Novel STY/nBA/GMA and STY/nBA/MAA core-shell latex blends: Film formation, particle morphology, and cross-linking. 20. A spectroscopic study

These studies focus on behavior of sodium dioctylsulfosuccinate (SDOSS) surfactant molecules in styrene/n-butyl acrylate/glycidyl methacrylate (Sty/nBA/GMA) and styrene/n-butyl acrylate/methacrylic acid (Sty/nBA/MAA) blended latexes during their film formation process. Using a combination of Fourier transform infrared (FT-IR) microanalysis and FT-Raman techniques, not only stratification of SDOSS surfactant molecules during film formation process can be assessed but also the effect of latex particle structures and cross linking reactions during coalescence can be determined. For Sty/nBA/GMA. and Sty/nBA/MAA blended copolymer latexes, SDOSS exhibit nonuniform distributions at the film air (F-A) interface. However, for core/shell Sty/nBA-GMA and Sty/nBA-MAA blended latexes, SDOSS is distributed uniformly near the F-A interface, and its concentration levels are lower as compared to copolymer latex blends. At elevated coalescence temperatures, SDOSS migration to the F-A interface is prohibited due to cross-linking reactions between epoxy and acid groups. Microanalysis results show that SDOSS migration to the F-A interface is initiated after the majority of H2O (>95%) evaporates from the film. Furthermore, these studies show that latex particle surface morphology, particle-particle interdiffusion, and cross-linking reactions play a significant role in controlling mobility of low molecular weight species in latex films.