## 3 Results and Discussion
### Reaction Mechanisms  
The formation of a silyl radicals (R\({}_{3}\)Si\({}^{\bullet}\)) and/or silylium cations (R\({}_{3}\)Si\({}^{+}\)) through the interaction of the silane with silver salt is assumed (Scheme 2) by analogy with the reported behavior of R\({}_{3}\)SiH/AgCl\({}_{4}\) in organic chemistry [54; 55; 56; 57]. These reactions might proceed by an attack of the electrophile on a Si-H bond [54; 55; 56; 57]. On the other side, the formation of silylium cations when using chlorosilanes (R\({}_{3}\)SiCl) instead of R\({}_{3}\)SiH with silver salts (r'1) was well characterized [58]. The good polymerization ability of the R\({}_{3}\)SiH/AgSbF\({}_{6}\) and R\({}_{3}\)SiH/AgSbF\({}_{6}\)/NVK systems appears here as in full agreement with the formation of R\({}_{3}\)Si\({}^{\bullet}\), NVK\({}^{\bullet}\), R\({}_{3}\)Si\({}^{+}\), NVK\({}^{+}\) and H\({}^{+}\), which are largely known [16; 17; 43; 44; 45; 59; 60; 61; 62] as efficient initiating species for both thermal and photochemical radical and/or cationic polymerization of TMPTA and EPOX.  
Scheme 2, however, does not account for the favorable oxygen effect. The mechanism (Scheme 4) involves the oxidation of the silyl radical into a peroxyl, a rearrangement of the peroxyl (as already observed elsewhere) [63] and the further re-generation of a silyl radical together with the formation of R-SiH(O-R)\({}_{2}\). Such a process was already reported in [63; 64].  
Upon addition of NVK, R\({}_{3}\)Si\({}^{\bullet}\) react with the NVK double bond leading to R\({}_{3}\)Si-NVK\({}^{\bullet}\) (r'2), as known in other systems [59; 60; 61; 62]. As previously discussed [59; 60; 61; 62], R\({}_{3}\)Si-NVK\({}^{\bullet}\) radicals are easily oxidized by Ag\({}^{+}\) leading to the formation of R\({}_{3}\)Si-NVK\({}^{+}\) (r3) [65; 66]. R\({}_{3}\)Si-NVK\({}^{\bullet}\) is characterized by a very low ionization potential [60]; this is fully consistent with the associated fast oxidation process.  
The R\({}_{3}\)Si-NVK\({}^{\bullet}\) and R\({}_{3}\)Si-NVK\({}^{+}\) being a highly efficient initiating structure for the FRP and ROP of an acrylate and an epoxy [59; 65; 66; 67], it is not surprising that an efficient polymerization is found in the presence of NVK.  
In these reactions, radicals and cations are probably generated to initiate the free radical polymerization (FRP), ring opening polymerization (ROP) and interpenetrated polymer network (IPN) of the acrylate, epoxy and acrylate/epoxy blend monomers (r4), respectively, with _in-situ_ formation of silver nanoparticles (Ag(0)NPs) during the polymerization process (see above). Other elegant initiating systems based on other radical oxidation processes by Ag\({}^{+}\) were proposed in ref [68; 69; 70; 71; 72; 73; 74; 75].  
\[\text{R}_{3}\text{SiCl}+\text{AgSbF}_{6}\rightarrow\rightarrow\rightarrow \text{R}_{3}\text{Si}^{+}\text{SbF}_{6}{}^{-}+\text{Ag}(0)+\text{products}\] (r'1)  
\[\text{R}_{3}\text{Si}^{\bullet}+\text{NVK}\rightarrow\text{R}_{3}\text{Si-NVK}^{\bullet}\] (r'2)  
\[\text{R}_{3}\text{Si-NVK}^{\bullet}+\text{Ag}^{+}\rightarrow\text{R}_{3} \text{Si-NVK}^{+}+\text{Ag}_{(0)}\] (r3)  
\[\text{R}_{3}\text{Si-NVK}^{\bullet},\text{R}_{3}\text{Si}^{\bullet}+\text{ acrylate}\rightarrow\text{Polymer}\] (r4a)  
\[\text{R}_{3}\text{Si-NVK}^{+},\text{R}_{3}\text{Si}^{+},\text{H}^{+}+\text{epoxy} \rightarrow\text{Polymer}\] (r4b)