Photoinduced Refractive Index Change of Polymer Films Containing Mesoionic Sulfur‐Substituted Phenyloxatriazolones

Abstract

We measured photoinduced refractive index changes (see Figure) of polymer films containing various sulfur‐containing mesoionic compounds. PMMA films containing 30 wt.‐% of 3‐phenyl‐1,2,3,4‐thiatriazole‐5‐thione (3PTTT) showed refractive index changes of −0.036 during photoirradiation, at a wavelength far from the resonant region. An increase in the number of sulfur atoms in the mesoionic compounds doped in PMMA films resulted in the increase in refractive index changes during photoirradiation. The estimation and comparison of the changes in specific refraction and densities of the systems suggest that the change in electronic structure mainly contributes to the refractive index changes of the film in the case of 3PTTT, while the changes in both electronic structure and density equally contribute to the refractive index change in the film with 3‐phenyl‐1,2,3,4‐oxatriazole‐5‐thione (3POTT).

Effects of aryl substituents in N-acetyl-α-dehydroarylalanine naphthyl ester additive on the photoinduced refractive index change of poly(methyl methacrylate) film

“…[1][2][3] Recently, much attention has been devoted to the photochemical control of refractive indices for polymer films, owing to their potential in optical network technology. 3 Although there are extensive studies directed toward a photoinduced decrease in refractive indices for polymer films, [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] only a few attempts have been made to enhance the refractive index through photochemical transformations. 12,[20][21][22][23][24][25] For example, Langer et al 21 reported that irradiation of a polymerbearing thiocyanate pendants enhanced the refractive index (n) of the polymer by 0.031.…”

Large Photoinduced Refractive Index Increase in Polymer Films Containing Phenylazide Maintaining Their Transparency and Thermal Stability

“…On the other hands, by using irreversible photochemical reactions such as photoelimination and photopolymerization, large refractive index changes of polymer films have been realized with transparency both before and after photoirradiation in a wide visible region. [10][11][12][13][14][15][16][17][18][19] Among them, Photoelimination brings about the changes not only in electronic structure of photoreactive compounds and also in the density of the polymer films, which leads to larger refractive index changes. 16,17 The refractive indices of the photoirradiated area decreased in many cases, however, the increases in refractive index of the photoirradiated area are necessary for some applications.…”

Polymeric Mesoions: Novel Synthetic Methods, Photochemistry, and Characterization in the Solid State by Dielectric and Waveguide-Mode Spectroscopy

“…To obtain stable, easy to handle, film-forming materials, the photoreactive mesoionic group must be covalently attached to a polymer. During the last several years we have described the synthesis and polymerization behavior of various styrene substituted mesoionic 6-oxo-1,6-dihydropyrimidin-3-ium-4-olates. − Recently, different methods for the synthesis of polymerizable mesoionic methacryl derivatives have also been developed. , We also prepared polymers that are based on phenols as the polymerizable group or polycondensates bearing mesoionic groups in the main chain. , An alternative method is to modify technical polymers with dispersed crystals of photosensitive mesoions …”

“…For the estimation of changes in the physical properties by irradiation, different methods have been developed. For example, waveguide-mode spectroscopy can be used to determine changes in the refractive index and film thickness of spin-coated polymer films. ,, Other methods involve changes in the solubility or spectroscopic characteristics. , …”