ORIENTAL JOURNAL OF CHEMISTRY www.orientjchem.org An International Open Access, Peer Reviewed Research Journal ISSN: 0970-020 X CODEN: OJCHEG 2019, Vol. 35, No.(2): Pg. 516-522 This is an Open Access article licensed under a Creative Commons license: Attribution 4.0 International (CC- BY). Published by Oriental Scientific Publishing Company © 2018 High Encapsulation Efficiency of Magnetite Nanoparticles in Hydrophobic Polymer Microcapsules Using Microsuspension Conventional Radical Polymerization JITTAYA SADCHAIYAPHUM 1 , PONGSATHON PHAPUGRANGKUL 2 , PREEYPORN CHAIYASAT 1,3 and AMORN CHAIYASATA 1,3 * 1 Department of Chemistry, Faculty of Science and Technology, Rajamangala University of Technology Thanyaburi, Klong 6, Thanyaburi, Pathum Thani 12110, Thailand. 2 Biodiversity Research Center, Thailand Institute of Scientific and Technological Research, Pathum Thani 12120, Thailand. 3 Advanced Materials Design and Development (AMDD) Research Unit, Faculty of Science and Technology, Rajamangala University of Technology Thanyaburi, Klong 6, Thanyaburi, Pathum Thani 12110, Thailand. *Corresponding author E-mail: a_chaiyasat@mail.rmutt.ac.th http://dx.doi.org/10.13005/ojc/350202 (Received: February 05, 2019; Accepted: April 02, 2019) ABSTRACT High encapsulation efficiency of magnetite nanoparticles (MNPs; Fe 3 O 4 ) in microcapsules using PDVB as a hydrophobic polymer shell was successfully achieved by microsuspension conventional radical polymerization (ms CRP). MNPs were initially synthesized by co-precipitation of Fe 2+ /Fe 3+ in a binary phase. During the nucleation of MNPs in alkaline aqueous solution existing oleic acid (OA), MNPs were coated with OA (MNPs-OA) before moving to the toluene phase with the addition of salt. At OA concentration of 0.3 wt%, most of the nucleated MNPs were hydrophobic and well dispersed in the toluene phase. Using DVB as a monomer for ms CRP, high encapsulation efficiency (92 %EE) of MNPs-OA was obtained, with low free polymer particle formation. By contrast, large amounts of free polymer particles were observed at low %EE (32%) of MNPs. The main driving force for high %EE was obtained by coating the surface of the MNPs by OA which increased hydrophobicity. Keywords: Microsuspension conventional radical polymerization, Magnetite nanoparticles, Encapsulation efficiency, Microcapsule. INTRODUCTION Magnetic particles have been applied to various fields including magnetic resonance imaging (MRI) 1,2 , drug delivery 3,4 , biosensor 5,6 and separation 7,8 . Iron oxides as magnetite nanoparticles