Long-Term Stability at High Temperatures for Birefringence in PAZO/PAH Layer-by-Layer Films

Abstract

Optical memories with long-term stability at high temperatures have long been pursued in azopolymers with photoinduced birefringence. In this study, we show that the residual birefringence in layer-by-layer (LbL) films made with poly[1-[4-(3-carboxy-4 hydroxyphenylazo)benzene sulfonamido]-1,2-ethanediyl, sodium salt] (PAZO) alternated with poly(allylamine hydrochloride) (PAH) can be tuned by varying the extent of electrostatic interactions with film fabrication at different pHs for PAH. The dynamics of both writing and relaxation processes could be explained with a two-stage mechanism involving the orientation of the chromophores per se and the chain movement. Upon calculating the activation energies for these processes, we demonstrate semiquantitatively that reduced electrostatic interactions in films prepared at higher pH, for which PAH is less charged, are responsible for the longer stability at high temperatures. This is attributed to orientation of PAZO chromophores via cooperative aggregation, where the presence of counterions hindered relaxation.

Azopolymer triggered electrophoretic deposition of MnO2-carbon nanotube composites and polypyrrole coated carbon nanotubes for supercapacitors

“…The surface roughness can result from gas evolution during deposition, related to the electrochemical decomposition of water. 29,35 The spectrum of the deposited PAZO is similar to that of the protonated form of PAZO, prepared in acidic conditions. 5E and F).…”

“…23 The analysis of deposition yield data at different deposition durations at PAZO concentrations of 1 g L À1 indicated that relatively high deposition yield can be achieved (Fig. 35 The adsorptions at 1396 and 1481 cm À1 were related to aromatic C-C/C]C vibrations. The deposition yield data presented in Fig.…”

“…The SEM studies of the lms prepared from aqueous solutions showed signicant surface roughness (Fig. 29,35 The peaks (Fig. The surface roughness can result from gas evolution during deposition, related to the electrochemical decomposition of water.…”

Villain's fractal growth of poly[1-[4-(3-carboxy-4-hydroxyphenylazo) benzenesulfonamido]-1,2-ethanediyl, sodium salt] J-aggregates onto layer-by-layer films and its effect on film absorbance spectrum

“…Recently, it has been shown that the residual birefringence attained in LbL films of poly(allylamine hydrochloride) (PAH) alternated with poly[1-[4-(3-carboxy-4 hydroxyphenylazo)benzene sulfonamido]-1,2-ethanediyl, sodium salt] (PAZO) can be tuned by controlling the extent of electrostatic interactions during film fabrication. 19 In addition, it has been demonstrated that the reduction of electrostatic interactions leads to orientation of PAZO chromophores via cooperative aggregation, where the presence of polyelectrolyte counterions hinder relaxation. This result is relevant for the production of optical storage devices with long-term stability at high temperatures and, also, indicates that the growth of these films should be better characterized from of point view of adsorbed molecules and surface morphology.…”

Fabrication and Characterization of Light-responsive Multilayer Films of Chitosan and Azopolymer

“…Layer-by-layer (LbL) adsorption of oppositely charged polyelectrolytes onto solid substrates has shown to be a versatile technique for the development of polyelectrolyte multilayer (PEM) films, where not only thickness and composition can be controlled precisely, but also their properties may be tuned synergistically with a combination of distinct materials in the same film [1][2][3][4][5][6].…”