A sustainable approach to the conservation of bronzes artworks by smart nanostructured coatings

Corrosion of metallic artifacts is one of the important issues in the preservation and conservation of ancient artworks. The widespread use of hazardous materials (1-H-Benzotriazole, BTA) and processes used at present for conservation of bronze artifacts should be replaced by safe and environmental friendly approaches, given the increasing importance of environmental protection and preserving the health of conservation professionals. In order to overcome BTA toxicity and to develop new and safe protection systems as alternative choices for conservation/restoration professionals, halloysite nanocontainers of corrosion inhibitors (HNT/BTA) were synthesized and incorporated into a hydroxypropylcellulose matrix (KLU/HNT/BTA) and tested as nanostructured films on bronze supports. In this paper we present the surface investigation of the films performed by X-Ray photoelectron spectroscopy (XPS) both before and after a corrosive attack in a 3 wt.% NaCl solution. Results showed that both HNT/BTA and KLU/HNT/BTA films can be efficiently used as transparent bronze corrosion inhibitor coatings. Furthermore, the KLU/HNT/BTA coating exhibited a "self-healing" behavior, allowing a selective release of BTA during the corrosion process induced by chlorides, as well as a protection barrier effect due to the organic matrix.