Thermally-regulated molecular selectivity of organosilica sol-gels

The feasibility of using temperature as a control mechanism for altering the selectivity of organosilica sol-gels for a specific molecule is demonstrated in this communication. The porous organosilica sol-gels act as reversible thermoresponsive materials which become hydrophobic at higher temperature and hydrophilic at lower temperature. When exposed to a mixture of molecules, the gels selectively intake the more hydrophobic species at higher temperature. A particularly remarkable feature of these gels is their ability to preferentially sequester the hydrophobic molecule at high temperature and the hydrophilic species at low temperature. Finally, these gels selectively intake hydrophobic molecules at high temperature and then preferentially release them when the temperature is lowered. Copyright © 2003 American Chemical Society.