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Photonic Gels (photonic + gel)

Distribution by Scientific Domains
Polymers and Materials Science100%

Selected Abstracts

Control of Optical Hysteresis in Block Copolymer Photonic Gels: A Step Towards Wet Photonic Memory Films

ADVANCED FUNCTIONAL MATERIALS, Issue 11 2010
Eunjoo Kim
Abstract Polystyrene- block -poly(2-vinyl pyridine) (PS- b -P2VP) block copolymer photonic gels are fabricated that exhibit controllable optical hysteresis in response to a cyclic pH sweep. The optical hysteresis is tuned by controlling the ion-pairing affinity between various anions and the protonated pyridinium ions on the P2VP block, which is highly dependent on the hydration energy of the ions, the dielectric constant of the solvent, and the ionic strength of the medium. The pH coercivity defining the magnitude of hysteresis of the photonic gels could be varied from 0.26 to 7.4. Photonic gel films with strong optical hysteresis can serve as wet photonic memory films where information can be cyclically recorded and erased at least 15 times and maintained for at least 96,h. The memory colors can be further tuned by selection of the copolymer molecular weight. [source]

Tunable Full-Color Pixels: Bioinspired Electrochemically Tunable Block Copolymer Full Color Pixels (Adv. Mater.

ADVANCED MATERIALS, Issue 30 2009
30/2009)
The cover represents 1D periodic lamellar block-copolymer photonic gels swollen with methanol and acetic acid and laser-etched to form the outline of a squid. Edwin Thomas and co-workers show on p. 3078 that the gel displays different colors in different areas due to the variation of the relative amounts of the two solvents. In nature, real cephalopods (squid, octopus, and cuttlefish) have the ability to change the chemical environment around their one-dimensional reflectors thus creating naturally tunable photonic elements. [source]