Preparation of stable gelatin/sodium carboxymethylcellulose/sodium lauryl sulfonate microcapsules with ultra-thin capsule wall for electrophoretic displays

Elastic and optical transparent microcapsules with ultra-thin and compact capsule wall for electrophoretic display containing tetrachloroethylene as core material were prepared from gelatin (GE), sodium lauryl sulfonate (SLS) and sodium carboxymethylcellulose (NaCMC) by complex coacervation method. Microcapsules were characterized by scanning electron microscopy, optical microscopy, and thermogravimetric analysis. The pH value influenced formation process was monitored by recording the microstructure of the fragment of the capsules formed at different pH value. Products with branch-like structure formed with the decrease of pH value, by which the capsule wall was knitted up to form compact structure. SLS was found to play an important role in the course of capsule formation, i.e. SLS helped to increase the interaction between gelatin and NaCMC and facilitate the complex coacervation reaction. In the case of 1.0 mM SLS addition, GE/NaCMC/SLS microcapsules with ultra-thin capsule wall, 200 nm in thickness, can be prepared. The capsule owns high thermal stability and good barrier property, both of which prevent core materials from penetrating outside the capsules and are favor of the practical application for the capsules in areas of electrophoretic displays.