Investigating Switchable Nanostructures in Shape Memory Process for Amphipathic Janus Nanoparticles

Janus particles (JPs) have attracted increasing attention from the communities of materials science, chemistry, physics, and biology. However, the nanoscale JPs that can switch shapes in response to an environmental stimulus is a significant challenge. In this article, we have demonstrated a simple procedure to fabricate the amphipathic Janus nanoparticles (JNPs) composed of hydrophilic body and hydrophobic lobe via using sudden negative pressure technique. Moreover, in response to temperature, the nanoparticles can recover to their initial nanosphere state by a switchable process, showing promising shape memory effect. Here, we can monitor the switchable nanostructures with hydrophilic and hydrophobic changes in the shape memory process of the JNPs by transmission electron microscope, dynamic light scattering, and water contact angle. Furthermore, we successfully compare the differences in shape deformation ratio and shape recovery ratio using the three test methods by the statistical analysis of Student's t-test for independent samples. In addition, we also develop hybrid magnetic Janus nanoparticles, changed from the amphipathic JNPs by the selective attachment of magnetic nanoparticles with hydrophobic molecules, which show new Janus nanostructure and shape memory property.