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International Journal of Bioprinting Effect of G/GO on photocurable resin structure

The SEM images (Figure 3) provide crucial insights inadequate dispersion, incomplete curing, or poor G
into the dispersion of GBN and its correlation with the integration into the matrix. This conclusion is supported
fracture behavior of the material. The R+GO sample, by the observation of the fracture surface, where a ductile
following the applied dispersion protocols, exhibits behavior is not found.
an optimal degree of dispersion. The GO is uniformly
distributed and shows strong interaction with the polymer 5. Conclusion
matrix, being well-integrated within it. This homogeneity
results in an irregular fracture surface, indicating The present study aimed to investigate factors influencing
enhanced toughness. In contrast, the dispersion of G is the effectiveness of GBNs in photocurable acrylic resins
for stereolithography. While previous research identified
markedly inferior, characterized by the presence of distinct
clusters (Figure 3b). Consequently, the fracture surface several factors affecting nanocomposite performance,
is smooth, corroborating the poor interaction with the including nanofiller dispersion and chemical interactions,
polymer matrix. this study revealed that GBN may also produce effects on
polymer chain structure.
These findings align well with the observed mechanical
properties. In the post-cured R+G sample, there was an The presence of G and GO nanoparticles in acrylic
increase in Young’s modulus and a decrease in elongation, resins for 3D printing did not significantly affect
attributed to the rigidity effect of the introduced G. polymerization degree but impacted mechanical
However, this effect was less pronounced due to poor properties and glass transition temperature. Differences
nanoparticle dispersion. In contrast, the GO sample in mechanical properties between samples indicate that
exhibited a decrease in Young’s modulus compared to G GBNs may have different effects in the resin. Particularly,
and an increase in elongation. This can be explained by GO produced a slight increase in tensile strength (5%),
reduced crosslinking, which leads to significant disruption but it was found that it led to a less crosslinked matrix,
of the polymer network, resulting in greater deformability potentially due to its larger size. In the case of G, it showed
and a lower modulus. In the R+GO sample, the reinforcing poor mechanical properties possibly due to inadequate
effect of GO was present but was offset and surpassed dispersion or integration, without affecting crosslinking
by the antagonistic effect of reduced crosslinking. The degree. Therefore, the observed differences between the
impact of GO on the crosslinking of the polymer network various nanocomposites are due to changes induced in the
could be mitigated through surface modifications, such as resin structure by the presence of the nanofillers, rather
silanization, as previously demonstrated by Uysal et al. In than the effect of the nanofillers themselves.
49
their study, it was shown that silanization of the surface of
nanomaterials can significantly enhance the physical and Acknowledgments
chemical properties of the polymer network. None.
It is noteworthy that R+GO fracture surface
exhibited significantly higher ductility, showing Funding
uniformly dispersed undulations. This suggests that GO This work was supported by Comillas Pontifical University
nanoparticles may effectively provide obstacles to the (grant number PP2020_08).
crack propagation. 8,50 This observation indicates that
the lack of expected improvements may be the result of Conflict of interest
a change in the polymer structure, particularly from a
crosslinking perspective. The authors declare they have no competing interests.
The polymer crosslinking degree is evident in the Author contributions
calculated M after post-curing. Results indicated that
c
R+GO exhibited a less crosslinked polymer structure. This Conceptualization: S. Lopez de Armentia, E. Paz
could be attributed to the larger size of GO, which impedes Formal analysis: S. Lopez de Armentia, R. Gimenez, J.C.
proper formation of the reticulated network structure, del Real, B. Serrano, J.C. Cabanelas, E. Paz
resulting in a less crosslinked matrix and consequently Investigation: S. Lopez de Armentia, R. Gimenez, B.
weaker mechanical performance. Conversely, while G Serrano, E. Paz
appears to have no significant impact on the crosslinking Methodology: J.C. del Real, J.C. Cabanelas
of the final polymer matrix, possibly due to its smaller Writing–original draft: S. Lopez de Armentia, E. Paz
size and lower chemical reactivity compared to GO, the Writing–review & editing: R. Gimenez, J.C. del Real, B.
observed poor mechanical properties may result from Serrano, J.C. Cabanelas

Volume 10 Issue 6 (2024) 205 doi: 10.36922/ijb.4075