SURFACE AND INTERFACIAL FTIR SPECTROSCOPIC STUDIES OF LATEXES .1. SURFACTANT COPOLYMER INTERACTIONS

Molecular level interactions between surfactants and copolymers as well as transient effects during latex film formation play an important role in latex technology. Photoacoustic (PA) and attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectroscopy were utilized for the characterization of interactions between sodium dioctylsulfosuccinate and ethyl acrylate/methacrylic acid (SDOSS/EA/MAA) copolymer in latex films at both the film-air and film-substrate interfaces. It is shown that the splitting of the asymmetric S-O stretching normal vibrations of the SO3- groups in the presence of Na+ counterions occurs only when weak-COOH acid groups of latex are present. The absence of the COOH groups either by neutralization of latex or intentional synthesis eliminates the S-O...H-O- associations that are the primary source of the symmetry changes resulting in the splitting of the S-O symmetric mode at 1050 cm-1 to two bands at 1046 and 1056 cm-1.