Synthesis and Characterization of Segmented Liquid Crystalline Polymers with the Azo Group in the Main Chain

Abstract

The synthesis of 4'-hydroxyphenyl(4-hydroxy-3-allyl)azobenzene is reported. The molecule is mesogenic and it can be used for preparing nematic main-chain segmented polymers. The nematic phase is the result of the effect of the side allyl group which, while it destabilizes the crystalline phase, does not affect the occurring of the nematic order. In the crystalline state, a large hexagonal unit cell containing five to six chains is observed for polymers with longer flexible spacer in the chain. Chloroform solutions and thin films of polymers absorb in the UV-visible range, at approximately 332 and 439 nm, corresponding to the p - p* and n - p* electronic transitions of azoaromatic chromophores, respectively. Under appropriate UV irradiation we have obtained the photoisomerizations trans-cis and cis-trans, which are fully reversible in the case of solutions. In the solid state a photostationary state is reached

Synthesis and photoresponsive behavior of the high-Tg azobenzene polymers via RAFT polymerization

“…The diffraction efficiency of SRG is dependent on the surface modulation depth, the grating spacing and the space period [69]. Moreover, gratings can be erased by heating the film to T g [15,[18][19][20][21][22][23]. The high-T g azobenzene polymer PMSt maintained the SRG profile well when the thin film was heated to the temperature lower than T g .…”

“…These SRGs are typically stable substantially below the glass transition temperatures (T g s) of the azobenzene polymers and are erased by heating the polymers to their T g s [16]. Photo fabrication of stable SRGs on the azobenzene polymer films for practical applications therefore requires polymers with good thermal stability and high T g matrices, such as supramolecular polymers [17] and main-chain azobenzene polymers [18][19][20][21][22][23].…”

Structure Modification of an Active Azo-Compound as a Route to New Antimicrobial Compounds

“…The UV-visible spectra for 3a-g are qualitatively only depend on the azobenzene unit, which is the same for all compounds. The UV absorption spectra of A4 analogues in trans configuration, showed the typical absorption bands of the electronic transitions of the azobenzene chromophore [16].…”

A Novel Synthetic Method for Well‐Defined Polymers Containing Benzotriazole and Diazobenzene Chromophores

“…It was high photoresponsitive rate that made it had a potential application in photoelectric materia1. [49,50] Supporting Information available: Plot of ln([M] 0 /[M]) versus polymerization time. IR spectra of PBHEMA, P1, P2 and P3.…”