Conductive fillers, such as carbon nanotubes (CNTs) with much better strength and structure, through functionalization process, can be added into building materials, such as paint, in order to enhance shielding of the electromagnetic waves. With the use of mechanical stirring, either SDS or NaDDBS surfactant is used to improve dispersion of CNTs in the paint. The SEM images indicate that adding SDS enables better dispersion of CNTs in the paint. The new dispersant, NaDDBS, can also disperse CNTs, but will reduce the shielding effect of the electromagnetic wave if the amount of dispersant is added too much in the paint. After functionalization of the CNTs with trifluoroacetic acid together with SDS or NaDDBS, the CNTs blended in the paint can enhance shielding of the electromagnetic wave.