Photo-responsive microcapsule systems via supramolecular chemistry

Abstract

Supramolecular self-assembly is a reversible process by which nanoparticles or other components spontaneously ordered into well organized functional structures due to their specific noncovalent interactions through their environment. These noncovalent interactions let the nano/micro-particles recognize each other and form different constructions such as micelles, microspheres, interface (membrane) or collodidal microcapsules. However, the construction of these systems requires a high degree of control to direct the nanoparticles‟ aggregation process. This thesis focuses on the formation and stabilization of self-assembled microcapsules that are obtained with noncovalent crosslinking interactions with an emphasis on photo-reversible ability of them. In this study, cyclodextrin functionalized gold nanoparticles and different photoswitchable crosslinker molecules were synthesized to obtain stimuli responsive colloidal microcapsules. Host-guest complexation between azobenzene molecule on the linker and cyclodextrin ligand on the nanoparticle surfaces leads to crosslinking of nanoparticles at the interface of water/organic-solvent emulsion. Resulting microcapsules were characterized using a variety of techniques such as optical microscopy, UV-Vis spectrometry and transmission electron microscope (TEM).