The polystyrene acrylate (PSA) coating and polysiloxane coatings can protect the durability of cementitious materials through surface barrier and internal hydrophobicity, respectively. However, their composite coating presents a challenge due to the significant difference in molecular structure, molecular polarity, and thermodynamic properties, leading to poor interfacial compatibility. This paper presents a novel multi-component interpenetrating polymer network (IPN) based on the ‘host - guest molecular structure’ theory, which consists of cross-linked PSA as the main molecule and polysiloxane as the guest molecule, interfacially regulated by functionalized nanoparticles. The IPN composite coatings with high microphase separation properties enable dual synergistic protection of the durability of cementitious materials. The IPN emulsions synthesized increased the proportion of harmless pores within the cementitious materials to over 88.3 %. Additionally, they decreased the static capillary water absorption of concrete by over 94.06 % and effectively inhibited the formation of corrosion products, including Friedel's salt, gypsum, ettringite, and CaCO. The adhesion strength of the IPN coating was also improved to 2.7 MPa, and its thermal expansion coefficient was limited to within 5.5 × 10/K. Moreover, the modified IPN coating contains numerous strong hydrogen bonds and interwoven molecular networks. These features enable stable deformation recovery and surface shielding of cracked concrete.