Polymer-modified cement-based coating containing organic-inorganic silicons modified polyacrylate emulsion: Performance and mechanisms

How to simply and effectively improve the mechanical properties and UV resistance of polymer-modified cement-based coatings is the key to expand its application field. In this study, a novel type of polyacrylate (M-PA) emulsion modified by polydimethylsiloxane (PDMS), colloidal nano-silica (CNS), and 3-Glycidyloxypropyltrimethoxysilane (KH-560) was prepared based on the response surface methodology (RSM) to achieve composition optimization. In addition, the effect of M-PA emulsion on the mechanical properties, impermeability, microstructure, and UV resistance was comprehensively studied. The research results demonstrated that the tensile strength and hydrophobicity of M-PA emulsion film were the best when the content of CNS, PDMS and KH560 was 16–17%, 6–7% and 0.075–0.12%. The reason can be attributed to the chemical combination of modifier and the formation of 'Si-O-Si' of three-dimensional network structure in M-PA emulsion. In comparison with a coating containing unmodified PA emulsion, the bond and tensile strength of M-PA modified samples were increased by 29% and 43%, respectively, while the water absorption was reduced by 28% due to the refinement of microstructure. As a result, the hydrophobic film of the modified coating was still intact after UV-aging for 1000 h.