Photochemical Behavior and Formation of Surface Relief Grating on Self-Assembled Polyion/Dye Composite Film

Abstract

Holographic surface relief gratings (SRGs) were fabricated on composite films assembled by electrostatic layer-by-layer (ELBL) deposition of a polyelectrolyte, poly(dimethyl diallylammonium chloride) (PDAC), and an azo dye, Congo Red (CR). Surface modulation and first-order diffraction efficiency of the SRG were found to increase with the thickness of the PDAC/CR films. Polarized absorption spectra indicated an oriented growth of CR on the PDAC film. Analysis of the film thickness, FTIR, and FT-Raman results confirmed that the electrostatic attraction between CR and PDAC, as well as the π−π interaction between CR chromophores resulting in the formation of J aggregates, lead to formation of PDAC/CR composite films. Photochemical changes of the PDAC/CR films after irradiation were investigated by UV−vis absorption, FTIR, and FT-Raman spectroscopy. The results indicate that in addition to trans ⇔ cis photoisomerization of CR in the composite film, an irreversible photochemical degradation of CR also simultaneously occurs. Recording SRG on PDAC/CR films by s- and p-polarized beams show different behavior compared to spin-coated films of polymers containing functionalized azo chromophores. Our results indicate that the volume collapse due to the photodegradation of CR in the polymeric matrix, as well as gradient force-induced migration due to trans ⇔ cis isomerization cycling of CR contribute to the formation of SRG on the composite films. This approach provides a methodology to fabricate SRGs for optical information storage applications by using the facile ELBL technique to assemble commercially available azo dyes and polyelectrolytes.

Study of assembly of arachidic acid/LDHs hybrid films containing photoactive dyes

“…The red-shift of λ max due to the CR aggregation has also been widely reported [42][43][44]. For example, Yamaki et al [45] have reported the λ max of the CR red-shift to 504 nm upon forming aggregates in a layer-by-layer nanostructured film under a given condition.…”

Morphology characterization of layer-by-layer films from PAH/MA-co-DR13: the role of film thickness

“…The LBL technique is based on the spontaneous adsorption of charged species from solution onto a solid substrate, with the mechanism responsible for adsorption being in most cases ionic interactions. An overall understanding of the adsorption mechanisms for LBL film fabrication has become a key to the development of films with specific and optimized properties for optoelectronics and photonics [9][10][11][12] and sensing [13][14][15][16]. A detailed investigation of adsorption processes in polymeric LBL films requires the knowledge of several factors, including polymer-polymer, polymer-solvent, and polymer-substrate interactions.…”

Azobenzene Polymers for Photonic Applications

“…The location of these functional units (which may be small molecules, pendants on the polyelectrolyte chains, or particles) within the multilayer stack can be controlled with subnanometer precision. A wide variety of functionalities have been demonstrated, including organic molecules (He et al, 2000a), synthetic polymers , biopolymers (Burke and Barrett, 2003b), natural proteins (Caruso and Mo¨hwald, 1999), colloids (Lvov et al, 1997), inorganic nanoparticles (Kotov et al, 1995), clay platelets (Kleinfeld and Ferguson, 1994) (used as a nacre biomimic [Tang et al, 2003]), dendrimers (Watanabe and Regen, 1994), electrochemically active species (Knoll, 1996), functionalized C 60 (Mattoussi et al, 2000), and even, counterintuitively, uncharged and nonpolar polymer chains (Rouse and Ferguson, 2002). Many research groups have investigated the possibility of incorporating optically responsive azobenzene chromophores into the versatile PEM structures (examples presented in Fig.…”