## 4 Conclusions and Outlook  
In summary, chitosan/CaCO\({}_{3}\) composite hydrogel materials were successfully prepared in this study, providing a novel approach for the development of ceramic/polymer composites by utilizing chitosan hydrogel as a substrate for the in situ growth of CaCO \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Mineralization Time**} & **Young’s Moduli** & **Tensile Strength** & **Ultimate Strain** \\  & E [MPa] & \(\sigma_{\text{m}}\) [MPa] & \(\varepsilon_{\text{b}}\) [\%] \\ \hline
0 min & 5.59 \(\pm\) 0.34 & 4.64 \(\pm\) 0.50 & 73.64 \(\pm\) 6.68 \\
5 min & 13.84 \(\pm\) 2.15 & 6.68 \(\pm\) 1.71 & 54.87 \(\pm\) 9.67 \\
30 min & 10.91 \(\pm\) 0.86 & 5.74 \(\pm\) 1.03 & 57.68 \(\pm\) 7.21 \\
1 h & 11.68 \(\pm\) 1.38 & 8.72 \(\pm\) 2.90 & 68.05 \(\pm\) 19.15 \\
3 h & 13.88 \(\pm\) 3.11 & 5.37 \(\pm\) 1.13 & 46.34 \(\pm\) 3.41 \\
6 h & 12.15 \(\pm\) 1.57 & 6.00 \(\pm\) 0.63 & 52.12 \(\pm\) 8.04 \\
12 h & 6.96 \(\pm\) 0.21 & 2.42 \(\pm\) 0.54 & 44.47 \(\pm\) 8.06 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Calculated results and error analysis of tensile tests for chitosan/CaCO\({}_{3}\) composite hydrogels at different mineralization times. Figure 8: Stress–strain curve of chitosan/CaCO\({}_{3}\) composite hydrogel at different mineralization times. Compared to the unmineralized chitosan films, mineralized films show an increase in both stiffness and tensile strength. nanoparticles via diffusion. The hydrogel network served as a medium for crystal mineralization, enabling the maintenance of solute diffusion while regulating and controlling crystal morphology. Calcite nanoparticles were formed uniformly inside the chitosan molecular networks with a strong interface between calcite crystals and chitosan chains. The nanostructure resembled that observed previously in natural tissues such as mantis shrimp dactyl club, chiton teeth, and nacre. By adjusting the mineralization time, it was found that the tensile strength of the hydrogel could be significantly enhanced in an optimal range of the mineralization period while maintaining the hydrogel's inherent toughness. Additionally, the in situ growth of CaCO\({}_{3}\) in the chitosan hydrogel using our method ensures good interfacial bonding between the CaCO\({}_{3}\) and chitosan matrix, closely mimicking the biomineralization process in nature. This approach avoids the inhomogeneous agglomeration that may occur when the two components are mixed directly. The next step will be optimizing the mineralization process based on crystallization principles, further adjusting the experimental conditions to more precisely regulate crystal growth in the polymer network. This will deepen our understanding of the diffusion process and crystal growth mechanism in the gel, ultimately leading to the development of composites with improved performance. Moreover, beyond CaCO\({}_{3}\) and chitosan, other materials can be explored to expand the performance and application areas of ceramic/polymer composites, paving the way for future advancements in tissue engineering, materials science, and biomedicine. The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app14209193/s1](https://www.mdpi.com/article/10.3390/app14209193/s1)]([https://www.mdpi.com/article/10.3390/app14209193/s1](https://www.mdpi.com/article/10.3390/app14209193/s1)), Figure S1: Images of the surface morphology of chitosan/CaCO\({}_{3}\) composite hydrogel at different mineralization time; Figure S2: TGA of chitosan/CaCO\({}_{3}\) composite hydrogel at different times; Figure S3: Images of the surface morphology of chitosan/CaCO\({}_{3}\) composite hydrogel; Figure S4: SEM image of CaCO\({}_{3}\) on the surface of chitosan/CaCO\({}_{3}\) composite hydrogel; Figure S5: The printing route and sample photographs of chitosan/CaCO\({}_{3}\) composite hydrogel. Conceptualization, W.H. and B.W. ; methodology, W.H. and X.Z. ; validation, X.Z., Z.Z. and W.C.; formal analysis, X.Z. ; investigation, X.Z. ; resources, W.H. and B.W.