Self-assembled polymeric solid films with temperature-induced large and reversible photonic-bandgap switching.
In aqueous solutions the response of polymers and biological matter to external conditions, such as temperature and pH, is typically based on the hydrophobic/hydrophilic balance and its effects on the polymer conformation. In the solid state, related concepts using competing interactions could allow novel functions. In this work we demonstrate that polymeric self-assembly, reversibility of hydrogen bonding, and polymer-additive phase behaviour allow temperature response in the solid state with large and reversible switching of an optical bandgap. A complex of polystyrene-block-poly(4-vinylpyridinium methanesulphonate) and 3-n-pentadecylphenol leads to the supramolecular comb-shaped architecture with a particularly long lamellar period. The sample is green at room temperature, as an incomplete photonic bandgap due to a dielectric reflector is formed. On heating, hydrogen bonds are broken and 3-n-pentadecylphenol additionally becomes soluble in polystyrene, leading to a sharp and reversible transition at approximately 125 degrees C to uncoloured material due to collapse of the long period. This encourages further developments, for example, for functional coatings or sensors in the solid state.
Valkama
Sami
S
Department of Engineering Physics and Mathematics and Center for New Materials, Helsinki University of Technology, PO Box 2200, FIN-02015 HUT, Espoo, Finland.
Kosonen
Harri
H
Ruokolainen
Janne
J
Haatainen
Tomi
T
Torkkeli
Mika
M
Serimaa
Ritva
R
Ten Brinke
Gerrit
G
Ikkala
Olli
O
D003460:Crystallization / Q000295:instrumentation / Q000379:methods*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008027:Light; D008420:Manufactured Materials; D008422:Materials Testing; D008567:Membranes, Artificial; D055095:Optics and Photonics / Q000295:instrumentation*; D010777:Photochemistry / Q000295:instrumentation* / Q000379:methods; D011108:Polymers / Q000737:chemistry* / Q000528:radiation effects; D013696:Temperature
D008567:Membranes, Artificial; D011108:Polymers