Roughness Control of Layer-by-Layer and Alternative Spray Films from Congo Red and PAH via Laser Light Irradiation

Abstract

Films from congo red (CR) alternated with poly(allylamine hydrochloride), PAH, were prepared by layer-by-layer and alternative spray techniques. In order to investigate the change of roughness induced by laser light irradiation (532 nm), both kinds of films were characterized by using UV-visible spectroscopy and atomic force microscopy (AFM). At different irradiation times, layer-by-layer, LbL, films showed small changes in the roughness and irregular behavior, whereas spray films exhibited higher and a regular decreasing of roughness with increasing irradiation time. The higher roughness of spray films as compared with the LbL ones was attributed to different formation mechanisms of the films. The decreasing of the roughness as a function of the irradiation time (exhibited by the spray films) was associated to surface relaxation due to the interplay between photoisomerization of congo red dye and the heating of the sample during the laser light irradiation. The results suggested that the alternative spray technique is the best choose to control of roughness of the films by using light irradiation.

Ascorbic Acid and BSA Protein in Solution and Films: Interaction and Surface Morphological Structure

“…BSA/AA films were adsorbed on quartz slides (36,0 mm × 14,0 mm × 1,0 mm). The fabrication procedures of layer by layer (LbL) followed essentially those described by Cardoso et al [10]. The adsorbed amount, which is proportional to absorbance, was monitored by measuring the UV-vis absorption spectra with a double-beam Thermo Scientific spectrophotometer model Genesys 10.…”