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

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

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Porous polymer or carbon particles with integrated functional nanoparticles are very interesting for many applications, like adsorption, catalysis and energy conversion. The preparation of polymeric microparticles in a size range down to 10 µm can be achieved via suspension polymerization. Particle sizes can be adjusted by the stirring speed and by the type and amount of the used stabilizer [1]. Using porogens as solvent for cross-linking copolymerization systems provides the possibility to obtain porous polymeric microparticles. The variation of the porogen has an influence on the pore size distribution and the specific surface area [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. 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 unmodified and hydrophobically modified titanium dioxide nanoparticles (P25 and 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 530 m²/g) and a good control of size (in the range of 50 µm) could be obtained. 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 materials. T805 nanoparticles can be activated by different treatments. Pyrolysis conditions are optimized to obtain porous carbon-based nanohybrid materials. These materials are also characterized comprehensively and tested with respect to their functionality in photocatalysis.

References

  1. M. Gokmen, F. Du Prez, Progress in Polymer Science 2012, 37, 365

Contact:
Prof. Mathias Ulbricht