Topologically optimized polystyrene acrylate-polysiloxane copolymer coatings toward superior durability of cementitious materials

Cementitious materials in durability can be improved by membrane protection and osmotic hydrophobicity with Polystyrene acrylate (PSA) and polysiloxane (PSE), respectively. However, due to the significant differences in molecular structure, the fabrication of PSA- PSE composite coatings with multiple protective effects have been a thorny issue. In order to enhance the interfacial binding effect between PSA and PSE, and to solve the problem of poor stability caused by poor compatibility, this paper innovatively utilizes the topological network structure growth regulation mechanism of secondary surface functional nanoparticles to prepare PSA-PSE copolymer emulsions with highly crosslinked star and dendrimer structures, respectively, with branch grafting ratios of over 94% and semi-crystallinity of over 5.39%. As a consequence of surface treatment, numerous dense calcium-silicate crystals with low Ca/Si ratios are deposited inside the cementitious materials, decreasing the volume proportion of harmful micropores and connected capillary pores to below 10.4%. The modified copolymer coatings decrease the capillary water absorption and static permeability of concrete by over 55%, and lead to nearly 80% reduction in carbonation depth of cement hydrates, and have an adhesion strength of up to 3.3 MPa. Particularly, the proportion of ordered hydrogen bond within the composite coating reached 45.1%, demonstrating excellent reversible elastic deformation recovery performance.