The Early Stages of Coalescence and Polymer Diffusion in Latex Films

WALTER F. SCHROEDER; YUANQIN LIU; JEFFREY C. HALEY; WILLIE LAU; MITCHELL A. WINNIK

Philadelphia, USA

Otro; 236th ACS National Meeting & Exposition; 2008

American Chemical Society

In this work early stages of coalescence and polymer diffusion in latex films based on poly(butyl acrylate-co-methyl methacrylate) were examined by fluorescence resonance energy transfer (FRET). By arresting the latex drying process, our apparatus allowed us performing FRET measurements at various positions across the sample with sub-milimeter resolution, and so determining the extent of polymer interdiffusion as a function of the distance to the drying front. The experiments were performed under fixed humidity conditions. We find that adjacent to the drying front, an increase of relative humidity delays the onset of polymer interdiffusion. This fact shows that coalescence and diffusion do not necessary occur with the passing of the drying front. We can explain our results considering that after the drying front has passed, there still remains a very thin film of water between the packed latex particles that blocks and delays the beginning of polymer interdiffusion.