Confined Crystallization of Spin-Crossover Nanoparticles in Block-Copolymer Micelles

Christoph Göbel; Christian Hils; Markus Drechsler; Dirk Baabe; Andreas Greiner; Holger Schmalz; Birgit Weber

doi:10.1002/anie.201914343

Confined Crystallization of Spin-Crossover Nanoparticles in Block-Copolymer Micelles

Angew Chem Int Ed Engl. 2020 Mar 27;59(14):5765-5770. doi: 10.1002/anie.201914343. Epub 2020 Feb 3.

Authors

Christoph Göbel¹, Christian Hils², Markus Drechsler³, Dirk Baabe⁴, Andreas Greiner⁵, Holger Schmalz⁵, Birgit Weber¹

Affiliations

¹ Department of Chemistry, Inorganic Chemistry IV, Unversität Bayreuth, Universitätsstrasse 30, 95440, Bayreuth, Germany.
² Department of Chemistry, Macromolecular Chemistry II, Universität Bayreuth, Universitätsstr. 30, 95440, Bayreuth, Germany.
³ Keylab Electron and Optical Microscopy, Bavarian Polymer Institute, Universität Bayreuth, Universitätsstrasse 30, 95440, Bayreuth, Germany.
⁴ Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, 38106, Braunschweig, Germany.
⁵ Department of Chemistry, Macromolecular Chemistry II and Keylab Synthesis and Molecular Characterization, Bavarian Polymer Institute, Universität Bayreuth, Universitätsstrasse 30, 95440, Bayreuth, Germany.

Abstract

Nanoparticles of the spin-crossover coordination polymer [FeL(bipy)]_n were synthesized by confined crystallization within the core of polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) diblock copolymer micelles. The 4VP units in the micellar core act as coordination sites for the Fe complex. In the bulk material, the spin-crossover nanoparticles in the core are well isolated from each other allowing thermal treatment without disintegration of their structure. During annealing above the glass transition temperature of the PS block, the transition temperature is shifted gradually to higher temperatures from the as-synthesized product (T_1/2 ↓=163 K and T_1/2 ↑=170 K) to the annealed product (T_1/2 ↓=203 K and T_1/2 ↑=217 K) along with an increase in hysteresis width from 6 K to 14 K. Thus, the spin-crossover properties can be shifted towards the properties of the related bulk material. The stability of the nanocomposite allows further processing, such as electrospinning from solution.

Keywords: block copolymers; composite materials; electrospinning; nanoparticles; spin crossover.

Abstract

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