Hydrolysis of Cellulose Acetate and Cellulose Acetate Butyrate Pseudolatexes Prepared by a Solvent Evaporation-Microfluidization Method

Abstract

Aqueous colloidal Cellulose acetate dispersions have recently been introduced as an alternative to organic polymer solutions for the coating of osmotically active cores with a semipermeable membrane. Cellulose esters are known to hydrolytically degrade in an aqueous environment. This study followed the chemical degradation of pseudolatexes of the cellulose esters, cellulose acetate and cellulose acetate butyrate, over time and as a function of temperature. The pseudolatexes were prepared by a microfluidization-solvent evaporation method. The hydrolysis of the cellulose esters was followed by determining the pH and the amount of the acidic degradation products, acetic and butyric acid, in the aqueous phase of the polymer dispersions with an HPLC assay. The degradation followed a pseudo first-order equation and rate constants and activation energies were calculated. In addition to chemical instability, agglomeration and gelling of the colloidal particles occurred. The pseudolatexes were stable at 4°C, however, if stored at higher temperatures, the preparation of a redispersible polymer powder is recommended.