# Enhancement of Mechanical Properties of PCL/PLA/DMSO2 Composites for Bone Tissue Engineering
## 4 Conclusions  
In this study, the tailored composites comprising PLA with 20 wt% PCL and 10, 20, and 30 wt % DMSO\({}_{2}\) were characterized and investigated to enhance mechanical properties, including yield strength, modulus, and hydrophilicity. The following conclusions were derived:  
1. When DMSO\({}_{2}\) was added, the hydrophilicity was improved due to its high surface energy. The highest hydrophilicity was observed in the PLA/PCL/30 wt% DMSO\({}_{2}\) composite. The contact angle of PLA/PCL/30 wt% DMSO\({}_{2}\) composites decreased by 4.57-14.99% compared to other composites. Therefore, in order to enhance the initial cell attachment, the addition of DMSO\({}_{2}\) was necessary.
2. As DSMO\({}_{2}\) content increased, yield strengths and moduli were increased. The highest yield strength was observed in the PLA/PCL/30 wt% DMSO\({}_{2}\) composite specimen. The yield strength was 2.81-239.49% higher than that of other composites. The pure PLA specimen showed brittle behavior, and in the order of PLA/PCL composites, PLA/PCL/10,20, and 30 wt% DMSO\({}_{2}\) composites, and pure PCL, ductile behaviors were observed in stress-strain curves.  
Figure 7: FTIR spectra: (**a**) pure PLA, (**b**) pure PCL, (**c**) PLA/PCL composites, (**d**) PLA/PCL/10 wt% DMSO\({}_{2}\) composites, (**e**) PLA/PCL/20 wt% DMSO\({}_{2}\) composites, and (**f**) PLA/PCL/30 wt% DMSO\({}_{2}\) composites.  
In PLA/PCL/DMSO\({}_{2}\) composites, hydrogen bonding mechanisms were formed. The pure PLA specimen showed brittle characteristics, and the pure PCL specimen displayed ductile characteristics with the elongated matrix. In PLA/PCL composites, a PCL filler debonding challenge occurred on the PLA matrix. The PLA matrix mixed with PCL and DMSO\({}_{2}\) exhibited ductile characteristics with dimple features. Ductility and yield strength increased, attributed to the enhanced intensity hydrogen bands with an increase in DMSO\({}_{2}\) content. Therefore, the interface adhesion between PLA and PCL improved, resulting in improved mechanical properties.  
For the PLA/PCL/DMSO\({}_{2}\) system, as DMSO\({}_{2}\) fillers were added and increased, yield strength and modulus were increased compared to other composites except for the pure PLA. Hydrophilicity and ductility were also improved. This study effectively customized the yield strength, hydrophilicity, and ductility for the PLA/PCL/DMSO\({}_{2}\) system. Therefore, the newly developed PLA/PCL/DMSO\({}_{2}\) composites have the potential to be extended for application as biomaterials in the field of bone tissue engineering.  
Conceptualization, K.-E.M., S.Y. and C.K.; methodology, K.-E.M., J.-W.J., S.Y. and C.K.; investigation, K.-E.M. and J.-W.J.; writing--original draft preparation, K.-E.M.; writing--review and editing, C.K. and S.Y.; project administration, C.K. All authors have read and agreed to the published version of the manuscript.  
This study has been conducted with the support of the Korea Institute of Industrial Technology as \"Development of controllable mechanical and biological properties scaffold based on additive manufacturing (KITECH JE-22-0012)\".  
Not applicable.  
The data presented in this study are available on request from the corresponding author.  
The authors declare no conflicts of interest.