Photoinduced birefringence in azopolymer doped with Au nanoparticles

Abstract

A study of the photoinduced birefringence in nanocomposite thin films of the azopolymer PAZO (poly[1-[4-(3-carboxy-4-hydroxyphenylazo)benzenesulfonamido]-1,2-ethanediyl, sodium salt]) doped with gold (Au) nanoparticles (NPs) is presented. The NPs are with a spherical shape and mean size 10 nm. Transmission electron microscopy (TEM) and Dynamic Light Scattering (DLS) analyses of the particles have also been made. Samples were prepared with five different concentrations of the NPs in the azopolymer films varying from 0 (non-doped azopolymer film) to 4 a.u. (1 a.u. = 0.015 wt %). Birefringence was induced by a He-Cd laser with a wavelength 442 nm and measured with probe Diode Pumped Solid State (DPSS) laser at 635 nm. An increase of the photoinduced birefringence in doped azopolymer nanocomposite films compared to samples of undoped azopolymers was observed. The maximal enhancement was achieved for films with 2 a.u. of Au NPs.

Increase of SRG modulation depth in azopolymers-nanoparticles hybrid materials

“…Eventually, for much larger concentrations of NPs the opposite effect occurs: NPs occupy larger space reducing the number of azo groups per unit of volume. This possible influence of the NPs in the available free volume is in accordance with the observations of Nazarova [18,21,15] about the changes in the induced birefringence of samples doped with NPs. In addition, the first order diffraction efficiency and its dependence on the SRG modulation is analyzed.…”

“…Regarding azopolymer-metallic NPs hybrids, some results previously published showed increased values of the photo-orientation rate (𝜏) and the maximum birefringence (∆𝑛 ), for certain concentrations of Ag and Au NPs [15][16][17]. In general, the results were explained phenomenologically by the effect of LSPPR and the scattering in the NPs.…”

Polarization properties of two-dimensional polarization holographic gratings inscribed in azopolymer thin films

“…The two recording beams recombine on the sample's surface at angle 2θ = 20° corresponding to grating period Λ ≈ 1.3 μm. To monitor the process and measure the DE without influencing the recording we need probe laser with wavelength outside of the absorption band of PAZO [18] so we used diode-pumped solid state laser at 635 nm (B&W Tek Inc.). Via quarter-wave plate we control the polarization of the probe laser and for the kinetics of the process it is set up as circular so the diffraction efficiency is measured in real time DE(t).…”

Nanocomposite Photoanisotropic Materials for Applications in Polarization Holography and Photonics

“…Nanoparticles with different compositions have attracted the attention of researchers as possible dopant components, such as quantum dots (QDs) [134][135][136], carbon nanotubes (CNTs), and carbon nanofibers (CNFs) [137,138], ZnO [128,[139][140][141][142], SiO 2 [143,144], TiO 2 [145][146][147][148], semiconductor nanoparticles like tellurium containing chalcogenide system (GeTe 4 ) 100−x Cu x [149] and goethite (α-FeOOH) nanorods [129,150], nanozeolites [151], and upconverting nanoparticles (UCNPs) [152]. Gold (Au) and silver (Ag) NPs are the most commonly used metallic nanoparticles [132,146,[153][154][155][156][157][158][159][160][161]. Studies have also been conducted with bioactive metals, such as copper and nickel (Cu, Ni) [162,163].…”

“…The chemical structures of some azo-containing polymers used for nanocomposite components are presented in Figure 2. A very commonly used azopolymer, as we have [164]); (e) SEM image of carbon nanotubes (reprinted with permission from [137]); (f) SEM image of carbon nanofibers (reprinted with permission from [137]); (g) TEM image of upconverting hexagonal nanoparticles (scale bar is 200 nm) (reprinted with permission from [152]); (h) TEM image of Au colloidal solution (reprinted with permission from [160]); (i) TEM image of Au NPs (reprinted with permission from [156]); (j) TEM image of Ag (reprinted with permission from [155]); (k) SEM image of Ag nanocubes. The inset shows a TEM image of silver nanocubes (scale bar is 100 nm) (reprinted with permission from [165]); (l) TEM image of goethite nanorods (reprinted with permission from [150]).…”