2017
DOI: 10.3390/polym9090462
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Photochromic Polyurethanes Showing a Strong Change of Transparency and Refractive Index

Abstract: Photochromic polymers have been studied as rewritable systems for optical elements with tunable transparency in the visible and refractive index in the NIR. Six diarylethene monomers have been synthesized to give thin films of photochromic polyurethanes. The absorption properties of the monomers in solution and of the corresponding polymeric films have been evaluated showing that a transparency contrast in the visible spectrum of the order of 10 3 can be obtained by a suitable choice of the chemical structure … Show more

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Cited by 12 publications
(15 citation statements)
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“…The refractive index of PDTU films and the sulfur content in PDTUs were also summarized in Table . The refractive index of PDTU films exhibited more than 1.650, meaning the high refractive index compared to that of polyurethane and polythiourethane having the similar structures . In general, the refractive index increases with increasing of the atomic and molecular refraction such as sulfur, halogen, and aromatic substance .…”
Section: Resultsmentioning
confidence: 97%
“…The refractive index of PDTU films and the sulfur content in PDTUs were also summarized in Table . The refractive index of PDTU films exhibited more than 1.650, meaning the high refractive index compared to that of polyurethane and polythiourethane having the similar structures . In general, the refractive index increases with increasing of the atomic and molecular refraction such as sulfur, halogen, and aromatic substance .…”
Section: Resultsmentioning
confidence: 97%
“…In order to spin cast the photoresist film on top of the photochromic layer, the latter must be solvent resistant to prevent its damaging or thinning when the photoresist is deposited. For this reason, as photochromic layer we considered a main‐chain polymer belonging to the class of polyurethanes, which shows large absorbance also for small film thicknesses. The polymer is based on the diarylethene derivative 1,2‐bis‐[5‐(p‐methoxy‐m‐hydroxymethyl)phenyl‐3‐thienyl]perfluorocyclopentene (see Scheme ) for its suitable absorption properties in the region of interest, and it is cross‐linked to make the photochromic layer solvent‐resistant for the following photoresist deposition.…”
Section: Approach and Methodsmentioning
confidence: 99%
“…Finally, the relationship between εvis and λ VIS is highlighted (Figure 6c), since the behavior of the photochromic molecules in the visible (i.e., the contrast) is relevant for the development of amplitude holograms. The overall evidence is that the longer the wavelength of the peak, the higher its absorption intensity [49], which is a common trend in conjugated molecules [50]. However, the presence of withdrawing groups (e.g., compounds 9 and 10 ) decreases the absorption coefficient, whereas donor groups lead to higher absorbance (compounds 4 – 9 ).…”
Section: Diarylethenes: Properties Modulationmentioning
confidence: 99%
“…Consequently, the modulation of the refractive index will benefit from this effect and it increases with the frequency too [57]. This feature has been recently highlighted [49] in a series of diarylethene based polyurethanes, where a clear positive trend existed between the Δn and the absorption wavelength of the colored form.…”
Section: Diarylethenes: Properties Modulationmentioning
confidence: 99%
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