Large Photoinduced Refractive Index Change in a Polyimide Film by Charge-Transfer Complex Formation with a Polymer-Bound Phenylazide Fragment

Kashiyama, Yuuki; Jianguo, He; Machida, Shinjiro; Horie, Kazuyuki

doi:10.1002/1521-3927(200102)22:3<185::aid-marc185>3.0.co;2-c

Cited by 5 publications

(6 citation statements)

References 10 publications

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“…In general, polymer films containing a photoeliminable compound exhibit decreases in refractive index during the photoreaction as mentioned above, however the polymer films containing some azido derivatives did not decrease but increased their refractive indices by photoirradiation. 16,20 Moreover, since PAZ is volatile, we can remove unreacting PAZ from the non-irradiated area of the polymer films at a moderate condition, which gives not only large refractive index increase but also thermal stability on patterned polymer films.…”

Section: Introductionsupporting

confidence: 91%

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

Murase

Shibata

Furukawa

et al. 2003

Polym J

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ABSTRACT:We realized large photoinduced refractive index increases of poly(methyl methacrylate) (PMMA) films containing phenylazide (PAZ) through photochemical and thermal processes. The refractive index increase of the PMMA film containing 30 wt% PAZ through the processes is as much as 0.0161 with transparency in a wide visible region both before and after photoirradiation and with moderate thermal stability. These excellent performances suggest the applicability of PAZ doped PMMA films for optical devices.KEY WORDS Refractive Index Increase / Photocleavage / Phenylazide / M-line Method / Polymer Film / Poly(methyl methacrylate) (PMMA) / Nitrene / Optical Device / Organic polymers have received considerable attention as materials for opto-electronics applications because of their processability and reasonable cost performances. Some organic polymers have already been applied to optical devices, such as optical fibers, microlenses, liquid crystal display components and polymer light emitting diodes. 1, 2 The possibility of organic polymers for opto-electronics applications is not limited, and developments of organic polymers have been more and more promoted.A photochemical reaction is an important process in the fabrication of refractive index patterns in polymer films. The photochemical reaction can induce larger refractive index modulation in polymer films and the modulation remains after the photoreaction, leading to the permanent change in refractive index. Therefore, photochemically induced refractive index changes in polymer films have been attracting much attention for various applications, such as optical memories, switching devices and optical waveguides.We can use various kinds of photoreactions, such as photoisomerization, photodimerization, photoelimination, and photopolymerization. These reactions bring about the changes in electronic structure of photoreactive compounds, which result in the refractive index changes of polymer films. Photoisomerization of photochromic compounds is one of the attractive candidates for making refractive index patterns in polymer films reversibly. 3-9 However many photochromic compounds become colored after photoisomerization with absorption bands in the visible region, which may disturb the transmittance of probing light in optical † To whom correspondence should be addressed.devices. 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 appli...

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Section: Introductionsupporting

confidence: 91%

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

Murase

Shibata

Furukawa

et al. 2003

Polym J

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“…Photochromic compounds are well known for inducing reversible photoisomerization2,5–11 and have been studied by many groups for application in write‐read‐erase recording devices. On the other hand, photopolymerization, photolocking, and other irreversible photochemical reactions12–21 are applicable to read‐only optical memories, holography, microlenses, and waveguide lithography. For these applications, large refractive index changes induced by photochemical reactions in polymer films should be achieved, and transparency in a wide visible region both before and after photoirradiation is also desired.…”

Section: Introductionmentioning

confidence: 99%

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

Kato

Horie

2002

Macro Chemistry & Physics

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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).

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“…As a result of great demand for advanced optical materials such as plastic optical fiber, the photochemical decrease in refractive index for polymer films has attracted considerable attention for the past decade. − We succeeded in lowering the refractive index of poly(methyl methacrylate) (PMMA) film (doped with hydroxy-substituted diarylnitrones) by as much as 0.014 (−Δ n ) by their quantitative photochemical conversions into diarylformamides showing a much weaker π-conjugation . On the other hand, there are only a few studies directed toward the photochemical increase in refractive index for a given polymer film. − Langer et al . reported that the photoirradiation of polymers bearing thiocyanate pendants enhances the polymer refractive index by 0.031; an additional increase in refractive index is observed upon treating the polymer with hydrazine (Δ n = +0.035).…”

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A Photoinduced Refractive Index Increase in Poly(methyl methacrylate) Film Doped withN-Acetyl-α-dehydroarylalanine Naphthyl Esters

et al. 2005

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As a result of great demand for advanced optical materials such as plastic optical fiber, 1 the photochemical decrease in refractive index for polymer films has attracted considerable attention for the past decade. [2][3][4] We succeeded in lowering the refractive index of poly-(methyl methacrylate) (PMMA) film (doped with hydroxy-substituted diarylnitrones) by as much as 0.014 (-∆n) by their quantitative photochemical conversions into diarylformamides showing a much weaker π-conjugation. 3 On the other hand, there are only a few studies directed toward the photochemical increase in refractive index for a given polymer film. [6][7][8][9][10] reported that the photoirradiation of polymers bearing thiocyanate pendants enhances the polymer refractive index by 0.031; an additional increase in refractive index is observed upon treating the polymer with hydrazine (∆n ) +0.035). Murase et al. 7 also showed that the 3 h photochemical and 3 h thermal treatments of PMMA film doped with 30 wt % of phenyl azide raise the index of this film by 0.0161. While the refractive index changes described above seem to be sufficient magnitude for utilizing these polymers as optical materials, it is necessary to increase the stability of polymer refractive index and also to speed up the photochemical transformation being responsible for the refractive index change of a given polymer film.In the course of our systematic study regarding the excited-state reactivities of N-acyl-R-dehydroarylalanines, it was found that (Z)-N-acetyl-R-dehydrophenylalanine aryl ester derivatives in the singlet excited state undergo the heterolytic cleavage of the ester C(dO)-O bond to eventually form the corresponding oxazolones and aryl alcohols by way of the cyclization of acylinium intermediates (Scheme 1). 11 In contrast to the photoisomerization of diarylnitrone derivatives, the photoheterolysis of dehydrophenylalanine aryl esters gave oxazolones as one of the major products, the absorption of which appeared on the much longer wavelength side than that of the aryl esters. Thus, the novel photochemical transformation of these esters into oxazolones results in an enhancement in the π-conjugation, namely, the linear polarizability of given molecules, which allows us to propose that this photoreaction is accompanied by an increase in refractive index. In this Communication we present the results which demonstrate that the short period of time irradiation of PMMA film doped with N-acetyl-R-dehydrophenylalanine 1-naphthyl ester (1a) or N-acetyl-R-dehydro(1-naphthyl)alanine 1-naphthyl ester (1b) increases the refractive index of this polymer film greatly, and then our refractive index photocontrol system enables application to new optical materials.The starting (Z)-isomers of 1a and 1b were prepared by the ring-opening reactions of (Z)-2-methyl-4-(benzylidene)-5(4H)-oxazolone (2a) and (Z)-2-methyl-4-(1-naphthylmethylene)-5(4H)-oxazolone (2b) with 1-naphthol in dry chloroform containing triethylamine, respectively. 12,13 In Figure 1 are typically shown UV absorp...

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Large Photoinduced Refractive Index Change in a Polyimide Film by Charge-Transfer Complex Formation with a Polymer-Bound Phenylazide Fragment

Cited by 5 publications

References 10 publications

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

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

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

A Photoinduced Refractive Index Increase in Poly(methyl methacrylate) Film Doped withN-Acetyl-α-dehydroarylalanine Naphthyl Esters

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