A diblock copolymer brush consisting of poly-(methyl acrylate)-block-poly(pentafluoropropyl acrylate). (Si/SiO2//PMA-b-PPFA) was synthesized on a porous silica substrate. The brush was exposed to selective solvents, as well as thermal treatments, to induce a surface rearrangement. The rearrangement resulted in the selective loss or creation of an ultrahydrophobic layer by location of the fluoropolymer segment. This work demonstrates that surface rearrangement observed on flat surfaces can be transferred to porous substrates.