Effect of Hydrostatic Pressure on Closed-Loop Phase Behavior of Block Copolymers

Abstract

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(LDOT)) at 175 degrees C, and then an upper order-to-disorder transition temperature (T(UODT)) at 255 degrees C. With increasing pressure both T(LDOT) and T(UODT) were markedly changed, where dT(LDOT)/dP was 725 degrees C/kbar and dT(UODT)/dP was -725 degrees 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.

Pressure-induced reentrant micellization of amphiphilic block copolymers in dilute aqueous solutions

“…[10][11][12][13] Schwahn et al observed an abnormal pressure dependence of a phase boundary of poly͑ethylethylene͒-block-poly͑dimethylsiloxane͒, and explained it with a dominating increase in the entropic term of the Flory-Huggins interaction parameter. Pressure dependence of phase transitions in polymer blends and block copolymers has been a subject of intense research both experimentally and theoretically.…”

“…Pressure dependence of phase transitions in polymer blends and block copolymers has been a subject of intense research both experimentally and theoretically. 13 In the case of polymer-aqueous systems, polymer solutions 4, [14][15][16][17][18][19] and gels 17,20 were extensively studied in order to reveal pressure effects on solubility, and different phase behaviors between at low and high pressures were obtained. 12 Ryu et al reported a closed-loop pressure-temperature ͑P-T͒ phase curve for poly͑styrene͒-block-poly͑n-pentyl methacrylate͒.…”

Hot melt extrusion: An emerging manufacturing method for slow and sustained protein delivery

“…In addition to these commercially available polymers, baroplastic is an emerging material that could potentially be applied for the use of HME in pharmaceutical proteins. Baroplastic is a type of block‐copolymers that could perform melt‐like behavior induced by pressure (Ruzette et al, 2003; Ryu et al, 2003). These polymers normally contain nanophase domains of a high glass transition temperature ( T g ) (the hard segment) and a low‐ T g component (the soft segment) (Cho, 2012).…”

Baroplastic Process of PBA/PS/Si Blend Prepared by Heterocoagulation

“…특히, 최근 많이 연구되고 있는 압력가소성 고분자 (baroplastic polymer) [13][14][15][16] 또한 고분자의 계면과 밀접히 연관 되어 있어, 고분자 블렌드의 역할이 기대되는 분야이다. 인가 된 압력에 의해 고분자 계면에서 상변화가 유도될 수 있는 압 력가소성은 문헌에 17 정리되어 있는 것과 같이 polystyrene-bpoly(alkyl methacrylate)(PS-b-PAMA) 계열 [18][19][20][21] 및, polystyreneb-poly(butyl acrylate)(PS-b-PBA)의 22 블록공중합체와 poly(butyl acrylate)/polystyrene(PBA/PS), poly(ethylhexyl acrylate)/polystyrene(PEHA/PS) 23…”