The comparison of high-resolution TEM images of KPHI and KPHI-Si shows that the silica is not only homogeneously distributed on the surface of the PHI particles, but is also present in the form of fibers wrapped around the PHI particles (See Supplementary Information Figure ). Such fiber morphology is expected to be produced by the applied sol-gel technique that is known to favour the formation of rodshaped silica particles. In line with the SEM results, the BET specific surface area of PHI is more than doubled after the modification of the parent material with silica (Table ). This effect can be due to the better separation of the PHI particles within the material yielding more exposed surface and/or to the deposition of high surface area silica particles over PHI. The increased specific surface area is observed for all modified samples with an exception of KPHI-OTS, where a longer alkyl chain of the grafted alkylsilane could cause the blockage of pores (Table ).