# Synthesis of Covalently Cross-Linked Colloidosomes from Peroxidized Pickering Emulsions
## 3 Results and Discussion
### Synthesis and Characterization of Pervidized Latexes
During thermolysis, the peroxide groups decompose to form _tert_-butoxy and macroradicals, which are able to initiate radical reactions of styrene polymerization [28; 34]. Figure 4: Insurf formation by hydrolysis of an amphiphilic PM-2-MA copolymer at different pH levels (blue and orange represent the hydrophilic and hydrophobic moieties of PM-2-MA, respectively). The combination of the PM-1-MAc and PM-2-MAc macroradicals with the growing polystyrene chains leads to the attachment of the PM-1-MAc and PM-2-MAc macromolecules to the surface of latex particles and to the formation of the polyperoxide PM-1-MAc and PM-2-MAc layers covalently grafted to the polystyrene particle surface (Figure 3). The emulsion polymerization of styrene in the presence of PM-1-MAc resulted in polystyrene latex particles with peroxid oxidized surfaces and average diameters in the range of 165 nm to 220 nm (Table 1). The presence of the peroxide groups in the grafted PM-1-MAc macromolecules was proven by the thermogravimetric analysis of the polystyrene latex. Weight loss at 150-220 \({}^{\circ}\)C accompanied by a well-pronounced exothermic effect is characteristic of the decomposition of the ditertiary peroxide groups of PM-1 [28; 31; 35]. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{\begin{tabular}{c} **Sample of the** \\ **Peroxidized Late** \\ **Particles** \\ \end{tabular} } & \multicolumn{2}{c}{\
\begin{tabular}{c} **Synthetic Conditions for Perooxidized Latees** \\ **(Latex Particles)** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **\(D_{\text{h}}\)** \\ **(mm) 2** \\ **a Sample (\%) 3** \\ \end{tabular} } \\ \cline{2-5}  & **Initial [PM-1-MAc]** & \(T\) & **Conversion** & **(\%) 1** & **a Sample (\%) 3** \\ \hline polySt-PM-1-MAc-1 & 6 & 70 & 97 & 181 & 3.2 \\ polySt-PM-1-MAc-2 & 8 & 70 & 98 & 180 & 3.2 \\ polySt-PM-1-MAc-3 & 10 & 70 & 97 & 166 & 2.8 \\ polySt-PM-1-MAc-4 & 6 & 80 & 99 & 212 & 2.6 \\ polySt-PM-1-MAc-5 & 8 & 80 & 97 & 207 & 2.8 \\ polySt-PM-1-MAc-6 & 10 & 80 & 98 & 218 & 1.7 \\ \hline \hline \end{tabular}  
Notes: 1 Using solid content determination; 2 Using dynamic light scattering; 3 Using gas-liquid chromatography.  
\end{table} 
Table 1: Physico-chemical characteristics of latex particles synthesized using varying concentrations of PM-1-MAc in the emulsion polymerization of styrene at pH 10. Figure 3: Emulsion polymerization of styrene using PM-1-MAc and PM-2-MAc as polymeric inisurfs. The ratio of the low-molecular-weight products (i.e., acetone and 2-methyl-2-propanol) of the peroxide group decomposition (Scheme 5) was determined using gas-liquid chromatography, which enabled quantifying the PM-1 units in the peroxididized polystyrene latex (Table 1). The presence of the PM-1-MAc chains in the polystyrene latex confirms a covalent grafting of the PM-1-MAc macromolecules to the surface of the polystyrene latex particles. Varying concentrations of the synthesized PM-2-MAc copolymer were used in a series of emulsion polymerizations of styrene at pH 9.5 (Table 2). The expectation was that the PM-2-MAc would act as an insiurf during the polymerization process, initiating polymerization by generating free radicals at elevated temperatures and ensuring micelle formation and the stabilization of growing polymer particles. Figure 4A illustrates the size variations of the peroxididized particles obtained at 85 \({}^{\circ}\)C as a function of pH and initial PM-2-MAc concentration. In general, the size of latex particles decreases with an increasing PM-2-MAc concentration and with a decreasing pH. The latter can be explained by the fact that a higher concentration of insiurf naturally results in a larger number of micelles (nucleating sites for particle growth in emulsion polymerization); thus, a greater number of smaller particles is formed. The HLB of insiurf macromolecules depends on the pH of the solution. At a higher pH, insiurf macromolecules are more hydrophilic, and thus more are required to form a micelle (the opposite is true for a lower pH).