| 초록 |
A series of polystyrene-b-poly(alkyl methacrylates) (PS-b-PAMAs) that pertain to the weakly interacting BCP homologues exhibited a variety of phase behaviors by varying alkyl chain length (n) in methacrylate unit. In these transitions, the pressure enhances miscibility (or baroplastic) between the two blocks and shows large pressure dependence, except for an ODT type at PS-b-PMMA (n = 1). In this study, we demonstrated the enthalpic and volumetric changes at the phase transitions for symmetric PS-b-PAMAs (n = 1 ~ 6) based on the characteristic phase behaviors, which were measured by the differential scanning calorimetry (DSC) and ellipsometry with increasing temperature. With the enthalpic and volumetric variables at transitions, the pressure coefficient (dT/dP) of transition temperatures was calculated on the basis of the Clausius-Clapeyron equation. The baroplastic BCPs was attributed to the negative volume change on mixing at phase transitions, which could be driven entropically. |
