## 3 Results and Discussion
### St-Co-DVB Polymerization in the Presence of Surface-Modified SNps  
When Pickering emulsion polymerizations were performed using VBS surface-modified SNps with 1, 2, and 3 wt% DVB, two scenarios occurred during the polymerization runs. At 1 wt% DVB, copolymer hybrid microspheres with core-shell structures were prepared, as depicted in Figure 4. However, surprisingly, at 2 and 3 wt% DVB, the polymerizations led to the formation of hybrid monolithic structures. The SEM micrographs of these monoliths with bi-continuous morphology are exhibited in Figure 5.  
Figure 3: Schematic representation of polymerization via limited homogeneous coagulative nucleation. (**A**) Hydrophobic monomers and VBS dissolved in the emulsion aqueous phase where the SNps form a 3D network. (**B**) Oligomer formation in the presence of dissolved monomers. (**C**) Formation of primary polymer particles growing by monomer swelling. (**D**) Polymer microspheres partially covered by SNps. Because of the fact that the emulsion formulations differed solely in the DVB concentration, it has been inferred that the crosslinking agent has a predominant effect on the polymerization mechanisms. It has been shown that during the pre-emulsion preparation process, VBS is added to the silica colloidal suspension in order to enhance its affinity to the polymer matrix and to promote the formation of silica-armed polymer particles [47]. The VBS monomer has a bifunctional nature in our case. On the one hand, it interacts with the SNPs' aluminoid groups, and on the other hand, due to its vinyl group oriented toward the aqueous phase, it can polymerize [37; 47]. Both electrostatic and covalent interactions allow excellent affinity between SNPs and the polymer matrix. That being the case, as soon as the reaction is initiated, the free radicals, formed from the homolytic decomposition of APS, can react either with slightly soluble-in-water monomers or with VBS attached onto the SNPs' surface to form oligomers. If growing oligomers originate from monomers, their sulfate negative charges, provided by the APS radicals, will ensure their adsorption onto the highly positively charged VBS-SNPs [47; 58]. Therefore, at the early stage of the polymerization, regardless of the nature of the monomers, it can be considered that the polymerization initiates onto the SNPs, forming growing oligomer chains attached onto the SNPs' surface. These growing oligomer chains will then reach a critical size, inducing collapsing due to the poor solvent quality of water, thus forming multiple hydrophobic patches onto the SNPs [59; 60]. These patchy polymer particles are amphiphilic, as they are characterized by a hydrophilic inorganic core, surrounded by hydrophobic pinned micelles. Depending on their hydrophilic-hydrophobic balance, these amphiphilic SNPs can aggregate into different anisotropic structures [61; 62], which can effectively lead to  
Figure 4: TEM images of St-co-DVB microspheres obtained at 1 wt% DVB. Figure 5: SEM images of hybrid monoliths with bi-continuous morphology, (**A**) 2 wt% DVB; (**B**) 3 wt% DVB. the formation of hybrid polymer microspheres or monoliths, during the St-co-DVB polymerization. DVB, as a crosslinking agent, is recognized as interfering in the nucleation and coagulation process. Consequently, during the nucleation process, DVB, due to both its crosslinking character and its concentration effect, can affect the number of growing oligomer chains per SNp and the flexibility and the length of these growing chains [63; 64]. Therefore, amphiphilic SNps, with different hydrophilic-hydrophobic characters, can be obtained at the early stage of reactions, which may either self-associate, like micelles in the aqueous phase, or preferentially adsorb, at the monomer droplets' interface, to give rise to microspheres or monolith formation, respectively.