Porous polymer- and carbon-based nanohybrid microparticles via suspension polymerization

Hanna Thierfeld, Universität Duisburg-Essen und NanoEnergieTechnikZentrum, Duisburg, Germany
Mathias Ulbricht, Universität Duisburg-Essen, Essen, Germany

Porous polymer or carbon particles with integrated functional nanoparticles are very important for many applications like catalysis, energy storage and energy conversion. The preparation of polymeric microparticles in a size range down to 10 µm can be achieved via suspension polymerization. Using porogens, it is possible to obtain porous polymeric microparticles. Polymer particle sizes can be adjusted by the stirring speed and by the type and amount of the used stabilizer [1]. For preparation of nanohybrid materials, the porogens should be good dispersants for the nanoparticles to achieve their homogenous distribution in the resulting polymer matrix. Furthermore, the variation of the porogen has an influence on the pore size distribution and the specific surface area [2]. To obtain carbon-based nanohybrid materials, the resulting material has to be suitable for carbonization by pyrolysis.

Using styrene and divinylbenzene as monomers, and cyclohexanol as porogen and dispersant for hydrophobically modified titanium dioxide nanoparticles (T805, Evonik) in suspension polymerization, it was possible to integrate the nanomaterial into the resulting polymeric microparticles. By optimizing the conditions, well-defined porous cross-linked polystyrene microparticles with high specific surface area (up to 420 m²/g) and a good control of size (in the range of 50 µm) could be obtained. The integration of unmodified titanium dioxide (P25, Evonik) was achieved by using a porogen mixture of toluene and 2-butanol. The obtained materials were also characterized by elemental analyses, scanning and transmission electron microscopy, and thermogravimetric analyses under different conditions. P25 nanoparticles have photocatalytic activity, which was tested by decomposition of an organic dye as model compound and found to be preserved after their incorporating into the polymer material. Furthermore, pyrolysis conditions have been optimized to obtain porous carbon-based nanohybrid material. These materials have also been characterized comprehensively and will be tested with respect to their functionality in photocatalysis.

[1] M. Gokmen, F. Du Prez, Progress in Polymer Science 2012, 37, 365-405.
[2] M. Mohamed, L. Wilson, Nanomaterials 2012, 2, 163-186.

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