Self-Assembly of Polymer-Modified FePt Magnetic Nanoparticles and Block Copolymers

Frank Hartmann; Martin Bitsch; Bart-Jan Niebuur; Marcus Koch; Tobias Kraus; Christian Dietz; Robert W Stark; Christopher R Everett; Peter Müller-Buschbaum; Oliver Janka; Markus Gallei

doi:10.3390/ma16165503

Self-Assembly of Polymer-Modified FePt Magnetic Nanoparticles and Block Copolymers

Materials (Basel). 2023 Aug 8;16(16):5503. doi: 10.3390/ma16165503.

Authors

Frank Hartmann¹, Martin Bitsch¹, Bart-Jan Niebuur², Marcus Koch², Tobias Kraus^{2

3}, Christian Dietz⁴, Robert W Stark⁴, Christopher R Everett⁵, Peter Müller-Buschbaum^{5

6}, Oliver Janka⁷, Markus Gallei^{1

8}

Affiliations

¹ Polymer Chemistry, Faculty of Natural Sciences and Technology, Saarland University, Campus C4 2, 66123 Saarbrücken, Germany.
² INM-Leibniz-Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany.
³ Colloid and Interface Chemistry, Faculty of Natural Sciences and Technology, Saarland University, Campus D2 2, 66123 Saarbrücken, Germany.
⁴ Physics of Surfaces, Institute of Materials Science, Technical University of Darmstadt, Peter-Grünberg-Straße 2, 64287 Darmstadt, Germany.
⁵ Chair for Functional Materials, Department of Physics, TUM School of Natural Sciences, Technical University of Munich, James-Franck-Straße 1, 85748 Garching, Germany.
⁶ Heinz Maier-Leibnitz Zentrum (MLZ), Technical University of Munich, Lichtenbergstraße 1, 85748 Garching, Germany.
⁷ Inorganic Solid-State Chemistry, Faculty of Natural Sciences and Technology, Saarland University, Campus C4 1, 66123 Saarbrücken, Germany.
⁸ Saarene, Saarland Center for Energy Materials and Sustainability, Campus C4 2, 66123 Saarbrücken, Germany.

Abstract

The fabrication of nanocomposites containing magnetic nanoparticles is gaining interest as a model for application in small electronic devices. The self-assembly of block copolymers (BCPs) makes these materials ideal for use as a soft matrix to support the structural ordering of the nanoparticles. In this work, a high-molecular-weight polystyrene-b-poly(methyl methacrylate) block copolymer (PS-b-PMMA) was synthesized through anionic polymerization. The influence of the addition of different ratios of PMMA-coated FePt nanoparticles (NPs) on the self-assembled morphology was investigated using transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS). The self-assembly of the NPs inside the PMMA phase at low particle concentrations was analyzed statistically, and the negative effect of higher particle ratios on the lamellar BCP morphology became visible. The placement of the NPs inside the PMMA phase was also compared to theoretical descriptions. The magnetic addressability of the FePt nanoparticles inside the nanocomposite films was finally analyzed using bimodal magnetic force microscopy and proved the magnetic nature of the nanoparticles inside the microphase-separated BCP films.

Keywords: anionic polymerization; block copolymers; nanocomposites; nanoparticles; self-assembly.

Grants and funding

Instrumentation and technical assistance for this work were provided by the Service Center of X-ray Diffraction, with financial support from Saarland University and German Science Foundation (project number INST 256/349-1). C.R.E and P.M.-B. acknowledge funding from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) via the International Research Training Group 2022 Alberta/Technical University of Munich International Graduate School for Environmentally Responsible Functional Hybrid Materials (ATUMS).