Surface relief gratings in photoaddressable polymers generated by cw holography

Baldus, O.; Zilker, Stephan J.

doi:10.1007/s003400100531

Cited by 54 publications

(36 citation statements)

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“…Additionally, the generated birefringence of the polarization grating film can be estimated from experimentally observed DE and the Jones's matrix of the phase grating. [4,25,26,30] Table 1 summarizes the induced birefringence between 0.14 and 0.20, and these values are consistent with the values of the birefringent film obtained by irradiating with uniform LPUV light. [28] On the other hand, when irradiated with PC beams, the DE varied as the polarization of monitoring light was rotated (shown in Fig.…”

supporting

confidence: 79%

Formation of Polarization Gratings and Surface Relief Gratings in Photocrosslinkable Polymer Liquid Crystals by Polarization Holography

Kawatsuki¹,

Hasegawa

Ono³

et al. 2003

Advanced Materials

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diazole [12], and 2,7-bis(4¢,4¢,5¢,5¢-tetramethyl-1¢,3¢,2¢-dioxaborolan-2¢-yl)-9-(2¢¢-ethylhexyl)-9-hexylfluorene (1) [13] were prepared following previously published procedures.4,7-Di-2¢-thienyl-2,1,3-benzothiadiazole: To a stirred solution of 4,7-dibromo-2,1,3-benzotiadiazole (1.32 g, 4.5 mmol), and tetrakis(triphenylphosphine)-Pd(0) (95 mg, 0.09 mmol) in 1,2-dimethoxyethane (50 mL) was added 2-thiophene boronic acid (1.5 g, 11.7 mmol) and 1 M NaHCO 3 (40 mL). The mixture was refluxed overnight and 1,2-dimethoxyethane was evaporated under vacuum. The product was extracted with diethyl ether, successively washed with 1 M NaOH and water, and dried over Na 2 SO 4 . Removal of the solvent afforded the crude product as a red oil that was further purified using flash chromatography (silica gel, petroleum ether 40±60 C/ethyl acetate, 50:1 as eluent) to yield 1.15 g (85 %) of the product as red crystals. 4,7-Di-2¢-(5¢-bromo)-thienyl-2,1,3-benzothiadiazole (2): To a stirred solution of 4,7-di-2¢-thienyl-2,1,3-benzothiadiazole (1.44 g, 4.8 mmol) in dimethylformamide (DMF) (25 mL), was added NBS (2.05 g, 11.5 mmol) in darkness. The mixture was stirred at room temperature for 16 h and 2 M HCl was added. The product was extracted into chloroform and the organic phase was washed with 10 % sodium bisulfite, 2 M HCl and water successively and dried over Na 2 SO 4 . The solvent was removed to afford the product as dark red crystals that were recrystallized from chloroform to afford 1.30 g, (59 % Poly(2,7-(9-(2¢-ethylhexyl)-9-hexyl-fluorene)-alt-5,5-(4¢,7¢-di-2-thienyl-2¢,1¢,3¢-benzothiadiazole)) (PFDTBT): 4,7-Di-2¢-(5¢-bromo)-thienyl-2,1,3-benzothiadiazole (0.15 g, 0.33 mmol) was mixed with 2,7-bis(4¢,4¢,5¢,5¢-tetramethyl-1¢,3¢,2¢-dioxaborolan-2¢-yl)-9-(2¢¢-ethylhexyl)-9-hexylfluorene (0.22 g, 0.36 mmol, 1.1 equiv), tetrakis(triphenylphosphine)Pd(0) (3.0 mg, 2.6 lmol) and toluene (6 mL) and refluxed for 10 min under N 2 . Tetraethylammonium hydroxide (1.0 mL, 20 wt.-% in water, 1.4 mmol) was added with a syringe and the mixture was refluxed for 2.5 h. Bromobenzene (0.05 g, 0.32 mmol) was added and after 1 h reflux phenylboronic acid (0.06 g, 0.5 mmol) was added. After 1 h reflux the polymer was precipitated in MeOH and filtered off. The polymer was dissolved in CHCl 3 and conc. NH 4 OH was added. After stirring overnight the phases were separated and the organic phase was washed with water, filtered and evaporated until 5 mL remained. The polymer was precipitated in methanol and filtered off to yield 0.147 g (approx. 60 %) of the pure polymer. Device Preparation: For all devices, the basic geometry is a thin layer of the conducting polymer complex of PEDOT-PSS (EL grade, Bayer AG) as polymer anode. This layer was deposited by spin-coating on a UV±ozone-treated ITOcoated glass substrate, followed by annealing at 120 C for 5 min, to facilitate the hole collection. The composite single-layer diodes were built by spin-coating solutions with PFDTBT and PCBM (weight ratio 1:4) in chloroform (30 mg mL ±1 ). The polymer layer thickne...

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confidence: 79%

Formation of Polarization Gratings and Surface Relief Gratings in Photocrosslinkable Polymer Liquid Crystals by Polarization Holography

Kawatsuki¹,

Hasegawa

Ono³

et al. 2003

Advanced Materials

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“…8 Mechanisms proposed to explain the mass transport include: isomerization pressure, 9 gradient electric forces, 10 asymmetric diffusion, 11 mean-field forces, 12 and permittivity gradients. 13 In addition to these mechanisms, the inherent fluid dynamics have been modeled, 14 -16 yet the exact nature of the driving force remains unresolved.…”

Section: Introductionmentioning

confidence: 99%

Temperature modeling of laser-irradiated azo-polymer thin films

Yager

Barrett

2004

The Journal of Chemical Physics

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Azobenzene polymer thin films exhibit reversible surface mass transport when irradiated with a light intensity and/or polarization gradient, although the exact mechanism remains unknown. In order to address the role of thermal effects in the surface relief grating formation process peculiar to azo polymers, a cellular automaton simulation was developed to model heat flow in thin films undergoing laser irradiation. Typical irradiation intensities of 50 mW/cm2 resulted in film temperature rises on the order of 5 K, confirmed experimentally. The temperature gradient between the light maxima and minima was found, however, to stabilize at only 10(-4) K within 2 micros. These results indicate that thermal effects play a negligible role during inscription, for films of any thickness. Experiments monitoring surface relief grating formation on substrates of different thermal conductivity confirm that inscription is insensitive to film temperature. Further simulations suggest that high-intensity pulsed irradiation leads to destructive temperatures and sample ablation, not to reversible optical mass transport.

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“…Molecular reorientation, a consequence of the angular hole burning due to multiple trans-cis-trans photoisomerization cycles, leads to photoinduced birefringence and dichroism [7,12,13]. The reversible photoisomerization process can also lead to mass transport, resulting in the formation of surface relief gratings [4][5][6][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. The polymer mass redistribution induced by an interference pattern of two laser beams takes place well below the polymer's glass transition temperature T g .…”

Section: Introductionmentioning

confidence: 99%

“…Numerous mechanisms [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] have been proposed to explain the origin of surface relief gratings in polymers functionalized with azobenzenes. They include thermal gradient mechanisms, asymmetric diffusion based on the creation of a concentration gradient [21][22][23], isomerization pressure [24,25], mechanisms based on electromagnetic forces -mean field theory [18,26], permittivity gradient theory [27] and gradient electric force [15,19,28]. Studying a range of polymers with the same chromophore under the same experimental conditions should shed some light on the relationship between polymer matrix and the magnitude of photoinduced optical anisotropy.…”

Section: Introductionmentioning

confidence: 99%

Holographic grating recording in azobenzene functionalized polymers

et al. 2006

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A group of 22 polymers have been synthesized to test their suitability for recording holographic gratings. Polyamides, polyimides, polyesters and their combinations were functionalized with pendant azobenzene groups containing single or double N=N. The polymers were studied using a standard degenerate two-wave mixing technique, which enables measurement of light-induced periodic modification of polymer refractive index and absorption coefficient by analysis of the diffracted light. Two qualitatively different configurations of the holographic polarization recording were used, s − s and s − p. The relationship between structural properties of polymer matrix and azobenzene groups and the holographic grating recording kinetics and light diffraction efficiency was investigated.

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Surface relief gratings in photoaddressable polymers generated by cw holography

Cited by 54 publications

References 0 publications

Formation of Polarization Gratings and Surface Relief Gratings in Photocrosslinkable Polymer Liquid Crystals by Polarization Holography

Formation of Polarization Gratings and Surface Relief Gratings in Photocrosslinkable Polymer Liquid Crystals by Polarization Holography

Temperature modeling of laser-irradiated azo-polymer thin films

Holographic grating recording in azobenzene functionalized polymers

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