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BIO-inspired NAcre-like materials FOR the next generation of conservation treatments in stone ART works

Periodic Reporting for period 1 - BIONA4ART (BIO-inspired NAcre-like materials FOR the next generation of conservation treatments in stone ART works)

Período documentado: 2019-07-01 hasta 2021-06-30

Cultural heritage is an incalculable and integral legacy to our future. Its loss would have catastrophic consequences, both in terms of culture (loss of identity) and economy (considering cultural heritage-related tourism and activities). Thereby, the obligation to preserve and provide access to it is an absolute necessity, becoming a vital challenge for society. Some of the most famous examples of this cultural heritage are composed of stone. This stone heritage is continuously suffering from weathering processes due to their interaction with the environment, an issue that has become urgent since the increase of natural decay caused by climate change and the impact of atmospheric pollution. The intrinsic challenge with this conservation problem is that there are currently no durable treatments available for the preservation of stone in aggressive environments. As a result, there is an emerging priority associated with the development of new conservation-restoration treatments able to overcome the limitations in terms of efficacy, compatibility and/or durability of the available treatments. Inspired by the fascinating structure of the mother-of-pearl, which provides impressive mechanical properties with high fracture toughness to shells, during this MSCA fellowship, the goal is to design and develop a novel multilayered coating for the preservation of stone heritage. The overall objective is to formulate and fabricate a sequential layer-by-layer deposition of continuous mineralized layers and a rapid assembly between then and to test the idea that these coatings would provide an unusual combination of low density, strength, and high resistance against fracture to stone materials.
To date, this project achieved the development of a novel nacre-like organic-inorganic multilayered coating for stone heritage preservation. An extensive characterization of the role of the organic substrate in templating the structure of mineralized layers, as well as the use of soluble additives (including small inorganic ions and large organic molecules, such as proteins and polymers) has been carried out so as to obtain structural control of the layers, including their orientation, morphology, and hierarchical structure. Moreover, the application of these nacre-like coatings as a new surface treatment has been studied on marble lithotypes, demonstrating the replication of biomineralization in natural systems by using polycarboxylates-induced calcite mineralization over stone. Because the fracture toughness as a new surface treatment and mechanical properties of materials can be dramatically enhanced on the nanoscale, it is envisaged that these coatings will have a superior resistance against fracture over conventional treatments, resulting in improved functional performance and more durable stone conservation treatments.

Dissemination of results to date has been achieved via two international conferences (for one as an invited speaker), an online workshop (as an invited speaker), and two invited academic seminars. The fellow has also participated in public engagement (e.g. "European Science Slam!”) and pitch events to industry, policymakers and the general public (e.g. “Science is Wonderful!” exhibition). Furthermore, two manuscripts are under preparation, which will report the final results from this project. These publications will acknowledge all European Commission funding and will comply with EU open access policies.
The investigations included to the date in the BIONA4ART project have contributed to the knowledge and development of a nacre-like multilayered coating with controllable composition, structure and properties for the protection of stone materials. By controlling the reaction conditions, and in particular the presence of polycarboxylates a layered hybrid coating can be generated with a composition very similar to that of nacre. In addition, the level of control over the locations of mineralization sites can even be used to generate more complex patterns in hybrid layers. Therefore, the knowledge acquired in this research project has a great impact on the generation of new multi-layered nacre-like coatings with highly targeted final properties. This bioinspired mineralization strategy is also of interest to a wide range of materials with potential applications beyond cultural heritage such as building industries.
Top-view SEM image of mineralized stone surface.