Universität zu Köln

Bushmelev, Alexey (2016). Synthesis of Anisotropic Magnetic Nanoobjects Designed for Locomotion in External Magnetic Fields. PhD thesis, Universität zu Köln.

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Abstract

The subject of the present work is the synthesis of novel nanoscale objects, designed for self-propulsion under external actuation. The synthesized objects present asymmetric hybrid particles, consisting of a magnetic core and polymer flagella and their hydrodynamic properties under the actuation by external magnetic fields are investigated. The single-domain ferromagnetic cobalt ferrite nanoparticles are prepared by thermal decomposition of a mixture of metalorganic complexes based on iron (III) cobalt (II) in non-polar solvents. Further modification of the particles includes the growth of the silver particle on the surface of the cobalt ferrite particle to form a dumbbell-shaped heterodimer. Different possible mechanisms of dumbbell formation are discussed. A polyelectrolyte tail with ability to adjust the persistence length of the polymer, and thus the stiffness of the tail, by variation of pH is attached to the particles. A polymer tail consisting of a polyacrylic acid chain is synthesized by hydrolysis of poly(tert-butyl acrylate) obtained by atom transfer radical polymerization (ATRP). A functional thiol end-group enables selective attachment of the tail to the silver part of the dumbbell, resulting in an asymmetric functionalization of the dumbbells. The calculations on the propulsion force and the sperm number for the resulting particles reveal a theoretical possibility for the propelled motion. Under the actuation of the particles with flagella by alternating magnetic field an increase in the diffusion coefficient compared to non-actuated or non-functionalized particles is observed. Further development of such systems for application as nanomotors or in drug delivery is promising.

Item Type:	Thesis (PhD thesis)
Translated abstract:	Abstract Language In dieser Arbeit wird die Synthese neuartiger Nanoobjekte, die für eine autonome Bewegung unter externer Aktuation konzipiert sind, behandelt. Diese Objekte liegen in Form asymmetrischer Partikel vor, die aus einem magnetischen Kern und Polymergeißeln bestehen. Die hydrodynamischen Eigenschaften dieser Objekte werden unter Aktuirung durch ein externes Magnetfeld untersucht. Die eindomänigen ferromagnetischen Cobaltferritnanopartikel werden durch thermische Zersetzung einer Mischung aus metallorganischen Eisen(III)- und Cobalt(II)-Komplexen in unpolaren Lösungsmitteln erhalten. Um im nächsten Schritt dumbbell-artige Heterodimere zu erhalten, erfolgt das Wachstum von Silberpartikeln auf der Oberfläche der Cobaltferritnanopartikel. Die verschiedenen möglichen Formationsmechanismen der Dumbbellbildung werden diskutiert. Polyelektrolytgeißeln, deren Persistenzlänge und somit die Steifigkeit der Ketten durch den pH-Wert der Lösung German
Creators:	Creators Email ORCID ORCID Put Code Bushmelev, Alexey alexey.bushmelev@uni-koeln.de UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-70387
Date:	25 October 2016
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Chemistry > Institute of Physical Chemistry
Subjects:	Chemistry and allied sciences
Uncontrolled Keywords:	Keywords Language nanoswimmers, magnetic particles, dumbbells, diffusion, magnetic actuation English
Date of oral exam:	29 June 2016
Referee:	Name Academic Title Schmidt, Annette Prof. Dr.
Funders:	NanoSciE+
Projects:	MagNaSwimmers
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/7038