Photoresponsive Behavior of Heterocyclic Azo Polymers with Various Functional Groups

Abstract

Here, we report on efficiency of light-induced processes in a series of methacrylic polymers containing heterocyclic azo moieties covalently attached to the polymer backbone. The optical response of the polymers was investigated in experiments on photoinduced birefringence measurements and surface relief gratings inscription upon irradiation with polarized blue light. The experimental results indicate that the presence of acceptor-type (Br) substituent in the side benzene ring linked to the heterocyclic ring has a beneficial effect on efficiency of birefringence generation, while incorporation of donor-type (CH3, OCH3) substituents lowers the level of photoinduced birefringence. Moreover, the process of surface relief structure formation was successfully observed for all studied polymers. The obtained surface-modulation depth reached up to 100 nm for two out of four investigated materials. No straightforward relation between the induced azo chromophore alignment level and the efficiency of mass-transport process is observed.

Effect of 2-Methylthiazole Group on Photoinduced Birefringence of Thiazole-Azo Dye Host–Guest Systems at Different Wavelengths of Irradiation

“…Photoinduced birefringence measurements were performed for 405 nm, 445 nm and 532 nm excitation wavelengths. The experimental configuration used in the studies with violet and blue irradiation was presented elsewhere [ 35 ]. The intensity of each beam (from diode lasers) was 100 mW/cm 2 .…”

“…The excitation and probe beams were linearly polarized in the directions forming an angle of 45°. The measurement technique is based on detecting the intensity of the probe beam after passing through the thin film situated between two crossed polarizers [ 35 ]. The details of the experimental configuration were described elsewhere [ 36 , 37 , 38 ], whereas Figure 8 shows the experimental configuration of photoinduced birefringence at excitation of a CW laser (λ exc.…”

Synthesis, spectroscopic characterization and biological activities of some metal complexes with new heterocyclic azodye ligand 2-(2-hydroxynaphthalen-1-yl azo)-pyridin-3-ol

“…The role in execution of dye as synthetic colourants in textile, 1,2 printing 3,4 and in paper manufacturing is very significant. 5,6 Azo dyes are widely used in liquid crystal display colour filters, 7 lasers, nonlinear optics, photovoltaic production, 8 chemical sensors, as drug, cosmetics, food and in many organic synthesis 9 . Azo groups attached to benzene rings, naphthalenes, aromatic heterocycles or to enolizable groups give colour of different intensities.…”

Photoinduced Split of the Cavity Mode in Photonic Crystals Based on Porous Silicon Filled with Photochromic Azobenzene-Containing Substances

“…Another efficient way of phototuning the structure and optical properties of photochromic glass-forming substances is the so-called Weigert effect representing photo-orientation of the azobenzene chromophores under polarized-light action. − Photoinduced repetitive cycles of E–Z–E isomerization accompanied by rotational diffusion of chromophores align the chromophores in the direction orthogonal to the polarization of incident excitation light (Figure ). In amorphous polymers or glass-forming low-molar-mass substances this effect enables to obtain high values of dichroism or birefringence. − In polydomain LC samples, uniaxial alignment of mesogenic groups could be achieved (although an ordered LC state in some cases prevents the photo-orientation process, especially for the smectic phase).…”