TY - JOUR
T1 - Solvatochromism based on structural color
T2 - Smart polymer composites for sensing and security
AU - Dong, Xu
AU - Wu, Pan
AU - Schaefer, Christian G.
AU - Zhang, Liwu
AU - Finlayson, Christopher
AU - Wang, Changchun
N1 - Publisher Copyright:
© 2018 Elsevier Ltd
PY - 2018/12/15
Y1 - 2018/12/15
N2 - We report a convenient and scalable strategy to achieve large-area transparent photonic crystal (TPC) films that can be fully reversibly switched between an initial transparent state and a structurally-colored state. This photonic material is based on an ordered colloidal crystal structure of polymer core-shell particles with an engineered refractive index balance of the core and the shell components. Highly transparent viscoelastic quasi-solid films are created that can be spatially UV-cross-linked, giving invisible encrypted photonic patterns with different solvent response compared to non-cross-linked regions, which appear after immersion in solvent media, thus demonstrating clear and fully reversible/switchable solvatochromic properties. Our intuitive simulation models demonstrate how the emergence of structural color occurs due to increasing refractive-index contrast, whereas wavelength shifting originates from commensurate solvent swelling of the shell medium. In addition to the very clear revelation of optical patterns (large fractional changes in reflectance, from transparency to a resonant reflectivity of ~10%), these materials and thin-film generation methods are inherently scalable, robust and versatile. The demonstrated stimuli-responsive photonic films may thus give rise to new practicable applications in the fields of environmental sensing and product security
AB - We report a convenient and scalable strategy to achieve large-area transparent photonic crystal (TPC) films that can be fully reversibly switched between an initial transparent state and a structurally-colored state. This photonic material is based on an ordered colloidal crystal structure of polymer core-shell particles with an engineered refractive index balance of the core and the shell components. Highly transparent viscoelastic quasi-solid films are created that can be spatially UV-cross-linked, giving invisible encrypted photonic patterns with different solvent response compared to non-cross-linked regions, which appear after immersion in solvent media, thus demonstrating clear and fully reversible/switchable solvatochromic properties. Our intuitive simulation models demonstrate how the emergence of structural color occurs due to increasing refractive-index contrast, whereas wavelength shifting originates from commensurate solvent swelling of the shell medium. In addition to the very clear revelation of optical patterns (large fractional changes in reflectance, from transparency to a resonant reflectivity of ~10%), these materials and thin-film generation methods are inherently scalable, robust and versatile. The demonstrated stimuli-responsive photonic films may thus give rise to new practicable applications in the fields of environmental sensing and product security
KW - Core-shell particles
KW - Photonic crystals
KW - Polymer composites
KW - Stimuli-responsiveness
KW - Structural colors
UR - http://www.scopus.com/inward/record.url?scp=85053781255&partnerID=8YFLogxK
U2 - 10.1016/j.matdes.2018.09.026
DO - 10.1016/j.matdes.2018.09.026
M3 - Article
SN - 0261-3069
VL - 160
SP - 417
EP - 426
JO - Materials and Design
JF - Materials and Design
ER -