Page 419 - IJB-10-5

International Journal of Bioprinting Stability of 3D-printed PEO tablets

induce a plasticizing effect on the EC polymer. HPC is also can be attributed to its intermolecular interaction with
an amorphous polymer that exhibits a flat line. Its glass polymers used in the formulations.
27
transition temperature should be between 100–120°, but The T of PEO in PM samples was ~72°, which
m
this was hardly detectable in the DSC graph as mentioned decreased to ~66° for HME and ~64° for printed samples.
in other studies. For PEO, the two M (0.9 and 7 M) This pattern was also noticed in another study where T of
28
w
m
displayed relatively similar melting points at 73.74 and PEO decreased for HME. Table 2 displays changes in the
13
73.06°, respectively. In agreement with this, it has been T of PEO in each formulation. The decrease in T could
m
m
reported that high M PEOs typically have relatively similar result from PEO depolymerization (i.e., reduction of M
w
w
T values. The T value of PEO (−50° ) was not the focus following degradation) or a reduction in its crystallinity.
9,11
29
m
g
of this study. The melting point of the original theophylline PEO undergoes crystallinity reduction after a thermal
was found to be approximately 273°. process, further reducing its T by 7°. Additionally, it has
2,30
m
The DSC traces of the various processed formulations been suggested that mixing PEO with amorphous polymers
exhibited the signature PEO and theophylline melting can restrict its recrystallization after cooling, leading to
31
peaks, indicating the presence of their crystalline forms. a drop in T following thermal processing. To examine
m
The T of EC in F and F tablets was hardly detectable, these mechanisms, GPC was employed, which reported a
4
g
3
which could be attributed to the positioning of the EC T g reduction in M of PEO in HME and 3D-printed samples
w
that may contribute to the reduction in T (discussed in
immediately after the PEO melting peak. This could have Section 3.4). m
caused the peaks to merge, making it difficult to observe
a separate T peak. The T of theophylline decreased from 3.3. X-ray powder diffraction
g
m
approximately 273° in its pure form to 243–250° in PM, X-ray powder diffraction (XRPD) was employed at
HME, and 3D-printed samples for all formulations, which 2θ at 5–50° for raw materials and processed samples

Figure 1. Differential scanning calorimetry (DSC) curves of the starting materials used in this study. Abbreviations: PEO: Polyethylene oxide; HPC:
Hydroxypropyl cellulose; EC: Ethyl cellulose.

Volume 10 Issue 5 (2024) 411 doi: 10.36922/ijb.4055