Controlled Shape Transformation and Loading Release of Smart Hemispherical Hybrid Microgels Triggered by ‘Inner Engines’

The dynamic controlling and changing the shape of microgels, especially the anisotropic change, remains a challenge for the construction of advanced smart materials. To this end, the fabrication of hemispherical hybrid microgels (HHMs) with Au nanorods(AuNRs)-based vesicles was demonstrated, with the thermo- and NIR light-triggered anisotropic shape transformation and controlled release induced by ‘inner engines’. AuNRs-based vesicles acting as ‘inner engines’ were first fabricated by the self-assembly of thiol-terminated block copolymers modified AuNRs, with the absorbance of NIR light (808 nm), thus generating heat in the system; second, poly(N-isopropyl acrylamide) (pNIPAM)-based HHMs containing AuNRs-based vesicles were synthesized by the assistance of both microfluidics and photopolymerization. Importantly, uneven heat generated by the gradationally distributed AuNRs-based vesicles in the hybrid microgels could cause an anisotropic shape change from hemispherical to mushroom-like shape via external stimuli, with good reversibility and reproducibility. Based on this, the controlled release of loadings (e. g. Rhodamine B (RhB)) inside the engines of the microgels can be realized by combining NIR light irradiation and the shape transformation. Thus, HHMs with AuNRs-vesicle-based engines provide a novel platform for the investigation of drug release, artificial actuators, and micromotors.