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Mieloch, et al.

Figure 2. DSC measurement. Cooling step of raw materials (after thermal history erasure).

CNT/polymer nanocomposites and their interfacial
characteristics, see the following article . In our study,
[26]
the addition of CNT resulted in a smoothened surface of
the 3D-printed grids in comparison to pure PCL. As the
data suggest, this effect cannot be explained by changes
in viscosity or crystallinity of the samples. It could,
however, be a result of an increased rate of crystallization,
calculated as Tc onset - Tc. Presumably, CNT facilitate
heat transfer through the polymer providing uniform
temperature distribution, preventing local tensions arising
from a nonequal rate of crystallization due to regional
temperature differences. Contrary to this hypothesis, low
concentrations of a thermoconductive filler are believed
to facilitate phonons scattering at the filler/polymer
interfaces, resulting in the “interface thermal resistance”
phenomenon [27,28] . At this point, the mechanism of surface
smoothening remains unsettled. However, taking into
Figure 3. Mean elastic modulus and mean hardness of raw
materials measured through nanoindentation. Statistical analysis consideration the increase of the modulus cross-over
was performed using one-way ANOVA and post hoc Dunnett’s T3 temperature, Tc and Tc onset, with concomitant lack of
multiple comparisons test. The mean of each column was compared increased overall crystallinity for CNT-reinforced PCL,
to the mean of PCL column. CI = 95%, P value: 0.12 (ns), 0.033(*), supports the notion of enhanced thermal transfer.
0.002 (**), <0.001 (***). Rheology analysis provided insight into the
properties of the CNT/polymer interface. The initial
concentration range of both CNT types provided no increase of zero-rate viscosity at low to medium
statistically significant differences in viability. Pure concentrations of CNT suggests that the strength of
PCL grids did have a minor effect on cell viability. The polymer/polymer interface interactions is lower than the
statistical significance of differences between samples polymer/CNT. However, at high CNT concentrations,
against pure PCL was presented in the Supplementary zero-rate viscosity decreased below pure PCL, signifying
File (Table S1). the CNT/CNT interface being weaker in comparison to
the polymer/polymer interface. Furthermore, the lack
4. Discussion of increased viscosity at lower shear rates indicates that
the CNT-filled PCL does not behave like a yield stress
The data presented highlights several physicochemical, fluid (represented by the Herschel-Bulkley model) .
[29]
mechanical, and biological characteristics of PCL Therefore, it can be concluded that the CNT do not form
reinforced with CNT for 3D printing and tissue cross-linked networks with the polymer chains. Moreover,
engineering. It is important to underline that the it suggests that CNT do not act as nucleation centers
polymer mixing methodology most likely resulted in for PCL crystallization, as was demonstrated for other
nonhomogeneous CNT dispersions within the polymer polymers [30-32] . This finding is corroborated by the DSC
matrix, contributing to various characteristics of the data, revealing that the degree of crystallinity was not
resulting biomaterial. For an extensive overview of significantly affected by the CNT addition. Interestingly,

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