纳米金掺杂中空微胶囊的制备与表征

将表面含有双键的二氧化硅微粒分散在纳米金和聚乙烯吡咯烷酮溶液中.在此溶液中以聚乙烯吡咯烷酮为模板聚合物进行丙烯酸的模板聚合,得到二氧化硅为核、聚丙烯酸/聚乙烯吡咯烷酮/纳米金为壳层的核壳结构微粒.用氢氟酸将二氧化硅微粒去除后,得到了纳米金粒子掺杂的微胶囊.分别用扫描电子显微镜和激光共聚焦显微镜表征了微胶囊在干态和湿态下的形貌.通过电子衍射和透射电子显微镜确证了纳米金粒子在微囊壁上的存在和分布.

FABRICATION AND CHARACTERIZATION OF GOLD NANOPARTICLES LOADED MICROCAPSULES

A convenient method was developed to fabricate gold nanoparticles loaded microcapsules in one step and with high efficiency.First of all,the gold colloidal solution was prepared through reduction of AuCl~-_4 ions with NaBH_4 under stirring,and poly(vinylpyrrolidone)(PVP) was added quickly under severe agitation to prevent the aggregation of the gold nanoparticles during the dialyses.The gold nanoparticles in the colloidal solution had a diameter of about 7 nm and had a maximum absorption at 516 nm.Next,template polymerization of acrylic acid(AA) in the presence of PVP and 3-(trimethoxysilyl) propyl methacrylate(MPS) modified silica particles was carried out in the gold colloidal solution.The polymerization was initiated by K_2S_2O_8 and maintained for about 2 h under nitrogen atmosphere.After polymerization,the resulting composite particles were separated from the dispersion through centrifugation and were washed with triply-distilled water for several times.Finally,the gold nanoparticle-loaded microcapsules were obtained after core-removal with HF.In this process,the pre-adsorption of the complex of PVP/AA onto the gold nanoparticles made the nanoparticles polymerizable with free AA monomers during the template polymerization,and the gold nanoparticles doped PAA/PVP complex films were formed on the surfaces of the silica particles.After the core-removal process,the hollow nature and the integrity of the obtained microcapsules in both dry and wet states were demonstrated by scanning electron microscopy and confocal laser scanning microscopy,respectively.The entrapment of the gold nanoparticles in the capsules was confirmed by transmission electron microscopy.Electron diffraction pattern of the nanoparticles-loaded microcapsules showed the gold polycrystalline diffraction rings,from which the lattice constant of crystal plane {1 1 1} was calculated as 0.4174 nm,further confirming the existence of the gold nanoparticles.The gold nanoparticles were distributed uniformly in the microcapsule shells with no sign of aggregations.The amount of nanoparticles loaded in the microcapsule shells could be tuned by the concentration of the gold colloidal solution,(i.e.)higher concentration resulted in microcapsules with larger amount of gold nanoparticles in the shells.This process can be extended to other types of nanoparticles and polymers,thus can be widely applied to obtain composite microcapsules with desired functions.