Citation: Mackiewicz, E.;
Wejrzanowski, T.; Adamczyk-Cie´slak,
B.; Oliver, G.J. Polymer–Nickel
Composite Filaments for 3D Printing
of Open Porous Materials. Materials
2022, 15, 1360. https://doi.org/
10.3390/ma15041360
Academic Editors: Ludwig Cardon
and Clemens Holzer
Received: 31 December 2021
Accepted: 10 February 2022
Published: 12 February 2022
Publisher’s Note: MDPI stays neutral
with regard to jurisdictional claims in
published maps and institutional affil-
iations.
Copyright: © 2022 by the authors.
Licensee MDPI, Basel, Switzerland.
This article is an open access article
distributed under the terms and
conditions of the Creative Commons
Attribution (CC BY) license (https://
creativecommons.org/licenses/by/
4.0/).
Article
Polymer–Nickel Composite Filaments for 3D Printing of Open
Porous Materials
Ewelina Mackiewicz
1,
* , Tomasz Wejrzanowski
1,
*, Bogusława Adamczyk-Cie´slak
1
and Graeme J. Oliver
2
1
Division of Materials Design, Faculty of Materials Science and Engineering, Warsaw University of Technology,
Woloska 141, 02-507 Warsaw, Poland; boguslawa.cieslak@pw.edu.pl
2
Department of Mechanical Engineering, Cape Peninsula University of Technology, P.O. Box 1906,
Bellville 7535, South Africa; oliverg@cput.ac.za
* Correspondence: ewelina.mackiewicz@pw.edu.pl (E.M.); tomasz.wejrzanowski@pw.edu.pl (T.W.)
Abstract:
Catalysis has been a key way of improving the efficiency-to-cost ratio of chemical and
electrochemical processes. There have been recent developments in catalyst materials that enable the
development of novel and more sophisticated devices that, for example, can be used in applications,
such as membranes, batteries or fuel cells. Since catalytic reactions occur on the surface, most
catalyst materials are based on open porous structures, which facilitates the transport of fluids (gas
or liquid) and chemical (or electrochemical) specific surface activity, thus determining the overall
efficiency of the device. Noble metals are typically used for low temperature catalysis, whereas lower
cost materials, such as nickel, are used for catalysis at elevated temperatures. 3D printing has the
potential to produce a more sophisticated fit for purpose catalyst material. This article presents the
development, fabrication and performance comparison of three thermoplastic composites where
PLA (polylactic acid), PVB (polyvinyl butyral) or ABS (acrylonitrile butadiene styrene) were used as
the matrix, and nickel particles were used as filler with various volume fractions, from 5 to 25 vol%.
The polymer–metal composites were extruded in the form of filaments and then used for 3D FDM
(Fused Deposition Modeling) printing. The 3D printed composites were heat treated to remove the
polymer and sinter the nickel particles. 3D printed composites were also prepared using nickel foam
as a substrate to increase the final porosity and mechanical strength of the material. The result of the
study demonstrates the ability of the optimized filament materials to be used in the fabrication of
high open porosity (over 60%) structures that could be used in high-temperature catalysis and/or
electrocatalysis.
Keywords:
composites; polymers; additive manufacturing; porous materials; Fused Deposition Modeling
1. Introduction
Three-dimensional (3D) printing is also known as rapid prototyping or additive
manufacturing (AM) of material structures directly from digital models developed with
the use of computer aided design (CAD) software. Therefore, this technology is classified
as a ‘bottom-up’ approach and it is based on the incremental addition of material layers
leading to near net-shape realization of 3D designs. Common additive manufacturing
technologies include: Fused Deposition Modeling (FDM), Stereolithography (SLA), Direct
Ink Writing (DIW), Selective Laser Sintering (SLS) and Selective Laser Melting (SLM) [
1
,
2
].
The methods have interesting scientific and engineering potential in that they allow one
to use a variety of methods for fabrication combining polymers, metals or ceramics in the
form of filaments or powders (also combined). 3D printing thus offers new possibilities
particularly in the more accurate tuning of the structure of functional materials, but also
in modifying their chemical composition [
3
,
4
], as compared with traditional methods.
Therefore, it is seemingly the most advantageous technique for the manufacturing of
porous materials, which are used as heterogeneous catalysts or catalyst supports [
5
–
11
]
Materials 2022, 15, 1360. https://doi.org/10.3390/ma15041360 https://www.mdpi.com/journal/materials
