ma9b00088_si_001.pdf (2.47 MB)
Nanostructured Bimetallic Block Copolymers as Precursors to Magnetic FePt Nanoparticles
journal contribution
posted on 2019-04-17, 00:00 authored by Sze-Chun Yiu, Adam Nunns, Cheuk-Lam Ho, Jenner Ho-Loong Ngai, Zhengong Meng, Guijun Li, Jessica Gwyther, George R. Whittell, Ian Manners, Wai-Yeung WongPhase-separated block copolymers
(BCPs) that function as precursors
to arrays of FePt nanoparticles (NPs) are of potential interest for
the creation of media for the next-generation high-density magnetic
data storage devices. A series of bimetallic BCPs has been synthesized
by incorporating a complex containing Fe and Pt centers into the coordinating
block of four different poly(styrene-b-4-vinylpyridine)s
(PS-b-P4VPs, P1–P4). To facilitate
phase separation for the resulting metalated BCPs (PM1–PM4), a loading of the FePt-bimetallic complex corresponding to ca.
20% was used. The bulk and thin-film self-assembly of these BCPs was
studied by transmission electron microscopy (TEM) and atomic force
microscopy, respectively. The spherical and cylindrical morphologies
observed for the metalated BCPs corresponded to those observed for
the metal-free BCPs. The products from the pyrolysis of the BCPs in
bulk were also characterized by TEM, powder X-ray diffraction, and
energy-dispersive X-ray spectroscopy, which indicated that the FePt
NPs formed exist in an fct phase with average particle sizes of ca.
4–8 nm within a carbonaceous matrix. A comparison of the pyrolysis
behavior of the metalated BCP (PM3), the metalated P4VP homopolymer (PM5), and the molecular model
organometallic complex revealed the importance of using a nanostructured
BCP approach for the synthesis of ferromagnetic FePt NPs with a smaller
average NP size and a close to 1:1 Fe/Pt stoichiometric ratio.