We present a facile and versatile
platform approach for the synthesis
of submicrometer-sized hybrid particles based on an oil-in-water emulsion.
These particles comprise organosiloxanes and/or organosilsesquioxanes
formed via hydrolysis and polycondensation of alkyl- or aryltrimethoxysilane,
and polystyrene or poly(methyl methacrylate) formed through radical
polymerization of styrene and methyl methacrylate, respectively. In
this synthesis, the alkyl- or aryltrimethoxysilane fulfills three
different roles: (i) it is part of the oil phase, (ii) serves as monomer
for the formation of the organosiloxane network, and (iii) forms a
surface active species that stabilizes the emulsion. Size, composition
and architecture of the resulting hybrid particles are programmable
in this synthetic approach, as demonstrated for the combination phenyltrimethoxysilane/styrene.
The versatility of the approach is demonstrated by preparing hybrid
particles based on following precursor/monomer combinations: phenyltrimethoxysilane/methyl
methacrylate, methyltrimethoxysilane/styrene, (3-acryloxypropyl)trimethoxysilane/styrene
and (3-mercaptopropyl)trimethoxysilane/styrene. Latter combination
yields hybrid spheres with thiol groups suited for further functionalization.
Protecting groups are commonly applied in multi-step molecular syntheses to protect one or multiple functional groups from reacting. After the reaction, they are removed from the molecule. In full analogy to this concept, we report the practical and scalable colloidal synthesis of Au semishells using polyphenylsiloxane protecting patches to prevent part of the surface of polystyrene nanoparticles from being covered with Au. After Au deposition, the patches are removed yielding Au semishells. We anticipate that this strategy can be extended to the synthesis of other types of non-centrosymmetric nanoparticles.
Reactive surfactants (surfmers), which are covalently attached to the surface of sub-micron sized polymer particles during emulsion polymerisation, are applied to tailor the surface functionality of polymer particles for an application of choice. We present a systematic study on the use of oligoglycidol-functionalised styrene macromolecules as surfmers in the emulsion polymerization of styrene. Firstly, we report the impact of the surfmer concentration on the particle size for polymerisations performed above and below the critical micelle concentration. Secondly, we report the influence of the oligoglycidol chain length on the particle size. Thirdly, we conducted experiments to analyse the influence of the surfmer concentration and its chain length on the colloidal stability of the aqueous polystyrene nanoparticles in sodium chloride solutions. We demonstrated that the size of polystyrene particles could be influenced by changing both the surfmer concentration and its chain length. Furthermore, we showed that the colloidal stability of the oligoglycidol-functionalized polystyrene particles is dependent on the particle size, and not directly related to the oligoglycidol chain length.
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