Preparation And Application Of A Class Of Polymer Functionalized Carbon Dots And Their Nanohybrids

Carbon dots?CDs?with excellent optical properties,chemical stability,water solubility,biocompatibility and low cytotoxicity,have triggered scientist's extensive research interests.Heteroatom doping not only can improve the optical properties,but also provide abundant functional groups on the surface of CDs for the further surface decoration.Inspired by Marine-mussels,the catechol groups of polydopamine from self-polymerization of dopamine could be coated onto many different substrates,which is a simple and green method for surface modification of CDs.Up to now,it has been reported by scientists that CDs can be decorated by inorganic substance,organic small molecules,biomacromolecules and polymer to improve their performance for the broader application fields.In this thesis,a series of studies for the construction and application of the polymer functionalized CDs have been carried out based on the mussel-inspired chemistry.The N doping CDs were prepared by high-temperature pyrolysis,and the catechol-terminated polymers were also synthesized to decorate the surface of CDs via the mussel-inspired chemistry.The polymers endowed CDs with different excellent properties,which expanded the applications of CDs in light emitting diode?LED?and catalysis fields.This thesis mainly includes the following two parts:In the first section,citric acid as carbon source and tri-hydroxymethyl aminomethane?Tris-HMA?as nitrogen source were utilized to synthesize water-soluble N doping CDs with blue light emission.The catechol-terminated hydrophobic polystyrene?PS?and hydrophilic poly(poly?ethylene glycol?methyl ether methacrylate?PPEGMA?were gained by a typical reversible addition-fragmentation chain transfer?RAFT?polymerization,and then grafted onto the surface of N-doping CDs under the weak base condition by mussel chemistry?called CD@PS and CD@PPEGMA?.We mainly explored the influence of the polymer functionalization on the optical properties of CDs and the effect of hydrophobic PS decoration on the solubility of CDs in organic phase.The results indicated that the polymer anchored CDs?CD/P?exhibited better optical properties in solid state compared with pure CDs.Especially,the introduction of hydrophobic PS could successfully transfer the hydrophilic CDs into non-polar organic solvents,which broadened the application range of water-soluble CDs.We also prepared the transparent polymer bulk nanohybrids with white-lightemissionbyintroducingtheblue-emittingCD@PS,and5-?2-methacryloyl-ethyloxymethyl?-8-quinolinol?MQ?coordinated CdSe/ZnS quantum dots?QDs?as green and red-light components in the polymerization process of styrene monomers.The resulted fluorescent nanohybrid was employed to fabricate cold WLED with CIE coordinate?0.32,0.31?and the correlated color temperature 6250 K.This inexpensive cold WLED has potential application value in indoor and outdoor lighting.In the second section,we successfully developed a facile strategy for the construction of Au NPs stabilized by thermo-responsive poly?N-isopropylacrylamide??PNIPAM?grafted carbon dots?Au@CD@P?for highly effective catalytic reduction reaction.Thermo-responsive PNIPAM can be easily anchored to CDs via mussel-inspired chemistry route.Au@CD@P nanohybrids were fabricated by in situ reduction route employing CD@P as stabilizing agent.Besides,the Au@CDs nanohybrids without polymers were also obtained without additional photo-irradiation or reducing agents,in which CDs played an important role in the reduction process,not only as reducing agents,but as stabilizers.We also investigated the catalytic performance of Au@CD@P and Au@CD nanohybrids as catalysts for the reduction of nitrophenol isomers.The results showed that the Au@CD@P and Au@CD nanohybrids as catalysts with excellent water dispersion and stability had highly catalytic activity for the reduction of nitrophenol isomers.Furthermore,the temperature-responsive PNIPAM chains in Au@CD@P₁ catalyst played a role as the switch,which can regulate the reaction rate by the temperature of catalytic systems.Au@CD@P also exhibited excellent recyclability,which provides a new avenue for the preparation of high performance catalysts through green chemistry.