Cyclodextrin Stable Of Star Polymer Synthesis Of Nano-gold And Silver Sol

The metal colloids have the unique physical and chemical properties that are neither those of bulk materials nor those of molecular compounds.They have been exploited for the extensive potential applicationsinoptics,electronics,magnetic,catalyst,sensing,biomedicine,etc.The development of simple and versatile methods for the preparation of nanoparticles in a size-or shape-selected and-controlled manner is an important and challenging task.Star polymers are characterized as structures in which all the chains of a molecule are linked together to a small-molar-mass core.More recently,star polymers see increasingly widespread application in nanotechnology.As a consequence,the design and synthesis of the multi-armed star polymers as well as their functionalities in materials are highly sought after.β-Cyclodextrins(β-CDs) are a series of cyclic oligosaccharides composed of glucose units linked byα-1,4 linkage.They have polar hydrophilic outer shells and hydrophobic cavities. Furthermore,becauseβ-CDs possesses many hydroxyl groups,it should be used for conforming star polymers as well.It is well known that poly(dimethylaminoethyl methacrylate)(PDMAEMA) can undergo a conformational transition due to hydrophobic or hydrophilic molecular chain interactions by varying pH value and temperature.So dimethylaminoethyl methacrylate star polymers with cyclodextrin core(CD-PDMAEMA) were synthesized and it can be expected to obtain better results in the synthesis of metal colloids materials with the multi-armed star polymers.Based on the above,the recent development of metal colloids and synthesis of star polymers were simplely introduced,and the synthesis of CD-PDMAEMA were achieved by atom transfer radical polymerization.Gold and silver colloids were also prepared successfully at ambient temperature with CD-PDMAEMA.The main results obtained in this thesis are as follows.1.The synthesis of CD-PDMAEMA has been achieved successfully by atom transfer radical polymerization in aqueous acetone at ambient temperature using CuCl as catalyst,o-phen as a ligand reagent andβ-CD-Br as the initiator,respectively.The influence of different reaction time on the polymerization were studied.GPC results confirmed CD-PDMAEMA have low polydispersity (Mw/Mn＜1.10).The star polymer was characterized by FT-IR and ¹H-NMR.2.Gold colloids were prepared by reducing aqueous solutions of HAuCl₄ at ambient temperature with CD-PDMAEMA,which acted as both reducing and stabilizing agents for the formation of gold nanoparticles.The product was characterized by UV-Vis spectrum,FT-IR,XRD, SAED,TEM and DLS.It was also found that N/Au mole ratio and pH was the very important factor in preparating gold colloids.The size of gold nanoparticles could be controllable by the change of N/Au mole ratio and pH in aqueous solution.N/Au=6:1 and pH=7～11 is the best experiment condition.3.Silver colloids were prepared by reducing aqueous solutions of AgNO₃ at ambient temperature with CD-PDMAEMA,which acted as both reducing and stabilizing agents for the formation of silver nanoparticles.The product was characterized by UV-Vis spectrum,FT-IR and TEM.It was also found that N/Ag mole ratio and pH was the very important factor in preparating silver colloids.The size of silver nanoparticles could be controllable by the change of N/Ag mole ratio and pH in aqueous solution.N/Ag=6:1 and pH=7～10 is the best experiment condition.