10.1021/acs.biomac.9b01112.s001
Shubham Jain
Shubham
Jain
Tiziana Fuoco
Tiziana
Fuoco
Mohammed A. Yassin
Mohammed A.
Yassin
Kamal Mustafa
Kamal
Mustafa
Anna Finne-Wistrand
Anna
Finne-Wistrand
Printability and Critical Insight into Polymer Properties
during Direct-Extrusion Based 3D Printing of Medical Grade Polylactide
and Copolyesters
American Chemical Society
2019
PLLA
GA
printing parameters
PDLGA
3 D Printing
PCLA
degradation profile
co
use degradable polymers
3 D printing techniques
CL
PLGA
Medical Grade Polylactide
LA
2019-10-11 12:33:20
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Printability_and_Critical_Insight_into_Polymer_Properties_during_Direct-Extrusion_Based_3D_Printing_of_Medical_Grade_Polylactide_and_Copolyesters/9970910
Various 3D printing
techniques currently use degradable polymers
such as aliphatic polyesters to create well-defined scaffolds. Even
though degradable polymers are influenced by the printing process,
and this subsequently affects the mechanical properties and degradation
profile, degradation of the polymer during the process is not often
considered. Degradable scaffolds are today printed and cell–material
interactions evaluated without considering the fact that the polymer
change while printing the scaffold. Our methodology herein was to
vary the printing parameters such as temperature, pressure, and speed
to define the relationship between printability, polymer microstructure,
composition, degradation profile during the process, and rheological
behavior. We used high molecular weight medical-grade (co)polymers,
poly(l-lactide-<i>co</i>-ε-caprolactone)
(PCLA), poly(l-lactide-<i>co</i>-glycolide) (PLGA),
and poly(d,l-lactide-<i>co</i>-glycolide)
(PDLGA), with l-lactide content ranging from 25 to 100 mol
%, for printing in an extrusion-based printer (3D Bioplotter). Optical
microscopy confirmed that the polymers were printable at high resolution
and good speed, until a certain degree of degradation. The results
show also that printability can not be claimed just by optimizing
printing parameters and highlight the importance of a careful analysis
of how the polymer’s structure and properties vary during printing.
The polymers thermally decomposed from the first processing minute
and caused a decrease in the average block length of the lactide blocks
in the copolymers and generated lower crystallinity. Poly(l-lactide) (PLLA) and PCLA are printable at a higher molecular weight,
less degradation before printing was possible, compared to PLGA and
PDLGA, a result explained by the higher complex viscosity and more
elastic polymeric melt of the copolymer containing glycolide (GA)
and lactide (LA). In more detail, copolymers comprised of LA and ε-caprolactone
(CL) formed lower molecular weight compounds over the course of printing,
while the PLGA copolymer was more susceptible to intermolecular transesterification
reactions, which do not affect the overall molecular weight, but cause
changes in the copolymer microstructure. This results in a longer
printing time for PLGA than PLLA and PCLA.