The increase in diffraction efficiency of an azobenzene side-chain polymer using imidazolium and ammonium ionic liquids

The advancement of the information age has intensified the focus on photosensitive materials for information storage devices. To develop new photosensitive two azobenzene side-chain polymers i.e., poly(E)-3-(4-((4-nitrophenyl)diazenyl)phenoxy)propyl acrylate (polymer-1) and poly(E)-3-(4-((2-methoxy-4-nitrophenyl)diazenyl)phenoxy)propyl acrylate (polymer-2), were developed, and their diffraction efficiency was evaluated. The impact of ionic liquids (ILs) on the diffraction efficiency was evaluated by combining the polymers with imidazolium and ammonium families of ILs such as 1-butyl-3-methylimidazolium bromide [Bmim]Br, 1-ethyl-3-methyl-imidazolium-bromide [Emim]Br (imidazolium ILs), and triethylammonium methanesulfonate [TMEAS] (ammonium IL). The molecular interaction of both azobenzene side-chain polymers with the ILs was evaluated before the diffraction efficiency studies by employing UV–vis, FT-IR, and confocal Raman spectroscopies. The spectroscopic studies revealed the interaction of the polymers with the imidazolium and ammonium ILs. The mean diffraction efficiency of polymers-1 and −2 were ∼0.05 and ∼0.022%, respectively. After the addition of the ILs, the diffraction efficiency increased. The highest diffraction efficiency was achieved with the polymer-2 + [Emim]Br system of 3.5% and polymer-2 + TEMS combination of 4.03%. Therefore, although the diffraction efficiency of polymer-1 was higher than that of polymer-2, after adding the ILs, the diffraction efficiency of polymer-2 surpassed that of the polymer-1 + ILs system.