Effect of silica nanoshell on the stability and thermochromic properties of monoclinic VO2 particles dispersed in Poly(vinylbutyral) films

MIGUEL, MARÍA DE LA PAZ; PENELAS, MARÍA JAZMÍN; ARENAS, GUSTAVO FRANCISCO; HOPPE, CRISTINA ELENA; PARRA, RODRIGO; PUIG, JULIETA

Materials Today Communications

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Año: 2025 vol. 44

2352-4928

Belt-shaped particles of the metastable phase vanadium dioxide (VO2(B)) were synthesized via a hydrothermal method using ammonium metavanadate and oxalic acid. To be transformed into the thermochromic monoclinic phase (VO2(M)), the particles were annealed at 550◦C. To enhance the stability and optical properties while preventing coarsening, a SiO2 nanoshell was grown on the VO2(B) particles using a modified Stober ¨ method. This SiO2 shell protected the particles, preserving their morphology and preventing coarsening. The resulting VO2(M) particles were incorporated into composite films made from PVB, a UV-resistant polymer used in security glass. These films demonstrated excellent transparency and contrast between transmissive and reflective states, attributed to the SiO2 shell’s stabilizing effects. The SiO2-coated before the annealing treatment VO2 particles also exhibited improved chemical and thermal stability. These findings show the potentiality of SiO2-coated VO2(M), as a material to produce laminated protective glass with long-term thermochromic properties.