Diarylethene-based photochromic polyurethanes for multistate optical memories

Abstract

Photochromic polyurethanes (PPUs) are synthesised by reaction between a diarylethene end-capped with hydroxyl groups and an aliphatic diisocyanate. In situ polymerisation provides amorphous films with remarkable optical properties. The possibility to vary the amount and the chemical structure of the photochromic monomer without affecting the reactivity of the polymerization allows one to tune in a wide range the optical properties of these films. In addition, different diarylethenes can be mixed together to give copolymers which may find application as photochromic layers for multistate optical memories. A setup for a non-destructive readout based on Raman signal is proposed

Photochromism of Diarylethene Molecules and Crystals: Memories, Switches, and Actuators

“…403 Figure 29, and readout nondestructively using a 1064 nm laser, which does not induce any photochromic reaction, as the excitation line source. The setup used for the readout is shown in Figure 30.…”

Photochromic Polyurethanes Showing a Strong Change of Transparency and Refractive Index

“…The general procedure to synthesize the diarylethene-based polyurethanes consists of the reaction between the specific photochromic monomer (in a 50% ratio on the total OH groups, which corresponds to about 40 wt % of all components), polyols, and 4,4 -diisocyanate dicyclohexylmethane (H12MDI), as described in the literature [14].…”

“…In particular, it has been shown that polyurethanes are good candidates, showing good resistance to solvents and allowing for versatile polymerization and processing. Moreover, polyurethanes (PUs), allowed for tunable properties, and high contrast of the processed films [14].…”

Photochromic materials for holography: issues and constraints

“…An interesting strategy is the development of photochromic polymers, where the active unit is directly linked to the main polymer chain [18][19][20][21][22]. In this way, the very high concentration of active units in the material generates high optical responses with very thin films (in the order of 1 μm) [22].…”