Design and characterization of a SiO2-TiO2 coating containing organic and inorganic thermochromic pigments and optimized with TiO2-P25 for improved long-term performance in energy-efficient roofing

Autor(es)

Hidalgo-Araujo, Ana Carolina ; Salomao, Rafael ; Berardi, Umberto ; Dornelles, Kelen Almeida

• Tipo de documento: Artigo Científico
• Fonte: SOLAR ENERGY MATERIALS AND SOLAR CELLS; v. 289, p. 15-pg., 2025-04-21.

Resumo

This experimental study focuses on developing and characterizing thermochromic roof coatings contributing to energy-efficient building solutions. It addresses two key challenges: the limited durability of organic thermochromic pigments and the lack of research on applying thermochromic materials to opaque surfaces, especially inorganic pigments. Two coatings were developed: whereas the first contained a microencapsulated organic pigment (TC), the second used inorganic vanadium dioxide-based particles (VO2-W). Both were applied to ceramic and fiber cement tiles with a formulation that combined a binder (colloidal silica, SiO2) and titanium dioxide (TiO2) to improve durability. The novelty of the paper was the addition of a TiO2-P25 protective layer that retarded photodegradation and improved the long-term stability of the TC pigment. Coating components were evaluated using differential scanning calorimetry, solar reflectance, scanning electron microscopy, infrared spectroscopy, and X-ray diffraction. Coating performance was assessed regarding solar reflectance, thermal emissivity, and hydrophobicity. The results showed that the TC coating responded dynamically to temperature changes, indicating potential for improving buildings' thermal comfort and energy efficiency. On the other hand, the VO2-W coating showed limited performance in the infrared. In particular, TC coatings with TiO2-P25 exhibited 57 % less degradation below the transition temperature and 37 % less when heated. The main finding of this study demonstrated that TiO2-P25 significantly improved the durability of organic thermochromic coatings, offering a promising strategy to reduce the need for artificial cooling, reduce CO2 emissions, and mitigate the urban heat-island effect. The results also addressed critical gaps in the durability of organic thermochromic pigments and the application of inorganic pigments to opaque surfaces. (AU)

• Processo FAPESP: 10/19274-5 - Nova rota de sínteses de hidrotalcita (Mg6Al2(OH)16CO3.4H2O) a partir de suspensões aquosas de óxido de magnésio (MgO) e hidróxido de alumínio (Al(OH)3) e sua utilização em cerâmicas porosas para isolamento térmico em alta temperatura
• Beneficiário: Rafael Salomão
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores
• Processo FAPESP: 22/03655-7 - Redução de perdas energéticas em processos industriais com isolamento térmico de alta eficiência usando revestimentos moldáveis de silicato de cálcio microporoso produzido a partir de elementos de biomassa: cascas de ovos e cinzas de cascas de arroz
• Beneficiário: Rafael Salomão
• Modalidade de apoio: Auxílio à Pesquisa - Programa BIOEN - Regular
• Processo FAPESP: 24/00850-9 - Caracterização e simulação termoenergética de telhas multifuncionais
• Beneficiário: Ana Carolina Hidalgo Araujo
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Doutorado
• Processo FAPESP: 22/14074-5 - Telhas termocrômicas e autolimpantes: uma cobertura adaptativa e resiliente
• Beneficiário: Ana Carolina Hidalgo Araujo
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 24/10060-5 - REVESTIMENTOS PARA O ENVELOPE CONSTRUTIVO E A AVALIAÇÃO DA DEGRADAÇÃO DA ABSORTÂNCIA À RADIAÇÃO SOLAR: proposta de um método nacional de ensaio acelerado
• Beneficiário: Kelen Almeida Dornelles
• Modalidade de apoio: Auxílio à Pesquisa - Regular