Polymer/polymer interaction in blends of ethyl cellulose with both cellulose derivatives and polyethylene glycol 6000

Abstract

Polymer/polymer interactions in blends of ethyl cellulose with hydroxypropyl methylcellulose, hydroxypropyl cellulose, hydroxypropyl methylcellulose phthalate, cellulose acetate phthalate and polyethylene glycol 6000 have been studied using the torsional braid pendulum. All the film formers were shown to be incompatible with ethyl cellulose exhibiting phase separation throughout the composition range. However, some interaction via the unsubstituted hydroxyl groups did occur, with hydroxypropyl methylcellulose with its increased substitution showing slightly reduced interaction. Both grades of hydroxypropyl methylcellulose phthalate and cellulose acetate phthalate exhibited appreciable interaction and mutual dispersion due to the presence of phthalyl groups. The results are extremely important in understanding the transport mechanisms of such blends when used in pharmaceutical formulations for controlled release.