Improved stability of emulsions in preparation of uniform small-sized konjac glucomanna (KGM) microspheres with epoxy-based polymer membrane by premix membrane emulsification

Abstract

Uniform small-sized (<10 μm) Konjac glucomanna (KGM) microspheres have great application prospects in bio-separation, drug delivery and controlled release. Premix membrane emulsification is an effective method to prepare uniform small-sized KGM microspheres. However, since KGM solution bears strong alkalinity, it requires the membrane to have a hydrophobic surface resistant to alkali. In this study, uniform small-sized KGM microspheres were prepared with epoxy-based polymer membrane (EP) we developed by premix membrane emulsification. It was found that emulsion coalescence and flocculation occurred frequently due to the high interface energy and sedimentation velocity of KGM emulsions. Emulsion stability had a significant influence on the uniformity and dispersity of the final KGM microspheres. To improve the stability of the emulsions, the effects of the concentration of the emulsifier, the viscosity of the KGM solution, the oil phase composition and the feeding method of epoxy chloropropane (EC) on the preparation results were studied. Under optimal preparation conditions (emulsifier 5 wt % PO-5s, KGM III (145.6 mPa·s), weight ratio of liquid paraffin (LP) to petroleum ether (PE) 11:1), uniform and stable KGM emulsions (d = 7.47 μm, CV = 15.35%) were obtained and crosslinked without emulsion-instable phenomena.