ROLE OF THERMODYNAMIC AND KINETIC FACTORS IN POLYMER DISSOLUTION IN MIXED-SOLVENTS

A model for polymer dissolution in mixed solvents has been developed w ith the purpose of explaining the hitherto unexplained maximum in the dissolution rate with the solvent composition. The variation of the in terface concentration of both the solvents and the dissolution rate wi th the composition of the non-solvent in the dissolution medium is pre dicted. The model predicts an increase in dissolution rate with an inc rease in low molecular weight non-solvent content of the dissolution m edium. However, further increase in the non-solvent content, decreases the dissolution rate. The relative role of kinetic and thermodynamic quality of the solvent is shown to be the reason for this unusual beha viour. The model also predicts reduction in swelling with an increase in non-solvent content of the dissolution medium. The implications of the work in designing mixed solvent systems for microlithography to me et the goal of maximum dissolution rate with minimum swelling are disc ussed.