Colloids, particles in the nanometer to micrometer size-range, are attractive building blocks for bottom-up approaches to new materials with new and technologically important properties. Whereas naturally occurring colloids can be any shape in principle – blood platelets are disc-shaped and viruses often rod-shaped, for example – artificial colloids are typically spherical. Unfortunately, the spherical shape limits the repertoire of structures that artificial colloids can organize into (compare to the stacking of oranges in the fruit market), and this severely hampers advances in the material science area. For this reason, scientists are trying to synthesize colloids with non-spherical shapes, which are expected to organize in much more exotic ways compare to spheres. Since structure and function are closely related, the resulting materials are expected to be empowered with new and interesting properties.
Among non-spherical colloids, so-called colloidal molecules have received much attention. Colloidal molecules are clusters of colloidal spheres, which have a shape reminiscent of that of real molecules. Analogous to the relationship between molecules and their constituent atoms, colloidal molecules are predicted to organize in more exotic ways compared to their spherical constituents.
In my research project, I design and synthesize colloidal spheres and develop methods for their assembly into colloidal molecules. My colloidal spheres are microgels, consisting of a water-swollen polymer network. Due to the choice of polymer – which is either PNIPAM or PNIPMAM – the microgels respond to changes in temperature. In particular, we benefit from the fact that the microgels’ interparticle interaction behavior changes with temperature: at temperatures below a certain threshold temperature (32 and 45 °C for PNIPAM and PNIPMAM, respectively) the particles experience repulsive interactions, whereas the interactions are attractive (associative) above this threshold. By using these microgels as building blocks, the resulting colloidal molecules inherit the temperature-dependent interactions, which provides control during their assembly into structures and materials.
Månsson, L. K., Immink, J. N., Mihut, A. M., Schurtenberger, P., & Crassous, J. J. (2015). A new route towards colloidal molecules with externally tunable interaction sites. Faraday discussions, 181, 49-69.
Crassous, J. J., Mihut, A. M., Månsson, L. K., & Schurtenberger, P. (2015). Anisotropic responsive microgels with tuneable shape and interactions. Nanoscale, 7(38), 15971-15982.
Huang, X., Borgström, B., Månsson, L., Persson, L., Oredsson, S., Hegardt, C., & Strand, D. (2014). Semisynthesis of SY-1 for investigation of breast cancer stem cell selectivity of C-Ring-modified salinomycin analogues. ACS chemical biology, 9(7), 1587-1594.