Novel products for multilayer coating cycles used as smart strategy to increase energy efficiency and environmental sustainability of buildings: formulation, development and simulation models

Today, crude oil derivatives are worldwide used as raw materials for the synthesis of carbon-based chemicals. However, the environmental sustainability of their entire life cycles, from the extraction to the application, has been recognized as poor. For what concerns the building sector, synthetic polymers obtained from crude oil are traditionally used inside the coatings formulations. Considering the concern about their environmental impact, it is mandatory and urgent to find more environmentally friendly alternatives. Without any doubt, the most promising alternative to carbon source is biomass, either in its natural state, i.e., biopolymers, or as waste material from agriculture and the food industry. Despite the wide availability of biomass, and the large research on its extraction and modification, the production of bio-based chemicals and the related substitution of the traditional ones is still far to be obtained. Along with the impact of single compounds, another concern about building sustainability lies on the construction processes and the impact of their life cycle. For example, household heating systems mainly depend on fossil fuels and for low thermal insulation building envelopes, the energy consumption in the EU accounts for around 36 % of greenhouse gas emissions. With these premises, the present PhD Thesis foresees two different goals, namely the development of construction materials for the building sector by using biomass derivatives and recycled components to increase sustainability, and the improvement of energy efficiency for existing and new buildings by enhancing the thermal insulation properties of the building envelopes. The raw materials chosen in this project to replace some of the traditional components are alginate, a biopolymer extracted from seaweed, natural zeolite, naturally occurring porous volcanic rocks, and organic based aerogels from food waste. For what concerns alginate, the key idea is that its well-known gelling ability, so far mainly used in biomedical and food industries, can be exploited inside coatings formulations as well to improve flow properties during the storage and application phase. The role of its molecular weight, concentration and counterion type has been deeply evaluated through rheological, spectroscopic and tensile tests. According to the obtained results, it can be concluded that such a biopolymer represents a suitable bio-based thickener with an associative like character. Regarding natural zeolites and organic-based aerogels, they were investigated as a sustainable approach to achieve coating formulations with a low thermal conductivity taking inspiration from highly porous synthetic materials (e.g, synthetic zeolite and silica aerogels). In this context, natural zeolites purchased from national mines and aerogels obtained by recycling food wastes, specifically spent ground coffee and apple pomace, perfectly fit in this research. Considering their natural origin and the lack of literature, the use of these materials as thermal filler inside a coating formulation is ambitious. Moreover, their hydrophilic character does not harmonize with common water based coatings. To overcome this problem, a surface modification of both zeolites and aerogels was carried out to enhance their hydrophobic character. Thermal properties of both zeolite and aerogel-based plaster were enhanced, with resulting thermal conductivity being lower than that of a standard mineral plaster. Due to its high novelty, despite the research is still at a preliminary phase, this project can be considered an important step towards the development of coating formulations with a higher amount of bio-based or recycled components and promising thermal insulating properties