Page 536 - IJB-9-6

International Journal of Bioprinting High-performance SrCS scaffolds via vat photopolymerization

Figure 2. SEM images, element distribution, and particle size distributions of (a–b) SrCS powders, and (c–d) SrCS-40BTA composite powders.

be difficult to fabricate the green body by VPP due to the energy should allow the curing depth 2–3 times as thick as
ceramic suspensions with ideal viscosity below 3 Pa·s at a the sliced layer, which can ensure excellent layer-to-layer
high shear rate for deposition and stereolithography [44-46] . bonding to prevent cracking during sintering. However,
Therefore, we selected SrCS-BTA ceramic suspensions with the excess exposure energy would cause poor forming
a solid loading of 40 vol.% and a viscosity less than 1 Pa·s at accuracy. Therefore, based on the Beer–Lambert model, the
a shear rate of 100 s for VPP process (shown in Figure 3b). exposure energy of 9, 20, 28, and 32 mJ/cm were selected
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2
We investigated the UV light absorption of SrCS-BTA for curing SrCS, SrCS-20BTA, SrCS-30BTA, and SrCS-
composite powders. As shown in Figure 4a, the SrCS-BTA 40BTA suspensions, and the corresponding curing depth
composites revealed a strong UV light absorption at a is shown in Table 1, respectively. In addition, the exposure
accuracy test also shows that the selected exposure energy
wavelength below 350 nm, while the absorption decreased is appropriate (shown in Figure S2 in Supplementary File).
substantially at a wavelength of 350–400 nm. Therefore, the
405 nm wavelength of the UV source was selected to cure Further, we evaluated the UV-curing kinetics of
the SrCS-BTA ceramic suspensions. Exposure energy is the ceramic suspensions by tracking the absorption intensity
most principal factor for VPP, which directly determines of the C=C bond (shown in Figure 4c). Upon UV
the curing depth and forming precision of samples . As irradiation, the unsaturated C=C bonds of HDDA reacted
[40]
shown in Figure 4b, the curing depth varied linearly with with free radicals from the dissociation of TPO and
LnE , and the slope of the fitting equation (D ) gradually transformed into saturated single bonds . Therefore, the
[47]
i
p
decreased with increasing BTA content. Therefore, as the infrared absorption intensity of unsaturated C=C bonds
BTA content increased, more exposure energy was required gradually weakened with the curing reaction. The infrared
for a certain curing depth. Generally, the desired exposure absorption intensity at around 1636 cm-1 was attributed

Figure 3. Viscosities of (a) SrCS suspensions with different solid loading and (b) 40 vol.% SrCS suspensions with different BTA contents at variable shear
rates of 0–1000 s and a constant shear rate of 100 s .
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Volume 9 Issue 6 (2023) 528 https://doi.org/10.36922/ijb.1233