Particle size-dependent magnetic properties of poly (methyl methacrylate) core/nickel shell hybrid spheres

The particle size-dependent magnetic properties of the core/shell type of the poly (methyl methacrylate) (PMMA)/Ni hybrid microspheres were investigated. The electroless nickel plating was carried out by controlling optimum conditions in terms of the initial pH, plating temperature, amount of the nickel plating solution on the Ni content and coating thickness. The thickness of the Ni shell varied from 70 to 225 nm from the PSS (Particle Size Systems) measurement and from 73 to 285 nm from the theoretical calculation depending on the core sizes. Although the Ni thickness varied upon the core size, the coated total Ni content was approximately 32 % and this was independent of the core sizes due to the same concentration of nickel plating solution. In addition, the magnetic moment and the coercivity of PMMA/Ni hybrid particles were 0.14 emu · g−1 and 0.12 kOe, respectively, which are independent of the particle sizes. Thus, the magnetic moment and coercivity of PMMA core/nickel shell hybrid particles are not influenced by the particle size or the nickel shell thickness, but affected by the total contents of nickel.