NATIONAL PHD IN HERITAGE SCIENCE

Thesis title: Sustainable nanohybrid materials as multifunctional treatments for Cultural Heritage

The application of sustainable materials in the conservation of Cultural Heritage is a challenging task that requires a limited use of toxic substances, both for the environment and human health, while preserving the efficacy of the treatments. Conventional restoration practices frequently rely on synthetic compounds, such as polymers and organic solvents, that could cause health problems to conservators and long-term ecological impacts on the environment. To overcome these issues, an increased emphasis has been placed on the study of renewable and biodegradable resources, including biopolymers (funori, chitosan ecc.) and natural nanofillers (such as nanoclays), bringing very promising results for the conservation community. These alternatives are not only preferable for being more sustainable, but also because they often ensure greater compatibility with the artefacts substrates and their relative constituent materials. In addition to evaluating the effectiveness of these new treatments, it is important to take into account costs, results reliability, and applicability. Among these new materials, biopolymers play an important role in many industrial sectors, such as agriculture, food packaging, medicine, construction, and textile. They are gaining ground due to their non-toxicity, biodegradability and low carbon emissions. Along with biopolymers, nanomaterials are being widely used in material science and engineering because they are low-cost, available in nature, and highly effective at improving material properties. Indeed, they are able to enhance optical, thermal, and mechanical behaviour, as well as being suitable for selective functionalization. With a particular focus on Cultural Heritage conservation, Halloysite nanotubes (HNTs) are widely employed for emulsions, gels and coatings formulation. Thus, in this research, we focused on the development of new sustainable alternative materials based on biopolymers, bio-derived active compounds, gel formulations, and nanoclays. These hybrid systems were thoroughly characterized using a range of analytical techniques, including optical and fluorescence microscopy, scanning electron microscopy (SEM), Raman and FTIR spectroscopy, thermogravimetric analysis (TGA), rheological measurements. These methods provided insights into the morphology, thermal stability, viscoelastic behaviour, and molecular interactions of the systems, both in their pristine state and after application to model substrates. Afterwards, each system was then tested on mock-ups and real artworks to evaluate the effectiveness, compatibility, and safety of the treatments under realistic conservation conditions. These application studies confirmed the performance and adaptability of the materials across different conservation scenarios. The results demonstrate the potential of these eco-designed nanohybrid materials to meet the requirements of cultural heritage conservation, offering an environmentally responsible alternative to conventional restoration practices. The outcomes of this work have been disseminated through peer-reviewed articles already published in ISI journals, with other further manuscripts currently in preparation and under submission.