The cellulose solvent system N,N-dimethylacetamide/lithium chloride revisited: the effect of water on physicochemical properties and chemical stability

Abstract

The water content in the binary system N,N-dimethylacetamide/lithium chloride (DMAc/LiCl), a common cellulose solvent, was proven to be a crucial parameter. A quick detn. of water content in DMAc based on the solvatochromism of a UV-active betain probe dye was developed and validated. An analogous method, based on the solvatochromic fluorescence shift of Zelinskij's dye, which strongly depends on the solvent polarity, was established for water detn. in DMAc contg. LiCl. Precise physicochem. data of the system DMAc/LiCl, e.g. d., viscosity, and cond., were obtained. The limiting soly. for LiCl in abs. DMAc is 8.46 wt.%. As shown by light scattering expts., water in DMAc/LiCl induces aggregation upon standing for longer periods of time, which is even more prominent for dild. solns. and those having a poor state of dissoln.