The Respective Roles of Metal Salts in The Dissolution Process of Poly(1-oxotrimethylene) in Their Aqueous Solutions

The respective roles of the aqueous solutions of zinc chloride (ZnCl2), calcium chloride (CaCl2), and lithium chloride (LiCl) in the dissolution process of poly(1-oxotrimethylene) (ECO) were investigated. The ECO was soluble only in the ZnCl2-based aqueous solutions. The ZnCl2 aqueous solutions dissolved ECO when the metal salt content exceeded 65 wt%, following a mechanism analogous to Lewis acid/base reaction. In the case of the aqueous solution of 70 wt% ZnCl2, the ECO solubility was limited to 6 wt% because of heterogeneity of the resultant solution. However, an addition of CaCl2 (10 wt%) or LiCl (10 wt%) to the ZnCl2 aqueous solution widened the soluble range of ECO up to 8 wt%. The Cole-Cole plot exhibited that CaCl2 improved homogeneity of the solution but LiCl reduced it. In addition, the addition of both LiCl and CaCl2 decreased the dynamic viscosity of the ECO solutions, which was more noticeable with LiCl.