Small-angle neutron scattering experiments investigating the structure of porous Vycor glass are reported. The long-wave-length behavior ($0.004{\AA }^{-1\mathrm{}}\le q\le 0.025{\AA }^{-1\mathrm{}}$) of the measured structure factor $S\left(q\right)\mathrm{}$ is in good agreement with Cahn's prediction for spinodal decomposition. The high-$q$ data do not conclusively establish whether the internal surfaces are fractally rough over the length scales probed. Experiments on Vycor contrasted with protonated and deuterated cyclohexane reveal local composition gradients within the glass.

• Received 8 May 1987

DOI:https://doi.org/10.1103/PhysRevA.36.2991