Controlled Preparation And Study Of Colloidal Nanocrystal Clusters Based On Star-like P4VP-b-PS As Nanoreactors

Colloidal nanocrystal cluster(CNC)is secondary structure formed by clustering nanocrystals,and may result in new properties different from individual nanocrystal due to the interactions between neighboring nanocrystals.Although there were several effective methods for preparing CNCs,it remained a challenge to synthesis uniform colloidal nanocrystal clusters with precisely dimension control.Here,we reported a general strategy for crafting a large variety of functional CNCs with precisely controlled dimensions,compositions and architectures,by using star-like block copolymer P4VP-b-PS as nanoreactors.The inner P4VP blocks could associate with metal precursors via strong coordination interaction and then be converted to yield nanocrystals.By regulating the amount of precursor and reaction time,the growth rate and region of individual nanocrystals were limited to form precisely controlled CNCs.The generality of the approach was demonstrated by the craft of metallic,magnetic and semiconductor CNCs of various sizes and structures.The work contents are as follows:(1)Synthesis and characterization of amphiphilic multi-arm star-like block copolymer P4VP-b-PSBy using atom transfer radical polymerization(ATRP),four amphiphilic multiarm star-like block copolymers P4VP-b-PS with different molecular weight of each block were prepared.Then,the star-like P4VP-b-PS was characterized by mulitiple characterization techniques,such as proton nuclear magnetic resonance,Fourier transform infrared spectroscopy,gel permeation chromatography,dynamic light scattering and transmission electron microscopy.The results showed that the polymerization process was well-controlled and thus the particle size distribution of star-like copolymer was uniform.By adjusting the polymerization time of 4VP monomer,the molecular weight of P4VP could be precisely controlled and then the particle size could be ajusted.(2)The research on the controllable preparation of Ag colloidal nanocrystal clusters(CNCs)by using star-like block copolymer P4VP-b-PS as nanoreactorBy using the multi-arm star-like block copolymer P4VP-b-PS as nanoreactor,as there was a strong coordination interaction between the pyridyl group in P4VP block and the metal ion in precursor,a series of Ag CNCs coated by PS chains were successfully prepared through in-situ reduction and growth.By using star-like P4VPb-PS with different molecular weights as nanoreactors,Ag CNCs with different sizes were prepared,which proved that the controllability of ATRP could be successfully extended to the controllable preparation of CNCs.In addition,the influence of the solvent(mixed solvent of tetrahydrofuran and toluene)on the morphology of the CNCs was determined,and the influence of the amount of precursor and the reduction process(including reduction time and the amount of reducing agent)on the morphology of the CNCs was studied.(3)Research on the generality for preparing CNCs by using multi-arm star-like block copolymer P4VP-b-PS as nanoreactorsThe multi-arm star-like block copolymer P4VP-b-PS was used to prepare Au CNCs,Cu2O CNCs,TiO2 CNCs,Fe3O4 CNCs,and CdSe CNCs as well as Au/Ag CNCs and Ag/Fe3O4 CNCs,proving the generality of preparing CNCs by using star-like block copolymer P4VP-b-PS as nanoreactor.Further,their corresponding properties such as surface enhanced Raman scattering,fluorescence,magnetism and other properties were studied.