Structural characterization and properties of an azopolymer arranged in Langmuir and Langmuir–Blodgett films

Abstract

The fabrication of Langmuir and Langmuir–Blodgett (LB) films of an acid-azopolymer (PAzCOOH) is reported. Several techniques were used in their characterization: surface pressure ( π) and surface potential (Δ V) isotherms, UV–vis reflection spectroscopy, and Brewster angle microscopy (BAM) for the Langmuir films and contact angle measurements, UV–vis, fluorescence, IR and Raman spectroscopy and scanning electronic microscopy (SEM) for the LB films. Our study reveals that lateral chains of the polymer situate preferentially onto the water surface with the acid group in contact with the water, where aggregates are scarcely formed. Therefore, the lateral chains of PAzCOOH can be treated as individual monomers to determine structural properties of the fabricated Langmuir and LB films. Monomeric treatment has been used to interpret UV–vis reflection spectroscopy, and a monomer model has been performed to represent lateral chains using density functional theory at B3LYP 6-31G(d,p) level of theory to assign the observed vibrational spectra.