**4. Conclusions**

To summarize, D3 is the cyclosiloxane of choice to generate silicone dispersions of very high molar mass polymers, a priori not reachable neither by conventional polycondensation in microsuspension nor emulsification. The fact that this monomer performs polymerization in almost all the catalytic systems screened here opens large avenues in the search for the ideal polymerization process that would hopefully not produce small cycles, such as D4 and D5, now targeted in the 'Registration, Evaluation and Authorisation of Chemicals' (REACh) European regulation.

**Author Contributions:** Conceptualization, F.G.; methodology, Q.B., C.L. and F.G.; formal analysis, C.L. and F.G.; writing—original draft preparation, Q.B. and C.L.; writing—review and editing, F.G. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Not applicable.

**Data Availability Statement:** The data presented in this study are available on request from the corresponding author.

**Conflicts of Interest:** The authors declare no conflict of interest.

**Sample Availability:** Samples are not available.
