Abstract
In this work series of “T-type” polyimides with azobenzene or azopyridine moieties were investigated. It is the first report where the “T-type” polyimides with derivatives of azopyridine were investigated. The cis-trans isomerization in the dark in the solid-state was showed. Polyimides with azobenzene derivatives exhibited higher stability of cis-trans recovery than their azobenzene analogues. For the inscription of the surface relief gratings, two different intensities of light (10 and 45 mJ/cm2) and a number of pulses (10 and 100) were used. Polyimides showed the modulation of SRGs up to almost 330 nm. Our studies showed, that azopolyimides are able to orient the nematic liquid crystal molecules in cell-based on effect at the twisted nematic. The obtained maximum value of tON was 0.9 ms (1 kHz, 1.5 V/μm) for polyimide with azobenzene moieties. Azopolyimides may be successfully used in many photonic devices based on the alignment of the liquid crystal mixture i.e. LC diffraction gratings, Fresnel lens, Vortex, in a photo-pattering technology for creating radical and azimuthal orienting layers.
Highlights
One of the fastest-growing fields of science and technology is photonics
We showed that the cis-trans isomerization of azopyridine compounds in the dark is significantly faster than azobenzene derivatives [35,36], side-chain polyimides with derivatives of azopyridine may form higher modulation of surface relief gratings (SRG) than their azobenzene analogues [34]
The azopolyimides were obtained in one-step polycondensation reaction carried out at high temperature
Summary
One of the fastest-growing fields of science and technology is photonics. It includes replacing the electron with photon and practical application of its properties in controlling various optical processes [1,2]. No less important are the physicochemical properties, that the polymeric material characterizes Polyimides, due to their unique properties, i.e. high glass transition temperature and high thermal stability ensuring the stability of photoinduced anisotropy, as well as the ease of manufacture and wide modifiability of the structure, allow to obtain a product with optimal properties for a given optical process, are popular among scientists [9,19,20,21]. As a result of the interaction of photochromic groups of the polymer with a linearly polarized light, it occurs repeated trans-cis-trans isomerization This causes changes in the angular distribution of the chromophores over time. The potential application of azopolyimides as layers for the alignment of the liquid crystals was presented
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