Nanostructured diblock copolymer films with embedded magnetic nanoparticles

作者：Xia Xin; Metwalli Ezzeldin; Ruderer Matthias A; Koerstgens Volker; Busch Peter; Boeni Peter; Mueller Buschbaum Peter

来源：Journal of Physics: Condensed Matter , 2011, 23(25): 254203.

DOI：10.1088/0953-8984/23/25/254203

Nanostructured diblock copolymer films with embedded magnetic nanoparticles are prepared by solution casting. The diblock copolymer polystyrene-block-polymethylmethacrylate with a fully deuterated polystyrene block of a weight ratio of 0.22 is used as a structure-directing matrix. Maghemite nanoparticles (gamma-Fe2O3) are coated with polystyrene and thus have a selective affinity to the minority block of the diblock copolymer. The hybrid film morphology is investigated as a function of nanoparticle concentration. The surface structure is probed with atomic force microscopy and scanning electron microscopy. The inner film structure and the structure at the polymer-substrate interface are detected with grazing incidence small angle neutron scattering (GISANS). Irrespective of the nanoparticle concentration a well developed micro-phase separation structure is present. From the Bragg peaks observed in the GISANS data a linear nanoparticle concentration dependence of the inter-domain spacing of the micro-phase separation structure is determined. The superparamagnetic and blocking behavior can be explained with a generalized Stoner-Wohlfarth-Neel theory which includes either an elastic torque being exerted on the nanoparticles by the field or a broad distribution of anisotropy constants.

• 出版日期2011-6-29