Fuzzy assembly and second harmonic generation of clay/polymer/dye monolayer films

Fuzzy assembled multicompound films consisting of natural and synthetic colloidal clay particles, poly(diallyldimethylammonium chloride) (PDDA) and the dyes methylene blue (MB+) and 4-(4-[N-allyl-N-methylamino] phenylazo)benzenesulfonic acid, sodium salt (NAMO(-)) have been prepared. The organization of the clay particles was imaged by means of atomic force microscopy. Fuzzy assembled glass/clay/methylene blue films have been investigated by visible spectroscopy, and the spectra were explained in terms of the substrate-clay interaction and clay particle overlap. Glass/clay/PDDA/NAMO films were investigated by means of absorption spectroscopy, polarized absorption spectroscopy, and second harmonic generation. The nonlinear optical properties of the films were found to be determined by the adsorbed amount of NAMO and its noncentrosymmetric organization. These factors are in turn governed by the substrate type, the PDDA concentration, and the clay type. Optimized second harmonic generation for the glass/laponite/ PDDA/NAMO films was found in which the clay particles are deposited-onto a (3-aminopropyl)-trimethoxysilane modified glass surface and PDDA chains are adsorbed from a 0.1 M solution.