**Appendix A**

**Table A1.** Number average molecular weights (Mn) and polydispersity indices (PDI) of Di-10, Di-50, Di-400, and C2T. The data were obtained by SEC and 1H NMR. The molecular weights obtained by SEC were used for the further calculation of the silicone elastomer network compositions.


**Figure A1.** SEC eluograms of HO-PDMS-OH (C2T) and (MeO)3Si-PDMS-Si(OMe)3 cross-linkers (Di-10, Di-50, and Di-400).


**Table A2.** Compositions of silicone elastomers for long-term stability tests.


\*

 Total mass 4 g, \*\* Total mass 0.5 g, \*\*\* Solution in toluene (0.81 g/mL).

**Table A3.** Compositions of silicone elastomers for tensile, electrical breakdown strength, and scratch resistance measurements.


\* Total mass 6 g, \*\* Total mass 4 g, \*\*\* Solution in toluene (0.76 g/mL).

**Figure A2.** An example of calculation of the extractable PDMS from E\_C2T+Di-50\_r1.5 after 1 day in a climate chamber.

**Figure A3.** An example of calculation of the extractable PDMS from E\_C2T+(QMH)8\_r15 after 1 day in a climate chamber.


**Table A4.** Amounts of extractable PDMS (determined by 1H NMR) and sol fraction (determined from the weight loss) of the stable elastomer films.

**Figure A4.** SEC eluogram of the sol fraction of a commercial coating (E\_Ref). The elastomer age was 27 days.

**Figure A5.** A schematic illustration of SEM sample preparation: (**a**) A double-sided tape was attached onto two plastic frames made of hard plastic. Two specimens 25 mm in length and 6 mm in width were cut from the elastomer film E\_C2T+(QMOEt)8\_r15. (**b**) One of the two specimens was attached to the frame in unstretched state. The other specimen was stretched by ~100% (a sufficient strain to observe the film opacity) before attaching to the frame. (**c**) To ensure a proper specimen attachment, the second plastic frame was placed facing down by the double side tape on the top of the setup.
