E/Z reversible photoisomerization of methyl orange doped polyacrylic acid‐based polyelectrolyte brush films

Abstract

The photoswitching behavior of the polyacrylic acid (PAA) doped by methyl orange (MO) brush film was investigated using spectral analysis of UV‐Vis absorbance, Fourier Transformation Infrared spectroscopy, 2D electrical conductivity mapping and Atomic Force Microscopy. The kinetics and time evolution of the photoisomerization of the PAA‐MO PEBs film from E‐state to Z‐state by UV‐light irradiation, and reverse thermal relaxation to E‐state was explored. The results confirm that the photoisomerization kinetics of the overall peak is the superposition of the photoisomerization kinetics of normalS2πnormalπ* transition, low‐ and high‐frequency of the normalS1nnormalπ* transition bands. The E–Z transformation led to transforming the azobenzene from flat with no dipole moment to 3.0 D dipole moment. Hence, the electrical conductivity escalated accordingly. The transformation of E‐state to Z‐state led to the collapse of the formed brushes because of the angular rotational momentum consequent to E–Z isomerization.

Visible light assisted photooxidative facile degradation of azo dyes in water using a green method

“… 54 The absorption peak at 1340 cm −1 was observed before degradation and after degradation peak was observed at 1321 cm −1 so the wavenumber decreased indicating that the blue shift occurred due to a stretching vibrational band of C–N functionality. 55 After degradation there were various peaks observed in degraded samples at 3524, 3311, 3211, 2899, 2368, 1751, 1716, 1654, 1321cm −1 shown in Fig. 6 .…”