Hydrophilic and hydrophobic aerosil particles immersed in S-(+)-[4-(2-methylbutyl) phenyl 4-$n$-octylbiphenyl-4-carboxylate] or [$p$-($n$-decyloxy) benzylidene-$p$-amino-(2-methylbutyl) cinnamate] compound have been studied by employing x-ray diffraction. The aerosil-induced relative layer compression $\Delta d$ has been measured in the smectic $A$ phase as a function of aerosil concentration $x$. $\Delta d\left(x\right)$ is shown to sensitively monitor the intermediate-rigid transition of the adaptive aerosil network. The dominant mechanism leading to the $\Delta d\left(x\right)$ profiles is the global establishment of the aerosil-induced molecular tilt in the smectic $A$ phase.

• Received 31 October 2005

DOI:https://doi.org/10.1103/PhysRevE.73.031707