Controlled localization of FePt nanoparticles in block copolymers for modulation of magnetic properties

COLL 245

Debabrata Patra, dpatra@chem.umass.edu, Sudhanshu Srivastava, Tongxiang Lu, Bappaditya Samanta, bsamanta@chem.umass.edu, and Vincent M. Rotello, rotello@chem.umass.edu. Department of Chemistry, University of Massachusetts at Amherst, 710 North Pleasant Street, Amherst, MA 01003
Nanoscopic magnetic materials have attracted interest for their potential applications in memory devices, high density magnetic storage media and magnetic sensors. Significant efforts have been made to use the block copolymers as a template for patterning metallic nanoparticles in the polymer matrix and to integrate the properties of two disparate materials. Block copolymers with specific morphologies (lamella, cylinder, and sphere) can be used to incorporate nanoparticles in the matrix based upon non-covalent interactions. In our approach, we have chosen polystyrene-b-poly (methyl methacrylate) (PS-b-PMMA), a diblock copolymer to integrate magnetic (FePt) nanoparticles into the bulk matrix. FePt oleate functionalized nanoparticles were synthesized and via hydrophobic-hydrophobic interaction the nanoparticles were sequestered in PS domains. The morphology and the nanoparticles ordering in the polymer matrix before and after annealing were initially analyzed by Small Angle Xray Scattering (SAXS), Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM). The modulation of the magnetic behavior i.e. their blocking temperature (TB) of the polymer/nanoparticle at different loadings of the particle before and after annealing were also analyzed and will be discussed.