Precisely Controlled Synthesis Of Nanocrystals Array With Star-like Diblock Copolymer As Nanoreactors

In recent decades,with the rapid development of nanocrystals science,in order to study the size effect of nanocrystals and explore their potential applications in nanotechnology,it is increasingly important to arrange nanocrystals in a certain pattern.Because of their excellent properties,nanocrystal arrays have wide application prospects in energy,electronics,optics and biological devices.Among the two kinds of preparation methods of nanocrystalline arrays,nano-etching technology cannot achieve large-scale continuous preparation of nanostructures due to its high cost.The templatebased nanomantronics has the advantages of low cost,simple process,easy crystal size control and wide applicability.The linear block copolymer(BCPs)self-assembly method,which contains two or more polymer segments with different chemical properties,has been proved to be a simple and effective strategy to fabricate highly ordered nanocrystal arrays,but it lacks stability and is susceptible to external conditions.In order to solve these problems,in this study,four batches of star-like β-CD-g-P4VPb-PS with different molecular weights were prepared by atomic transfer radical polymerization(ATRP)technique to meet the needs of various practical applications.This method had also been proved to be able to adjust the size and morphology of nanocrystals stably and accurately.In addition,the covalently stable monomolecular nanoreactor with predesigned nanostructures also provides a general method for the preparation of nanocrystal arrays,providing an effective alternative to the high-cost nanostructure array preparation technology.The details are as follows:(1)Four batches of 21-arms star-like block copolymer β-CD-g-P4VP-b-PS with different molecular weights were prepared using 8-cyclodextrin(β-CD)as the core and ATRP technology in sequence by adjusting the polymerization reaction time of different monomer 4VP and St.They were characterized by using a variety of effective characterization methods.The results demonstrated the successful preparation of the star-like polymer nanoreactors,the polymers were very pure and the polydispersity indexes were low.(2)The Ag clusters arrays with four different sizes were prepared by using starlike block copolymer nanoreactors,the prepared Ag clusters arrays were characterized by effective characterization methods,and the results proved that the diameters of the Ag clusters on the arrays were consistent with the sizes of the nanoreactors,reflecting the precise controllability of the nanoreactor.The effects of UV reduction time,spin coating parameters and the order of preparation process on the morphology of Ag clusters arrays were investigated.In addition,surface-enhanced Raman spectroscopy(SERS)and surface-enhanced fluorescence(SEF)properties of Ag nanocrystal clusters arrays with different sizes were studied.(3)Using 21-arms star-like block copolymer β-CD-g-P4VP-b-PS as nanoreactors,Au clusters array and PbTiO3(PTO)nanoparticles array were prepared respectively.The prepared nanocrystal arrays were characterized by effective characterization methods.The results showed that the preparation method of nanocrystal arrays by starlike block copolymer nanoreactors were universal,and their fluorescence and piezoelectric properties were also investigated respectively.