Hybrids of CNTs and acrylic emulsion for the consolidation of wall paintings

Acrylic resin Primal^® AC 33 is a common consolidant for wall paintings in a large scale. However, some disadvantages are encountered, such as low glass transition temperature (T_g), unwanted hygroscopicity, and surface gloss when applying it on wall paintings. To address these issues, the hybrids of the gum arabic treated single-walled carbon nanotubes (SWCNTs) and the Primal^® AC 33 were prepared with a different weight fraction of SWCNTs ranging from 0.005% to 0.05% via solution blending. The morphology, chemical, thermal, mechanical, and optical properties of the hybrids were systematically investigated by various characterization methods. The results show that the T_g, the hardness, and the adhesion of the hybrid films are increased with the presence of SWCNTs, while the transparency and the gloss value of the films in the visible light range decrease simultaneously compared with the pristine AC 33 film. When the hybrid solutions were applied on simulating wall painting plaster samples, the evaluation data suggest that the hybrids with the SWCNT concentration not exceeding 0.025 wt% in AC 33 can be potentially used in the consolidation of the surface layer of wall paintings. The hybrids with a higher SWCNT concentration play a positive role in the consolidation of the ground layer of wall paintings. Our work opens a new insight for enhancing the properties of a consolidant for wall paintings by introducing SWCNTs.