Thermo-responsive Carbon Nanomaterials: Synthesis And Applications

In recent years, carbon nanomaterials have been widely used in the field ofcatalysis, biological, medicine, electronic devices, etc., due to their unique structuresand properties. However, their insolubility and great tendency to agglomerate(micrometre-order) in water, which damaged the original nature by size, restrict theirextensive use. Therefore, carbon nanomaterials functionalization bystimuli-responsive polymers is an important means to enhance the dispersibility andendow the carbon nanomaterials with stimuli-sensitivity.Firstly, graphene oxide (GO) are covalent modified by Poly(N-isopropylacrylamide)(PNIPAAm), and GO–PNIPAAm hybrids were successfullyprepared via in situ freeradical polymerization. The hybrids have excellent solubilityat low temperature, and insoluble aggregates at high temperature will happen togetherThe structural reorganization behavior of GO–PNIPAAm is dependent on the watercontent in the GO–PNIPAM hybrids. Reversible switching of its wettability onexposure to NIR light was also demonstrated.However, this covalent functionalization method have several obstacles,including hardly-retained or even destroyed the structure of the original carbonnanomaterials, weak dispersibility against harsh conditions, narrowed applicationareas, etc. Therefore, we demonstrated a non-covalent functionalization method thatthermo-responsive polymer PNIPAAm-grafted dextran (DexPNI) is introduced tomodified carbon nanomaterials. These non-covalent functionalized carbonnanomaterials show excellent stability under various conditions, and the opticalproperties and aggregation behaviors can be smartly controlled by temperature andNIR light.Finally, on the basis of a study done before, we have successfully developed aunique graphene-based smart catalytic system which is consisted of graphenesupported Au-Pt bimetallic nanocatalyst with well defined core-shell structure anddextran-based temperature-responsive polymer. The unique catalytic system possessexcellent catalytic performances and temperature controlled catalytic behaviors. Thecatalytic activities of the system can be readily switched on or off at differenttemperature windows. Notably, considering the change in its catalytic activities is accompanied by the conformational transitions of the system, it may also possessadvantages over other common graphene-based catalysts in certain circumstances.