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Solubility of CO2-philic polyhedral oligomeric silsesquioxanes in supercritical carbon dioxide

Demirtaş, Cansu
Polyhedral oligomeric silsesquioxanes (POSS) with different functional groups and carbon dioxide (CO2) binary systems’ phase behavior have been studied in a high- pressure visible cell to contribute to the development of environmentally friendly processes of POSS with supercritical carbon dioxide. POSS can show different hybrid material properties due to its functional groups attached to its cage structure. Supercritical carbon dioxide, which is referred as an environmentally friendly solvent, can exhibit specific interactions such as Lewis acid-base interactions or weak hydrogen bonding due to its quadrupole moment, and form single phase solutions with various materials. The studied POSS structures, which can form homogenous solutions with CO2, include octatrimethylsiloxy, methacryl, isooctyl, octaisobutyl, and trifluoropropyl POSS. Octatrimethylsiloxy POSS-CO2 system has been studied for the first time, while the other POSS-CO2 phase behavior studies have been conducted at different temperature ranges than those studied previously. Experimental data have been correlated using semi-empirical density-based models which are Mendez-Santiago and Teja (MST), Chrastil, Bartle, Chrastil Modified Wang (C-W), del Valle and Aguilera (del Valle) and Kumar and Johnston (K-J).