Photochromic Polyurethanes Showing a Strong Change of Transparency and Refractive Index

Oggioni, Luca; Toccafondi, Chiara; Pariani, Giorgio; Colella, Letizia; Canepa, M.; Bertarelli, Chiara; Bianco, Andrea

doi:10.3390/polym9090462

Cited by 12 publications

(15 citation statements)

References 19 publications

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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%

Synthesis of polydithiourethanes and their thermal, optical, and mechanical properties originated from monomers structure

Yoshida¹,

Endō²

2018

J. Polym. Sci. Part A: Polym. Chem.

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Polyaddition of various diisothiocyanates and dithiols was achieved with triethylamine in dimethylformamide at 25 °C for 12 h under nitrogen, and then the corresponding polydithiourethanes (PDTUs) were obtained with high yield and molecular weight without depending on the monomer structures, although the dithiol monomer of the low nucleophilicity was unsuitable for polyaddition in this system. The chemical and physical properties of the obtained PDTUs such as solvent solubility, glass transition temperature, thermal stability, transparency, refractive index, and tensile strength, were analyzed in detail by gel permeation chromatography, nuclear magnetic resonance, Fourier transform infrared–attenuated total reflection, ultraviolet–visible, differential scanning calorimetry, thermogravimetric analysis, and tensile testing measurements. These results proved that PDTUs and their cast films having the aliphatic diisothiocyanate and dithiol moieties exhibited excellent chemical and physical properties compared to that of the aromatic PDTUs. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 2255–2262

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Section: Resultsmentioning

confidence: 97%

Synthesis of polydithiourethanes and their thermal, optical, and mechanical properties originated from monomers structure

Yoshida¹,

Endō²

2018

J. Polym. Sci. Part A: Polym. Chem.

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“…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%

Adaptable Microcontact Printing via Photochromic Optical‐Saturable Lithography

Pariani

Castagna

Oggioni

et al. 2018

Adv Materials Technologies

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be applied with light-sensitive compounds or biological agents that are not resistant to UV illumination.Soft-lithography [5] and in particular microcontact printing (µCP), [6] was acknowledged as a great innovation in the field of microelectronics for surface chemical functionalization and patterning of a wide range of materials with satisfactory spatial resolutions. [7,8] Soft-lithography uses a master to mold a soft polymer. In particular, in µCP a soft polymer stamp, like polydimethylsiloxane (PDMS) or some other polymers, [9] is usually employed and "inked" with a desired molecule which is then transferred onto a substrate by contact. The relief of the elastomeric stamp, usually in the micrometric-scale, is replicated over the substrate. PDMS is a soft polymer, which allows for a conformal contact between the stamp and the surface to be functionalized. Generally, a good replica between the mold pattern and the printed one is obtained. [5,10,11] However, the elastomeric nature of the polymer stamp can also cause some deformation in the pattern relief due to contact pressure. Few failure events can occur depending on the dimensional ratio of some features to be printed, as for example collapse, buckling, or sagging of the reliefs. [12] Worth noting, a PDMS stamp can last more than 100 prints over a period of several months without noticeable degradation. [4] Moreover, in case of patterning of biomolecules, a complete transfer of ink from the stamp to the substrate was observed within a few seconds of contact time. [13] The surface patterning by microcontact printing prevents the use of toxic and aggressive chemicals onto the bioactive surface to be patterned, since PDMS is biocompatible. Good control over surface wettability patterning, [14] printing localization, [15] and the deposition of bioactive molecules, [16] DNA, [17,18] cells, [4] and proteins [19,20] have been demonstrated. Patterning of bacteria [21] or neurons [22] has also been reported by microcontact printing of antibody and proteins, respectively.In this biotechnology framework, the possibility to pattern a surface with a customizable shape in the range of few micrometers down to hundreds of nanometer over millimeter size region is of great interest. For example, nanopatterned surfaces can provide better cell-material interaction for cell engineering, and they can also be differentiated by additive technology. [23] Moreover, in microfluidic bioassays, the sensitivity of the test relies on the biofunctionalization and the possibility to miniaturize the patterned area with various biomarkers within a single device. [24] Patterning by soft lithography replica molding was reported on photoinduced surface-relief-gratings A versatile and easily customizable mold platform for the microcontact printing of 1D and 2D patterns of dyes is developed. The mold is obtained by optical-saturable lithography, which is optimized to give a fast process on millimeter size areas. Supported by a kinetic and an electro-magnetic model, 1D and 2D patterns are designed a...

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“…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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Holography with Photochromic Diarylethenes

et al. 2019

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Photochromic materials are attractive for the development of holograms for different reasons: they show a modulation of the complex refractive index, meaning they are suitable for both amplitude and phase holograms; they are self-developing materials, which do not require any chemical process after the light exposure to obtain the final hologram; the holograms are rewritable, making the system a convenient reconfigurable platform for these types of diffractive elements. In this paper, we will show the features of photochromic materials, in particular diarylethenes in terms of the modulation of a transparency and refractive index, which are mandatory for their use in holography. Moreover, we report on the strategies used to write binary and grayscale holograms and their achieved results. The outcomes are general, and they can be further applied to other classes of photochromic materials in order to optimize the system for achieving high efficiency and high fidelity holograms.

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Photochromic Polyurethanes Showing a Strong Change of Transparency and Refractive Index

Cited by 12 publications

References 19 publications

Synthesis of polydithiourethanes and their thermal, optical, and mechanical properties originated from monomers structure

Synthesis of polydithiourethanes and their thermal, optical, and mechanical properties originated from monomers structure

Adaptable Microcontact Printing via Photochromic Optical‐Saturable Lithography

Holography with Photochromic Diarylethenes

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