Photochromic thermoplastics doped with nanostructured tungsten trioxideElectronic supplementary information (ESI) available. See DOI: 10.1039/c8nj01531g

Tungsten trioxide (WO 3 )-based photochromic materials endowed with unique functionalities have aroused multidisciplinary interest from chemists, physicists and materials scientists. In this paper, a series of photochromic materials were successfully fabricated by blending WO 3 nanocrystals with different morphologies (nanosheet, nanorod, and amorphous) into a polymer matrix composed of a poly(methyl methacrylate- co -butyl acrylate) P(MMA- co -BA) random copolymer. The systematic investigations of these hybrid composites revealed that their mechanical and photochromic properties strongly depended on the morphology, size and surface polarity of the WO 3 compounds, and the loading level of WO 3 in the resultant materials. Specifically, the surface polarity of WO 3 dominated the compatibility of this inorganic filler with the polymeric phase. A low concentration (0.5% by weight) of WO 3 nanorods could effectively reinforce the polymer continuum. On the other hand, the WO 3 nanosheets tended to deteriorate the mechanical performance of the composites. Notably, the concentration and morphology of WO 3 heavily influenced the photochromic behavior of the prepared materials, while the surface polarity of WO 3 did not play a critical role here. This work elucidates a detailed map for designing and constructing high performance WO 3 /polymer composite materials for photochromic applications. Photochromic materials were successfully fabricated by blending WO 3 nanocrystals with different morphologies (nanosheet, nanorod, and amorphous) into a polymer matrix.