Small angle neutron scattering (SANS) has been used to study (1) the a
bility to refill the pores of a silica aerogel (rho = 0.3 g/cm(3)) wit
h water and (2) and effect of the water and the re-wetting process on
the aerosol structure on the 1 nm to 100 nm scale. A sample filled wit
h a D2O:H2O solution which was chosen tu match the scattering properti
es of silica shows no scattering at length scales < 40 nm down to the
detection limit (similar to 2 nm) of the experiment. This lack of scat
tering demonstrates that the mesopores of the silica aerogel were succ
essfully filled with the contrast-matching fluid. SANS spectra for sam
ples filled with air or D2O are similar, indicating that the aerogel s
tructure as detected by this technique is not affected by the reintrod
uction of water into the pores. Results suggest that some aerogels may
be suited for applications in aqueous environments such as catalysis
or chemical sensing. (C) 1998 Elsevier Science B.V.