Three-dimensional compositional gradients in water-borne urethanes and latexes: spectroscopic approaches

Stratification of individual components in thermosetting coatings plays an important role during film formation and affects a number of macroscopic pr operties. This behavior is particularly pronounced for water-borne coatings , and therefore molecular level understanding of interactions in latexes an d responsiveness of individual components during coalescence of water-borne polyurethanes are of particular interest. The presence of macromolecular a rrangements and interactions among various components near the film-air Oi- A) and the film-substrate (F-S) interfaces can be effectively monitored usi ng attenuated total reflectance (ATR) and step-scan photoacoustic (SSPA) Fo urier transform infrared (FT-IR) spectroscopy. Both approaches are capable of obtaining information from various surface depths and complement each ot her if one seeks molecular level information from 0 to 150 mum into the fil m. In this presentation combined ATR and PA information along with IR and/o r Raman surface imaging will be presented to establish three-dimensional re presentation of polyurethane film formation and the effect of copolymer/pol ymer blend latexes on coalescence processes in Sty/n-BA. (C) 2000 Published by Elsevier Science S.A.