# Synthesis of Covalently Cross-Linked Colloidosomes from Peroxidized Pickering Emulsions
###### Abstract  
A new approach to the formation of cross-linked colloidosomes was developed on the basis of Pickering emulsions that were stabilized exclusively by peroxididized colloidal particles. Free radical polymerization and a soft template technique were used to convert droplets of a Pickering emulsion into colloidosomes. The peroxididized latex particles were synthesized in the emulsion polymerization process using amphiphilic polyperoxide copolymers poly(2-_tert_-butylperoxy-2-methyl-5-hexen-3-ine-co-maleic acid) (PM-1-MAc) or poly[N-(_tert_-butylperoxymethyl)acrylamide]-_co_-maleic acid (PM-2-MAc), which were applied as both initiators and surfactants (nisurfs). The polymerization in the presence of the insurfs results in latexes with a controllable amount of peroxide and carboxyl groups at the particle surface. Peroxidized polystyrene latex particles with a covalently grafted layer of inisurf PM-1-MAc or PM-2-MAc were used as Pickering stabilizers to form Pickering emulsions. A mixture of styrene and/or butyl acrylate with divinylbenzene and hexadecane was applied as a template for the synthesis of colloidosomes. Peroxidized latex particles located at the interface are involved in the radical reactions of colloidosomes formation. As a result, covalently cross-linked colloidosomes were obtained. It was demonstrated that the structure of the synthesized (using peroxididized latex particles) colloidosomes depends on the amount of functional groups and pH during the synthesis. Therefore, the size and morphology of colloidosomes can be controlled by latex particle surface properties. p pacs: 67.10. The phenomena of particle surface activity were first described by [PERSON] and [PERSON] [8; 9]. Several decades later, [PERSON] [10; 11] proposed a mechanism for the self-assembly of colloidal particles at the liquid-liquid interface. It was established that Pickering emulsions exhibit superior kinetic and thermodynamic stability compared to conventional emulsions. The stabilization mechanism of colloidal particles is based on the reduction of interfacial tension, which is similar to molecular surfactants; however, compared to surfactant molecules, colloidal particles are significantly larger, and that imparts specifics to the emulsification process and stability profile [12; 13]. Using a Pickering emulsion opens up a broad range of opportunities not only for improving the properties and performance of already existing polymer colloids but also for developing new polymer composite materials and nanomaterials [14]. Colloidal structures obtained as a result of fully or partially solidifying droplets of Pickering emulsion are generally referred to as colloidosomes. There are reports in the literature of the synthesis of various types of colloidosomes, including \"hairy\" colloidosomes [15], \"sensitive\" colloidosomes [16; 17], and \"carbon nanotubosomes\" [18]. The formation of covalently cross-linked colloidosomes via free radical and condensation polymerization mechanisms has been reported [19; 20; 21] to be an effective approach for the fabrication of various colloidosome morphologies, such as core-shell and capsule-like morphologies [20; 22]. Due to the ability to finely tune colloidosome properties (density of particle packing at the surface, shell thickness and porosity, core type, composition, etc. ), these structures can be engineered to efficiently encapsulate (absorb) and deliver (release) various cargos in a controlled fashion [23]. Reports have shown that colloidosomes can be employed as effective encapsulation tools for drug delivery or for the protection of components in the food and cosme industries [24; 25; 26; 27]. In this study, peroxid oxidized latex particles, i.e., latex particles with peroxide groups localized at their surface, were applied in the synthesis of cross-linked colloidosomes. The latexes were synthesized using amphiphilic polyperoxide copolymers that acted as initiators and surfactants (inisurf) simultaneously in the emulsion polymerization process.