Microencapsulation of oil by polymer mixture–ionic surfactant interaction induced coacervation

In a ternary mixture composed of 0.7% hydroxypropylmethyl cellulose (HPMC), 0.3% sodium carboxymethyl cellulose (NaCMC), and 0.00–2.00% sodium dodecylsulfate (SDS) various interactions between components take place. The interactions depend on SDS concentration and may result in HPMC–SDS complex formation which is thermodynamically incompatible with NaCMC. Such a ternary mixture phase separates into a coacervate rich in HPMC–SDS complex and equilibrium solution rich in NaCMC. In this paper, it was shown that viscoelastic properties of the coacervate are influenced by HPMC/NaCMC/SDS interaction. Emulsions of sunflower oil in ternary HPMC/NaCMC/SDS mixtures were prepared, and deposition of coacervate (of different viscoelastic properties) at the O/W interface was investigated in order to prepare oil-containing microcapsules with a coacervate shell of different properties. Deposition and stability of the coacervate shell depend on SDS concentration in emulsion. Powder of microcapsules was obtained by spray drying, and barrier properties of microcapsules’ shell were investigated by oil extraction. Amount of extracted oil correlates with viscoelastic properties of corresponding coacervate.