Preparation of Ethylcellulose Latex by Aqueous Dispersions: Importance of the Particle Size and Plasticizer

Abstract

Based on phase transfer processes ethylcellulose (EC) latex was prepared using dibutyl sebacate (DBS) as plasticizer and oleic acid, ammonia water as an emulsifier to evaluate film-formation properties. Atomic force microscopy was used to characterize the surface features, practical size and differential scanning colorimetry was employed to investigate the effect of plasticizer on glass transition temperature of the resulting materials. The influences of emulsifier concentration on the particle size and on the viscosity were studied. The viscosity initially showed a decreased tendency and then increased linearly with increasing emulsifier concentration. On the other hand, the surface tension decreased considerably up to about 4 wt%, and then it almost remains unchanged with increasing emulsifier concentration. The polymer particle size was identified to be a very crucial formulation parameter, determining the resulting film coating structure and properties. Importantly the particle size decreased systemically with increasing emulsifier concentration up to about 2 wt% and then increased markedly with increasing emulsifier concentration. In addition, the results indicated that the incorporation of polymeric plasticizer substantially reduced the glass transition temperature (Tg) and softening temperature. Moreover, the home-synthesized EC latex could be used effectively to coat materials for drug release.