FT-IR imaging of polymer dissolution by solvent mixtures. 1. Solvents

The dissolution of poly(alpha -methylstyrene) (PAMS) by a binary solvent mi xture containing systematically varied amounts of methyl isobutyl ketone (M IBK) in deuterated cyclohexane was studied using FT-IR imaging. From each s equential image in a timed sequence, spatially resolved spectral data were gathered and absorbance profiles for the field of view were obtained. This allowed the study of solvent penetration and quantitative analysis of the d issolution process from concentration profiles. The dissolution of the poly mer was found to vary linearly with time for similar to 150 mum dissolved l ayer. The dissolution rate was found to increase linearly with MIBK concent ration. In each solvent mixture, diffusion profiles were characteristic of case LI diffusion. No solvent component segregation was seen. It is demonst rated that PT-IR imaging is a viable tool to characterize the dissolution o f polymers by multicomponent solvents.