrostatic pressure (P) on closed-loop phase behavior of deuterated polystyrene-block-poly(n-pentyl methacrylate) copolymers [dPS-PnPMA] was investigated by using small-angle neutron scattering and birefringence. For P<20.7 bar, dPS-PnPMA exhibited a lower disorder-to-order transition temperature (T{sub LDOT}) at 175 C, and then an upper order-to-disorder transition temperature T{sub UODT} at 255 C. With increasing pressure both T{sub LDOT} and T{sub UODT} were markedly changed, where dT{sub LDOT}/dP was 725 C/kbar and dT{sub UODT}/dP was -725 C/kbar. These are consistent with predictions by the Clausius-Clapeyron equation using measured values of the volume and enthalpy changes of both transitions. The large pressure coefficients imply that the closed-loop phase behavior observed for PS-PnPMA is an entropic-driven phase transition.
- Research Organization:
- Intense Pulsed Neutron Source (IPNS), Argonne National Laboratory (ANL), Argonne, IL (US); Pohang Univ.; Univ. of Massachusetts; Korea Atomic Research Inst.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 15004338
- Journal Information:
- Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 23 Vol. 90; ISSN 0031-9007; ISSN PRLTAO
- Publisher:
- American Physical Society (APS)
- Country of Publication:
- United States
- Language:
- ENGLISH
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