## 4 Conclusions  
The study demonstrated the influence of various fillers in thermal properties of silicon polymer base composite through a simple and easily repeatable method used to create the composites. Any tested formulation did not widely influence the Tg of the silicon, whereas the fillers increased the rigidity of the PDMS matrix, affecting the characteristic properties of the polymer itself. The nature of the filler affected the thermal conductivity. Among the metals tested, dendritic Cu returned the highest increment (reaching an increment of 300% with respect to the pristine polymer matrix). The volume filler influenced the thermal conductivity, obtaining the best results with the highest added volume filler. Moreover, the shape affected the thermal conductivity and the dimension of the particle influenced the result, in fact, considering the Ni case, larger particles showed a higher increase of thermal conductivity (the k was 150% higher that the pristine matrix). The CNT had an interesting result considering the introduced amount of filler with respect the other tested type.  
By this comprehensive investigation we could clarify the filler parameters which affect the thermal conductivity of the silicone composites. The best thermal behavior can be achieved by selecting the proper combination in terms of filler type, shape, dimension, and surface/volume ratio.  
**Supplementary Materials:** The following are available online at [[https://www.mdpi.com/article/10.3390/app11125663/s1](https://www.mdpi.com/article/10.3390/app11125663/s1)]([https://www.mdpi.com/article/10.3390/app11125663/s1](https://www.mdpi.com/article/10.3390/app11125663/s1)), Figure S1. ATR-FTIR for composite with spheroidal copper; Figure S2. ATR-FTIR for composite with smallest Ni particles; Figure S3. ATR-FTIR for composite with biggest Ni particles; Figure S4. ATR-FTIR for composite with BN; Figure S5. ATR-FTIR for composite with CNT; Figure S6. DMTA for composite with spheroidal copper; Figure S7. DMTA for composite with Ni particles; Figure S8. DMTA for composite with the largest Ni particles; Figure S9. DMTA for composite with boron nitride nanoparticles; Figure S10. DMTA for composite with CNT; Figure S11. DMTA for composite with carbon black nanoparticles; Figure S12. Thermocamera result for the composite with carbon nanotubes; Figure S13. Thermocamera result for the composite with Ni (large particles); Figure S14. Thermocamera result for the composite with Ni (small particles); Figure S15. Thermocamera result for the composite with dendritic Cu particles; Figure S16. Thermocamera curves for the composite with spheroidal Cu particles; Figure S17. Thermocamera result for the composite with carbon black; Figure S18. All curves compared with Sylgard measured with the thermocamera.  
Figure 9: Thermal diffusivity (\(\upalpha\)) of the different composite measured by Hot Disk.  
**Author Contributions**: Conceptualization, S.S., M.S. and A.T.; investigation, G.R., L.P. and S.L.; writing--original draft preparation, G.R., L.P., S.L., A.T., S.S. and M.S.; supervision, S.S. and M.S.; project administration, S.S. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the European Commission through the local agency Finipemonte within the project \"4 CUSTHER\" (Manunet call 2019), grant number MNET19/NMAT-3622.  
The authors declare no conflict of interest.