Provided is a pore-filling method for protecting the pores of a porous material. The method, which is performed using a modified i-CVD technique, involves filling the pores of a porous material with a gas phase monomer within a pressure chamber and subsequently polymerizing the monomer, both within the pores and on the surface of the material as an overburden. The method is solvent-free and can fill and protect pores of any size of any material.