High-resolution x-ray scattering studies of the nonpolar thermotropic liquid crystal 4-$n$-pentylphenylthiol-4′-$n$-octyloxybenzoate ($\overline{8}S5$) in aerosil gel nanonetworks reveal that the aerosil-induced disorder significantly alters both the nematic to smectic-$A$ and smectic-$A$ to smectic-$C$ phase transitions. The limiting $\overline{8}S5$ smectic-$A$ correlation length follows a power-law dependence on the aerosil density in quantitative agreement with the limiting lengths measured previously in other smectic-$A$ liquid crystal gels. The smectic-$A$ to smectic-$C$ liquid crystalline phase transition is altered fundamentally by the presence of the aerosil gel. The onset of the smectic-$C$ phase remains relatively sharp but there is an extended coexistence region where smectic-$A$ and smectic-$C$ domains can exist.

• Received 31 October 2010

DOI:https://doi.org/10.1103/PhysRevE.84.031705