Title

Superparamagnetic Nanocomposites Based On Poly(styrene-b-ethylene/butylene-b-styrene)/Cobalt Ferrite Compositions

Document Type

Article

Publication Date

4-1-2006

Department

Polymers and High Performance Materials

Abstract

Magnetic nanoparticles were created in or around the sulfonated (s) polystyrene domains in a phase separated poly[styrene-b-(ethylene-co-butylene)-b-styrene)] block copolymer (BCP) using an in situ inorganic precipitation procedure. The sBCP was neutralized with a mixed iron/cobalt chloride electrolyte and the doped samples were converted to their oxides by reaction with sodium hydroxide and further washing with water. Transmission electron microscopy indicated the presence of nanoparticles in the 5-25 nm size range. The metal oxide particle structures were studied using select area electron diffraction, which revealed that they are of the cobalt iron oxide composition (CoFe2O4). These nanocomposites were shown, using a superconducting quantum interference device magnetometer, to be superparamagnetic at 300 K and ferrimagnetic at 5 K. Nanocomposites consisting of smaller particles have a blocking temperature of 70 K, whereas it was 140 K for larger particles. (C) 2005 Elsevier B.V. All rights reserved.

Publication Title

Journal of Magnetism and Magnetic Materials

Volume

299

Issue

1

First Page

211

Last Page

218