Self-assembly is emerging as a superior method to prepare adaptive and responsive nanomaterials. In this contribution, we will highlight our newest findings concerning the preparation of photoresponsive and magnetoresponsive materials by self-assembly. These materials are photoresponsive since the particles interact through photoresponsive host-guest interactions of cyclodextrins and azobenzenes. Moreover, they are magnetoresponsive since they contain superparamagnetic nanoparticles.<br/>We have prepared “magnetic vesicles” that self-assemble in microscale linear aggregates in a magnetic field. A noncovalent and photoresponsive cross-linker can stabilize the metastable linear aggregates, which can be photoisomerized between an adhesive and a nonadhesive configuration. Thus, the hybrid material responds to magnetic field as well as to light and a stable self-assembled structure can only be obtained in a magnetic field in the presence of the noncovalent cross-linker.<br/>Furthermore, we explored arylazopyrazoles (AAPs) as a new light-responsive motif. Compared to azobenzenes, AAPs offer quantitative photoisomerzation in both directions and longer half-life times of the E-isomer. Derivatives of AAPs were readily synthesized enabling easy post-functionalization and water solubility. AAPs were applied in photoresponsive clustering of nanoparticles. Moreover, we have prepare Janus silica particles (diameter 6 micron) by sandwich microcontact printing of an ATRP initiator and subsequent growth of polymer brushes exclusively in the printed caps of the Janus particles. Moreover, we have shown that AAPs can be included in the polymer brush caps, and that the resulting ”guest” Janus particles form linear aggregates in the presence of superparamagnetic “host” nanoparticles coated with cyclodextrins. These anisotropic aggregates can be manipulated with a magnetic field.<br/>

Photo- and magnetoresponsive self-assembly of nanoparticles

253rd National Meeting (2017)

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