ISBN 978-3-8439-4835-7

978-3-8439-4835-7, Reihe Physikalische Chemie

Julian Seifert
Particle-Matrix Interactions in Hybrid Magnetic Polymer Composites with Varying Network Architecture

218 Seiten, Dissertation Universität Köln (2021), Softcover, A5

Zusammenfassung / Abstract

The incorporation of magnetic nanoparticles into polymer-based elastic matrices leads to soft composites with intrinsic magnetic properties. By magnetic or mechanic stimulation, it is possible to induce anisotropic material properties in these hybrid composites, and thus obtain materials with direction-dependent macroscopic properties, which have enormous application potential.

In this work, the particle-matrix interactions in magnetic polymer composites are systematically analyzed. Starting with soft polymer-based ferrogels with comparably low strength of the mutual interaction, a model system of poly(acrylamide)-based hydrogels is employed, which shows a systematically varying mean mesh size in the size regime of superparamagnetic iron oxide nanoparticles.

Stronger interactions between the embedded particles and the elastic matrix are found in particle-filled elastomers. Here, a novel material architecture is presented, which is formed by poly(dimethylsiloxane)-based elastomer networks that are exclusively crosslinked by highly functional inorganic nanoparticles. The novel particle-crosslinked elastomers here show strongly particle-content depending properties as well as enormous strains at break of up to 1700 %.

For the hybrid particle-filled elastomers, spindle-type hematite particles are employed as particulate crosslinkers. The orientational anisotropy of the embedded particles is investigated by angle-dependent magnetization measurements in addition to small angle X-ray scattering experiments depending on the strain. A tunable anisotropy is found, which depends on the sample architecture, the magnetic field, the particle volume fraction, and the applied strain.

The results presented in this thesis contribute to a better understanding of the particle-matrix interactions in particle-filled polymeric materials and provide substantial insight into the generation and modification of anisotropy in particle-filled polymer networks.