(164t) Understanding Processing Effects during Solution Deposition of Polymer Blends

Solution-based processes are attractive for the manufacturing of polymer films because they are fast, inexpensive, and scalable to large areas. When casting blends of polymers or of polymers and colloids, stratification can occur due to surface energy effects and processing effects. Here, we report studies of stratification in blends of bottlebrush polymers with linear polymers with a focus on processing effects that drive stratification. The Peclet number during casting describes the relative rates of solvent evaporation and solute diffusion, and in our studies of blends of linear and bottlebrush polymers, we systematically varied the Peclet number during casting to understand the effect on stratification. We studied model blends of bottlebrush polystyrene (BBPS) and linear deuterated styrene (dPS), and used time-of-flight secondary ion mass spectroscopy (ToF-SIMS) to quantify the segregation of the bottlebrush polymers in the thin film. Additionally, we studied the effect of solvent annealing on stratification after casting the film. We find that solvent annealing can drive a preference for bottlebrush polymers at film interfaces, and varying the Peclet number has a significant impact on stratification. This study provides insight into factors that affect stratification when casting thin film blends and potentially provides a general route to tailor thin film surface properties using additives.