Description

MOTIVATION
One of the most employed 3D printing techniques for thermoplastics is Fusion Deposition Modelling (FDM), a process where a filament of plastic material is fed through a heated moving head that melts and extrudes it depositing it, layer by layer.
This technique, involving a melting process, is suitable for thermoplastics but not for thermosetting polymers such as silicone rubbers or polyurethanes as they cannot melt once crosslinked. For this reason, the use of thermosetting polymers in 3D printing technology is generally very limited. An intriguing solution to this problem is offered by vitrimers, crosslinked yet re-processable dynamic polymer networks with properties in between those of thermoplastics and thermosetting [1]. Vitrimer chemistry allows the functionalization of commercially available polymers to obtain dynamic crosslinked networks that can flow when heated [2].
The goal of this project is to develop a vitrimer silicone filament for FDM 3D printing that could enable the printing of soft components.

METHODOLOGY
The work will be structured in two distinct phases.
1)    In the first stage silicone chemistry will be studied and optimized. Vitrimer functional groups, vitrimer crosslinker and other molecules necessary to obtain the final network will be synthesized starting from their precursors and analyzed with NMR. Silicones will be then functionalized and crosslinked using click-chemistry reactions.
2)    In the second stage of the project, the effect of silicones MW, of degree of functionalization and of crosslinks density will be studied and correlated to silicone mechanical properties with the aim of finding the best composition to obtain an FDM filament. Materials will be characterized with rheological, creep and tensile tests and with Dynamic Mechanical Analysis.
Finally, an FDM filament will be produced (and eventually reinforced with different particles ranging from fumed silica to magnetic strontium ferrite) to produce soft 3D printed silicone parts [3].

CONTACT INFO
Stefano Menasce (Complex Materials) – stefano.menasce@mat.ethz.ch
Julia Carpenter (Complex Materials) – julia.carpenter@mat.ethz.ch

REFERENCES
[1] Chem. Sci.,2016, 7,30.
[2] Science 356,62–65 (2017)
[3] Phys. Chem. Chem. Phys., 2012, 14, 3400–3407
[4] Macromolecules 2015, 48, 2098-2106
[5] ACS Macro Lett. 2018, 7, 482-486




About Complex Materials

The Complex Materials group is headed by Prof. André R. Studart and was established in 2009. Our research focuses on the creation of complex composite materials and the understanding of how their structures and properties correlate at different length scales.

Using self- and directed assembly methods, we are particularly interested in creating artificial composites that resemble biological materials and incorporate some of their remarkable structures and functions.

As part of the Department of Materials, we offer lectures on the BSc and MSc level focusing on the ceramics parts of the material science curriculum.