Isotropic transition behaviour of an amphiphilic di-block copolymer under pressure - Carbon dioxide or mercury as pressure medium

The present work deals with the interactions between carbon dioxide, used as pressure medium, either in the gas state (GCO(2)) or in the supercritical state (SCCO2) and amphiphilic di-block copolymers PEOm-b-PMA(Az)(n). The effect of pressure on the isotropic transition of the PEOm-b-PMA(Az)(n) copolymer was investigated using scanning transitiometry (ST). The experimental results were compared with those measured when using 'relatively inert' mercury (Hg) as pressure medium. Morphological observation of a PEOm-b-PMA(Az)(n) thin film submitted to SCCO2 was performed by atomic force microscopy (AFM) to investigate the nano-structure organization. These results indicate the possibility of modifying the nano-structure in a specific way depending on the CO2 physical state.