Preparation And Properties Of Janus Composite Nanoparticles

Janus composite nanoparticles have been gradually developed as a kind of nanoparticles with the asymmetric structure in last decade. More attention has been attracted on Janus nanoparticles with two distinct compositions due to their asymmetric characteristics in properties and shapes. As continuously explored the new nanoparticles, the relative applications in various fields are also gradually developed. Janus nanoparticles have potential applications in biological carrier,surfactant, optical probe; drive motor, catalyst and so on. Especially, AuNP-PS nanoparticles have been proved that they had a great potential in detector, biological sensor. But due to their special structures and small sizes, the research on the Janus nanoparticles is still on the stage of experiment, it is difficult to mass production. This work mainly focuses on the preparation and properties of(PEG)-AuNP-PS Janus composite nanoparticles. Janus composite nanoparticles have been synthesized successfully by three methods.1. This work put forward to synthesize Gold(AuNP)-Polystyrene(PS) Janus composite nanoparticles using one-step reverse atom transfer radical polymerization(RATRP) in emulsion for the first time. This method combined the advantages of RATRP in emulsion and seed growth, which could be used to mass production due to its simplicity. This work not only obtained Janus nanoparticles successfully, but also explored the optimal experimental conditions: the mole ratio of gold nanoparticles and styrene was 1/1.7×1010-1/3.1×109 in our experiment; added gold colloids into the system after the polymerization had been started for 2-10min; the system was conducted at 70 oC for 4h.2. AuNP-PS Janus composite nanoparticles have been prepared by surface initiated atom transfer radical polymerization(SI-ATRP) successfully. This method not only be used to prepare the core-shell structure composite nanoparticles, but also to synthesis the Janus nanoparticles by adjusting the ratio of gold nanoparticles and initiators. Besides, the structure of Janus nanoparticles is relatively stable. The workgot conclusion: Terminated thiol initiators were synthesized successfully;Initiator-coated gold nanoparticles were obtained through the bond of Au-S; The ratio of gold nanoparticles and initiators ranged from 1/1000 to 1/10000, AuNP-PS Janus composite nanoparticles could be obtained. It was preferred to obtain core-shell nanoparticles if the ratio decreased.3. The preparation of Polyethylene Glycol(PEG)-AuNP-PS Janus composite nanoparticles by single crystal template method has been studied. This method combined the advantages of masking method and “grafting to” method. Besides, the structures of Janus nanoparticles were stable. This work got conclusion: The single crystal of terminated thiol polyethylene glycol(HS-PEG) has been prepared successfully; AuNPs were immobilized on the surface of HS-PEG single crystal by the bond of Au-S; PEG-AuNP-PS Janus nanoparticles were obtained successfully through the research on the amphipathic nanoparticles gathered into different micelles.Meanwhile, the directed graph of Polymer guided aggregation of Janus block nanoparticles in different solvents was got.