Stimuli-Responsive Polymer-Ligated Nanoparticles and Nanorods—From Self-Assembly to Tailored Optical and Catalytic Properties

In this talk, I will discuss a unique amphiphilic-nonlinear-block-copolymer-nanoreactor strategy for crafting stable hairy nanocrystals (nanoparticles (NPs) and nanorods (NRs)) with light- as well as thermal-promoted reversible and reliable self-assembly and tunable optical and catalytic properties. The size and shape of hairy nanocrystals can be precisely tailored by modulating the length of inner hydrophilic block of nonlinear block copolymers. The permanent anchoring of stimuli-responsive polymers on the nanocrystal surface renders the attractive feature of self-assembly and disassembly of nanocrystals on demand using stimuli of different wavelengths of light or temperature. In the first study, photo-responsive polymer-ligated noble metal NPs and NRs display tunable surface-plasmon resonance absorption and the reversible transformation of NPs and NRs between their dispersed and aggregated states. In the second study, thermo-responsive polymer-ligated noble metal NPs manifest controllable catalytic activity in nonmonotontic (i.e., non-Arrhenius-type dependence on temperature) or on/off (i.e., effectively switched “on” and “off” catalysis over temperature) manner over a broad region of temperature. By extension, this strategy enables the crafting of a family of stable stimuli-responsive nanocrystals and their assemblies for fundamental research in self-assembly and crystallization kinetics of nanocrystals as well as potential applications in optics, optoelectronics, magnetic technologies, sensory materials and devices, catalysis, nanotechnology, and biotechnology.