Photo-crosslinkable, deformable PMMA colloids

Polymeric nano- and microparticles are finding widespread applications in materials and biological science. In all preparation methods pursued to date, the chemical stability of the particles is determined by the polymer system chosen. Usually, after particle synthesis, postprocessing with the aim of changing their stability is not possible. Therefore, one only has two choices: the synthesis of crosslinked polymer particles with high solvent and heat resistance and limited formability, or the synthesis of polymer particles consisting of linear polymer chains exhibiting low stability and high formability. In this contribution, we describe a new class of colloids which combine the advantages of both particle systems. The particles are composed of linear PMMA chains which are functionalized with photo-crosslinkable moieties. After preparation, the particles can be deformed before they are crosslinked by UV illumination. This offers unique possibilities for particle modification with a broad range of possible applications. Three examples are given. First, we show that the particles can be thermo-mechanically deformed into anisotropic shapes, in which they can be locked by subsequent crosslinking. Relaxation into the thermodynamically favorable spherical shape is thus suppressed, even in harsh environments. Second, we describe how the difference in solvent stability between illuminated and non-illuminated particles can be exploited for photolithography. Third, we demonstrate how photo-crosslinked anisotropic particles can be loaded with functional compounds, e.g. fluorophores.