2006 Volume 13 Issue 325 Pages 390-400
Droplets of water-in-oil-in-water (w/o /w) emulsion were prepared by utilizing sodium alginate solution (microorganism protectant and phase-separation material) incorporated microorganism (denitrifying bacteria : Paracoccus denitrificans IF013301) [internal aqueous solution] and dichloromethane (DCM) dissolved polymethylmethacrylate (PMMA, wall material) possessing good chemical and mechanical strength, polyethylene glycol (PEG) and sorbitan monooleate (emulsion stabilizer) [organic solution]. These droplets could be formed core-shell microcapsules with a large single core and a porous wall by the combination of phase separation and solvent evaporation. The internal aqueous solution was necessary to form hollow structure, and the optimum concentration of the sodium alginate solution that functions as microorganism protectant and phase-separation material was 3% (w/w). PEG and sorbitan monooleate were so important factor to prepare excellent microcapsules influenced on hollow structure and surface morphology. Moreover, the thickness of PMMA shell could be controlled by changing the concentration of PMMA for DCM. In the composition condition of PMMA 1.5 g/DCM 20 g, the prepared microcapsules had an average wall thickness of 30 pm and a large hollow core. Although PMMA shell was tended to thicken by adding 1 g of the microorganism, this phenomenon could be improved by decreasing the quantity of the microorganism to 0.2 g. Thus, in this study, the materials that compose the PMMA microcapsules were clarified the influence on the capsule structures.
