TY - JOUR
T1 - Soap-free synthesis of highly monodisperse magnetic polymer particles with amphoteric initiator
AU - Yamauchi, Noriko
AU - Nagao, Daisuke
AU - Konno, Mikio
N1 - Funding Information:
The authors are grateful to T. Miyazaki for FE-TEM observation. This research was partially supported by research fellowships of the Japan Society for the Promotion of Science for Young Scientists (21-3621) and the Ministry of Education, Culture, Sports, Science, and Technology (20360354, 20681011, and 21656202).
PY - 2010/1
Y1 - 2010/1
N2 - A method applying soap-free emulsion polymerization with an amphoteric initiator, 2,2′-azobis[N-(2-carboxyethyl)-2-2-methyl-propionamidine], is proposed for synthesis of highly monodisperse particles composed of magnetic nanoparticles (Fe3O4/γ-Fe2O3) and polystyrene. The magnetic nanoparticles were pretreated by surface modification for introducing double bonds onto the particles. In the polymerization, magnetic nanoparticles were continuously supplied to the system for a certain period after the initiation of polymerization at various pH. Dissociation degrees of ionizable groups in the initiator molecules were controlled through pH by changing NH3 concentrations at a constant NH4Cl concentration. Selection of suitable pH in the polymerization could produce polymer particles that perfectly incorporated the supplied magnetic nanoparticles. The magnetic polymer particles had a coefficient of variation of size distribution as low as 4.3% with an average diameter of 515 nm and a saturation magnetization of 7.3 emu/g-sample. Electrophoresis measurements indicated that the magnetic polymer particles had an isoelectric point of pH 4.1.
AB - A method applying soap-free emulsion polymerization with an amphoteric initiator, 2,2′-azobis[N-(2-carboxyethyl)-2-2-methyl-propionamidine], is proposed for synthesis of highly monodisperse particles composed of magnetic nanoparticles (Fe3O4/γ-Fe2O3) and polystyrene. The magnetic nanoparticles were pretreated by surface modification for introducing double bonds onto the particles. In the polymerization, magnetic nanoparticles were continuously supplied to the system for a certain period after the initiation of polymerization at various pH. Dissociation degrees of ionizable groups in the initiator molecules were controlled through pH by changing NH3 concentrations at a constant NH4Cl concentration. Selection of suitable pH in the polymerization could produce polymer particles that perfectly incorporated the supplied magnetic nanoparticles. The magnetic polymer particles had a coefficient of variation of size distribution as low as 4.3% with an average diameter of 515 nm and a saturation magnetization of 7.3 emu/g-sample. Electrophoresis measurements indicated that the magnetic polymer particles had an isoelectric point of pH 4.1.
KW - Amphoteric
KW - Magnetic polymer particle
KW - Monodisperse
KW - Soap-free emulsion polymerization
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U2 - 10.1007/s00396-009-2130-0
DO - 10.1007/s00396-009-2130-0
M3 - Article
AN - SCOPUS:76849095843
VL - 288
SP - 55
EP - 61
JO - Colloid and Polymer Science
JF - Colloid and Polymer Science
SN - 0303-402X
IS - 1
ER -