Structure design of double-pore silica and its application to HPLC

Utilizing the concurrence of polymerization-induced phase separation and so l-gel transition in the hydrolytic polycondensation of alkoxysilanes, a wel l-defined macroporous structure is formed in a monolithic wet gel. By excha nging the fluid phase of the wet gel with an appropriate external solution, the nanometer-range structure of the wet gel can be reorganized into struc tures with larger median pore size essentially without affecting the macrop orous framework. The double-pore structure thus prepared is characterized b y open pores distributed in discrete size ranges of micrometers and nanomet ers. A new type of chromatographic column (silica rod) has been developed u sing monolithic double-pore silica instead of packed spherical gel particle s. Typical silica rod columns had significantly reduced pressure drops and improved analytical efficiencies which do not deteriorate even at higher sa mple flow rates, both arising from a greater macropore volume than particle packed columns.