Abstract
ABSTRACTTwo-step acid/base (B2) and acid/acid (A2) catalyzed silica gels have been aged in ethanol or water baths followed by various aprotic solvents with a range of surface tensions. The physical and chemical structures of xerogels dried from these aprotic solvents were studied by a series of techniques (nitrogen adsorption, elemental analysis, TGA, SAXS)and compared to the corresponding structures of low temperature (CO2) and high temperature (ethanol) aerogels. The aprotic solvents help to isolate the effects of pore fluid surface tension during drying since they do not react with the gel surface. B2 xerogels showed a linear decrease in surface area with increasing surface tension. Pore volume and pore size followed a similar trend. Micropore analysis on A2 xerogels showed an increase in micropore volume and surface area with increase in surface tension, whereas total surface area and pore volume showed an opposite trend. Thus, by varying surface tension and aging, one is able to independently control surface area, pore volume, and pore size.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
