Synthesis, Characterizations, and Thermochromic Properties of VO2 Particles Grafted with PSS:PEDOT,

Vanadium dioxide (VO2) particles were modified by grafting with poly(styrene sulfonate) (PSS) and poly(3,4-
ethylenedioxythiophene) (PEDOT) via surface-initiated atom transfer radical polymerization (SI-ATRP). Critical transition temperature (Tc) of the modified VO2 ranging between 77 and 79°C was obtained. After mixing with acrylic-based emulsion, dispersion of the VO2 particles in the polymer matrix was significantly improved. The visible light transmittance through the composite films above 75% was maintained if a concentration of the modified VO2 particles loaded into acrylic polymer film was no greater than 1.0 wt%. The NIR transmittance through the acrylic/VO2@PSS : PEDOT also dropped by 9-10%, compared
with that of the pure acrylic film (without any particles). Finally, glass substrates coated with the acrylic/VO2@PSS : PEDOT composite films could reduce the temperature inside a model house by 5-6°C, compared with that of the control system (pure acrylic coating film without VO2 particles). Overall, this work demonstrated that it was possible to improve the dispersion of VO2 particles in polymer films without sacrificing its NIR shielding ability by grafting the surface of VO2 particles with PSS : PEDOT chains, while providing the optimum grafting density and particle loading.