Electrically-switchable thermo-mechanical 3D microchannel composites - Fabrication, characterisation and modelling

• Applicants: Professor Dr. Rainer Adelung, since 2/2024; Professor Dr.-Ing. Matthias Ziegenhorn
• Subject Area: Synthesis and Properties of Functional Materials
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 501386727

This proposal aims to develop and investigate multi-scale, functional interpenetration composite structures whose physical properties can be changed in a controlled and reversible manner by applying an electrical stimulus. The concept is based on microstructured polymers that are permeated by a disordered network of interconnected micro-channels.By selectively coating the microchannel walls with a thin layer of conductive nanomaterials, such as graphene, electrically conductive interpenetrating composites are created that are characterized by an extremely low volume fraction of conductive material. Thereby, the mechanical properties of the matrix material remain virtually unchanged. Simultaneously, this functionalization enables rapid heating of the composite by Joule heating.In the scope of this proposal, these material properties are utilized to develop novel interpenetrating composite structures that can be rapidly and reversibly electrically switched in their mechanical properties. Therefore, the microchannel network is filled with a thermo-responsive material, whose mechanical properties change in a certain temperature interval. Based on this novel three-phase interpenetrating composite, a rapid and uniform change in the properties of the bulk material can be achieved. By tailoring the microchannel density in a range of 4 % - 40 % and thus the proportion of thermo-responsive filler material, the switching times of two clearly distinguishable mechanical states can be optimized. The core objective of the project is to understand the basic structure-property principles and mechanisms of this functional interpenetrating composite and thereby answering the key questions: What is the relationship between the proportion of thermo-responsive filler material and the associated property change? How do the mechanisms involved influence the switching times?Within the scope of the project, selected interpenetrating composite systems will be manufactured and characterised with respect to their electrical-thermal-mechanical behaviour. The characterisation is based on modelling approaches that can capture the different states (soft, hard) of the interpenetrating composites, map the switching process and allow conclusions towards the variation of the stimulation processes and/or material combinations.Based on the results of the electro-thermal stimulation, other stimuli-responsive interpenetrating composites can be envisaged. The correlation and combination of different stimuli-property pairs will enable the development of multi-stimuli-responsive composites in the future, which are able to change different properties (e.g. magnetic, optical, mechanical) specifically and separately from each other.

• DFG Programme: Research Grants
• Ehemaliger Antragsteller: Dr.-Ing. Fabian Schütt, until 2/2024