title: Microencapsulation of fragrant oil via in situ polymerization: effects of pH and melamine-formaldehyde molar ratio.
abstract: Microcapsules containing fragrant oil (Foral oil) were synthesized via the in situ polymerization method using melamine-formaldehyde (M-F) as a wall material. The encapsulation efficiency and other physical properties were analysed with varying formaldehyde/melamine (F/M) mole ratio and pH of emulsion medium. The pH of the reaction medium was varied from 5.0-6.0 and the F/M molar ratio, 2.3 - 5.5. Microcapsules containing fragrant oil were synthesized successfully and their particle sizes ranged from 12-15 micro m. Encapsulation efficiency of fragrant oil varied from 67-81%. It was found that both pH and F/M molar ratio have an effect on the separation of M-F prepolymer, consequently the morphology of the surface of the microcapsule was changed as well as encapsulation efficiency. The encapsulation mechanism, focusing on the liquid-liquid phase separation of methylolmelamines and formation of M-F precursor particle, was described to explain the surface morphology and encapsulation efficiency.
authors.affiliation: Nanosphere Process & Technology Laboratory, Department of Chemical Engineering, Yonsei University, 134 Shinchon-Dong, Sudaemoon-Ku, Seoul 120-749, Korea.
authors.forename: H Y
authors.initials: HY
authors.lastname: Lee
authors.forename: S J
authors.initials: SJ
authors.lastname: Lee
authors.forename: I W
authors.initials: IW
authors.lastname: Cheong
authors.forename: J H
authors.initials: JH
authors.lastname: Kim
mesh_terms: D002214:Capsules / Q000737:chemistry; D004339:Drug Compounding / Q000379:methods*; D004655:Emulsions; D005557:Formaldehyde / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008855:Microscopy, Electron, Scanning; D009821:Oils / Q000008:administration & dosage*; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry; D014227:Triazines / Q000737:chemistry
chemical_list: D002214:Capsules; D004655:Emulsions; D009821:Oils; D011108:Polymers; D014227:Triazines; D005557:Formaldehyde; C011907:melamine