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

Abstract

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Tuning of Fiber Optic Surface Reflectivity through Graphene Oxide-Based Layer-by-Layer Film Coatings

“…The obtained values reveal that adsorption of the first GO layer is much slower than for the tenth GO layer, which is in accordance with the literature, specifically for the case of kinetic curves of polyaniline, a conducting polyelectrolyte whose adsorption characteristic time decreases strongly as the number of bilayers already adsorbed increases [33]. The adsorbed amount is seen to increase with the number of adsorbed bilayers already adsorbed due to an increase in surface roughness of the LbL film, as demonstrated by Ferreira et al [36] and, therefore, also demonstrating that one cannot expect these GO films to be uniform. Table 1.…”

In Situ AFM Imaging of Adsorption Kinetics of DPPG Liposomes: A Quantitative Analysis of Surface Roughness

“…Although it proven that the DPPG adsorption mechanism and consequent formation of a lipid bilayer reached its balance before t=3 min [8], afterwards (t=10 min) the rough exponent increased, due to the accumulation of aggregates of liposomes onto the Au/PAH/DPPG-bilayer surface; being which implies a locally rough surface and a decrease of the fractal dimension. After 3 min of DPPG adsorption the rough exponent, , is close to the unit, which is in good agreement with the linear growth equation of the diffusion Villain model [4,24].…”

Nano-Molar Deltamethrin Sensor Based on Electrical Impedance of PAH/PAZO Layer-by-Layer Sensing Films

“…The sensing layer consisted of LBL films prepared with the polyelectrolytes poly[1-[4-(3-carboxy-4-hydroxyphenylazo)benzenesulfonamide]-1,2-ethanediyl, sodium salt] (PAZO ) and poly(allylamine hydrochloride) (PAH), obtained from Aldrich and with the chemical structures shown in Figure 1b and c. The reason for choosing those polyelectrolytes is that their assembly characteristics are well known, namely the growth characteristics and adsorption kinetics [27–30] and PAZO presents two benzene rings—Figure 1a), which are likely to interact with benzene rings of the DM molecule. Relatively to the films' structure, it should be added that as the PAH/PAZO LBL films are obtained by alternated adsorption of layers, the structure of these films can be defined by a sequence of more or less planar bilayers.…”

“…However, the LBL films structure is also influenced by the surface morphology of each layer. For the first five bilayers, it was seen that the surface roughness increases slightly with the number of bilayers [30], which indicates that all bilayers are essentially similar without increase of larger grains and consequently the bilayers are more or less planar with similar values of thickness [31] and roughness [30]. Since the film structure, namely, the thickness and roughness, is also relevant for the sensor response, and being the film composed by a set of bilayers, the resistance and capacitance values of the sensing film can be controlled by the number of bilayers.…”

“…The reason for using PAZO polyelectrolyte is that its azo group-based chemical structure is akin to that of DM, in the sense that they can adsorb through physical interactions. In addition, PAZO is known to be easily assembled in an LBL film form, namely with PAH polyelectrolyte, with all of adsorption kinetics, layers growth and morphology well characterized [27–30]. Thus, in order to investigate the feasibility of this approach, PAH/PAZO LbL films were prepared onto solid glass supports having interdigitated electrodes and both resistance and capacitance of the equivalent circuit which is created measured when the electrodes were immersed in solutions with DM analyte.…”