Abstract
α-Amino acid based polyester amides (PEAs) are promising candidates for additive manufacturing (AM), as they unite the flexibility and degradability of polyesters and good thermomechanical properties of polyamides in one structure. Introducing α-amino acids in the PEA structure brings additional advantages such as (i) good cytocompatibility and biodegradability, (ii) providing strong amide bonds, enhancing the hydrogen-bonding network, (iii) the introduction of pendant reactive functional groups, and (iv) providing good cell–polymer interactions. However, the application of α-amino acid based PEAs for AM via fused deposition modeling (FDM), an important manufacturing technique with unique processing characteristics and requirements, is still lacking. With the aim to exploit the combination of these advantages in the creation, design, and function of additively manufactured scaffolds using FDM, we report the structure–function relationship of a series of α-amino acid based PEAs. The PEAs with three different molecular weights were synthesized via the active solution polycondensation, and their performance for AM applications was studied in comparison with a commercial biomedical grade copolymer of l-lactide and glycolide (PLGA). The PEAs, in addition to good thermal stability, showed semicrystalline behavior with proper mechanical properties, which were different depending on their molecular weight and crystallinity. They showed more ductility due to their lower glass transition temperature (Tg; 18–20 °C) compared with PLGA (57 °C). The rheology studies revealed that the end-capping of PEAs is of high importance for preventing cross-linking and further polymerization during the melt extrusion and for the steadiness and reproducibility of FDM. Furthermore, our data regarding the steady 3D printing performance, good polymer–cell interactions, and low cytotoxicity suggest that α-amino acid based PEAs can be introduced as favorable polymers for future AM applications in tissue engineering. In addition, their ability for formation of bonelike apatite in the simulated body fluid (SBF) indicates their potential for bone tissue engineering applications.
Highlights
During the past few decades, additive manufacturing (AM) has attracted considerable attention from researchers around the world
In order to study the effect of the molecular weight of the polyester amides (PEAs) on fused deposition modeling (FDM) 3D printing, three different molecular weights were synthesized
The PEAs were synthesized via the active solution polycondensation of the monomers A and B in a mole ratio of 1:1 under dry conditions
Summary
During the past few decades, additive manufacturing (AM) has attracted considerable attention from researchers around the world. The difference in the molecular weight of the PEAs clearly affected their complex viscosity values, which is an important factor for their AM procedure as it influences extrudability, interfacial bonding, solidification and shape retention.[50] considering (i) the cooling rate in the rheometer to be distinctly lower than during melt deposition in FDM and (ii) heat transfer of successively added filaments, and so cold crystallization upon reheating is minimized,[51] PLGA likely remained amorphous in the final scaffold. As the complex viscosity of the non-end-capped polymers increased, as a result of melt-condensation and crosslinking, their G′′ values increased, which indicates an increase in the viscous behavior as time proceeds This increment for the end-capped samples is much less because of less condensation reactions in the end-capped PEAs during the stability test (Figure 5C vs D). This could be due to the higher surface area of the 3D printed samples compared to the films, which could further promote the formation of HA.[46]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
