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Materials Science in Additive Manufacturing High-performance materials in AM

A B C

F
D E

Figure 8. Schematic illustration of the process to fabricate the material extrusion (MEX)-printed polyetheretherketone (PEEK) skull implant. (A) Flow
chart of the MEX printing of PEEK skull implant. (B) Printing data processing and acquiring control parameters. (C) MEX printing of the PEEK skull
implant. (D) The MEX-printed PEEK prosthesis of the skull. (E and F) Comparison between the MEX-printed PEEK skull implant and the patient-specific
[75]
designed PEEK skull prostheses. The front (E) and back (F) views of the printing accuracy are shown .
the treatment of inflammation in patients as well as the methods, limiting the value of this material in cutting-
regenerative bone repair of implants at a later stage. edge applications. AM technology allows the polyimide
Similar modifications can also yield sulfonated PEEK material to be processed with precision, enabling it to be
[79]
(SPEEK), which can be adhered to other antimicrobial used in more complex scenarios .
substances to achieve an improved inflammatory The precursors of polyimide materials can be used
environment in implanted soft tissues. The antimicrobial for manufacturing by means of VPP technology due to
peptide HHC36 has been shown to provide up to 10 days of their ability to conveniently bind photocurable functional
extended sterilization effect on SPEEK by a simple solvent groups . In 2017, researchers prepared photosensitive
[80]
evaporation method (HSPEEK) , which opens further polyimide oligomers into solvent-free photocurable
[77]
possibilities for minimally invasive bone and joint grafting inks and processed them using VPP technology,
and repair in the elderly. The flowchart of the synthesizing successfully obtaining products with excellent mechanical
HSPEEK is shown in Figure 9. properties . In the same period, the printing of insoluble
[81]
However, the integration of this novel material obtained engineering thermoplastic polyimides was also successfully
by modification with AM technology has yet to be further accomplished with the VPP technology using soluble
explored, but its promising future in the biomedical field precursor polymers for chemical cross-linking under light
[82]
will undoubtedly point to the need for complex structures, induction and post-printing heat treatment .
making this area highly explorable. These early studies have demonstrated that the

3.2. Polyimide polyimide materials are compatible with AM technology. It
also paves the way for the subsequent use of AM technology
Polyimide, a material that predates PEEK, is one of the to improve the functionality as well as the practical value
most heat-resistant polymers currently available . It has of polyimide and polyimide-based composites. For
[78]
a rigid aromatic molecular structure and therefore exhibits example, new research has begun to focus on greening the
excellent corrosion and heat resistance, mechanical AM process and has incorporated this concept into the
and electrical properties and can be used at extreme research process, resulting in an alternative to the harmful
[79]
operating temperatures. It is currently of great value in organic solvents required for the AM process for polyimide
many fields such as space exploration, defense and security, materials . On the other hand, in response to the low
[83]
electronics, and electrical appliances. strength, poor thermal stability and high curing shrinkage
On the other hand, given its stability at high temperatures, of photocurable resin materials currently available on
it is difficult to fuse polyimide in conventional processing the market, new light-curable polyimide inks for the

Volume 2 Issue 3 (2023) 8 https://doi.org/10.36922/msam.1587