Bimodal Size Distribution of VO2 Nanoparticles in Hydrophilic Polymer Films for Temperature-Triggered Infrared Transmission Control

• Published in: ACS applied nano materials Vol. 3; no. 7; pp. 6645 - 6653
• Main Authors: Zomaya, Dicho, Xu, William Z, Grohe, Bernd, Mittler, Silvia, Charpentier, Paul A
• Format: Journal Article
• Language: English
• Published: American Chemical Society 24-07-2020
• Subjects: thermal transmission control; PMMA; hydrophobic; hydrophilic; vanadium dioxide; P4VP; dispersion
• ISSN: 2574-0970; 2574-0970
• DOI: 10.1021/acsanm.0c01072

This work reports on a synthetic approach for enhanced thermochromic polymer films delivering vanadium oxide nanoparticles (VO2 NPs) in a bimodal particle size distribution: ∼50 and ∼300 nm. Monoclinic VO2 particles are the active ingredients in polymer coatings for temperature-triggered infrared (IR) transmission control. The bimodality promoted the dispersion of VO2 nanoparticles in the hydrophilic polymer coatings poly­(4-vinylpyridine) (P4VP) and polyvinyl­pyrrolidone (PVP). The superior dispersion enhanced the coating’s IR switching efficiency (ΔT IR) (i.e., transmission change due to the temperature-triggered phase transition). The effects of VO2 NP concentration in the polymers as well as coating thickness on the optical properties of the coatings were systematically evaluated. The resulting VO2(M)/P4VP films exhibited good infrared (IR) transmission switching, ΔT IR@2500nm, of 47% with an adequate visible transmittance, T vis@680nm, of 41%. Hydrophobic VO2/poly­(methyl methacrylate) (PMMA) films gave a ΔT IR@2500nm of 30% and a T vis@680nm of 29%. The superb performance of the VO2(M)/P4VP coating is ascribed to the uniform dispersion of VO2(M) nanoparticles within the matrix.