## 3 Results and Discussion  
### Free Radical Polymerization (FRP)  
The polymerization of TMPTA smoothly proceeds at room temperature using DPSi/AgSbF\({}_{6}\) (2%/1% _w/w_) (Figure 1A); the stirring is stopped within 3 min due to the complete polymerization of the formulation. The polymerization does not occur using DPSi or AgSbF\({}_{6}\) independently thereby demonstrating that this combination is necessary to initiate the process. Almost no inhibition is noted as a short period is already requested for the solubilization of the silane into the formulation. A complete polymerization is obtained after about 300 s. It can be noted that the polymerization is dramatically faster under air than under argon (tack free time \(\sim\)3 min _vs._ 6 min, respectively, Figure 1A). This result shows that (i) no strong oxygen inhibition obviously occurs; and (ii) oxygen should positively participate in the initiation process (see below). Remarkably, a high Si-H consumption is observed during the polymerization (Figure 1B) confirming the hydrogen abstraction process (Schemes 2 and 3) (see below): This demonstrates that the Si-H conversion is directly related to the overall efficiency of the system. The formation of polyacrylate (PTMPTA) is well evidenced by IR spectra by the observation of the disappearance of the characteristic band of the acrylate double bonds at 1620 cm\({}^{-1}\) (Figure 1C) [10, 49]. Interestingly, the addition of NVK strongly improves the polymerization profiles, _i.e._, both the polymerization rate and the conversion are higher in the presence of NVK (the increase of the temperature is directly proportional to the monomer conversion [29, 48]) (Figure 2). A decrease of the tack free time is also noted (_i.e._, \(\sim\)1 min _vs._ 3 min with and without NVK, respectively). Remarkably, no polymerization is observed when using NVK/AgSbF\({}_{6}\) system in the same conditions (_i.e._, room temperature and under air). Consequently, the different three-component system (Silane/NVK/Silver salt) can be considered as excellent initiating system for thermal free radical polymerization under air and at RT (Figure 2). Figure 1: _Cont._However, the great interest of the proposed approach lies on the fact that the initiating system is efficient using simple glass vials and unpurified TMPTA, even in the presence of water or oxygen, which can act as polymerization inhibitors with other synthetic approaches [50]. This can open new opportunities for mass production and applications of PTPTA. Interestingly, when using a styrene monomer (St) instead TMPTA in the same experimental conditions, FRP occurs but the process is less efficient (e.g., inhibition time is high and tack free time \(\sim\)4 h using St _vs._ no inhibition time and 1 min using TMPTA) (Figure 3A). This can be related to the low viscosity of this monomer (0.762 cp) compared to that of TMPTA (70-100 cp), which increases the oxygen inhibition [33, 51]. The formation of polystyrene (PSt) is well evidenced by IR spectra of the obtained polymer (Figure 3B), which are fully consistent with the spectra that show the disappearance of the characteristic band of the acrylate double bonds at 1630 cm\({}^{-1}\). Remarkably, the  
Figure 1: **(A)** Role of the atmosphere in the free radical polymerization of TMPTA in the presence of DPSi/AgSbF\({}_{6}\) (2%/1% _w/w_): **(1)** under air and **(2)** under argon; **(B)** IR band of the decreasing of the DPSi recorded during the polymerization; and **(C)** real-time FT-IR spectra in the 1600–1670 cm\({}^{-1}\) wavenumber range of sample containing 1% (wt) of AgSbF\({}_{6}\) and 2% (wt) of DPSi in TMPTA under air **(1**- before and **2**- after polymerization). Figure 2: Comparison of the polymerization initiating ability under air and at RT of sample containing 1% (wt) of AgSbF\({}_{6}\) and 2% (wt) of DPSi in TMPTA: **(1)** without NVK and **(2)** with 2% (wt) of NVK. consumption of the silanes Si-H is almost complete (\(\sim\)100%) (Figure 3C). This is also found in agreement with the proposed mechanism (Schemes 1 and 2).