以硝酸银为银源、间苯二酚为还原剂、聚乙烯吡咯烷酮为保护剂通过化学还原法制得纳米银颗粒,通过离心洗涤等操作洗掉多余的反应物,将其分别超声分散于水、无水乙醇和乙二醇中获得0.2 Wt%不同体系的纳米银溶胶.利用激光粒度分析仪、透射电子显微镜、扫描电子显微镜和同步热分析仪对纳米银颗粒进行表征并测定纳米银溶胶中的银含量.激光粒度分析仪的粒度分析结果表明,实验制得的纳米银颗粒的粒径在100 nm左右,且粒径分布均一.透射电子显微镜和扫描电子显微镜的结果进一步证实纳米银颗粒的粒径在纳米尺度范围且粒径均匀.采用Turbiscan多重光散射法研究了不同体系纳米银溶胶的分散稳定性,分析了导致纳米银溶胶不稳定的主要因素.研究发现:影响纳米银溶胶分散稳定性的主要因素包括颗粒粒径的变化和颗粒的迁移.对于水相体系,样品池中间部分背散射光强度随时间变化不大,样品池底部和顶部背散射光强度有较大变化,说明其稳定性的主要影响因素是纳米银颗粒的迁移,颗粒粒径变化影响不大;对于乙醇和乙二醇体系,样品池中间部分、底部和顶部的背散射光强度均有明显变化,说明颗粒粒径的变化和颗粒的迁移对体系稳定性均有一定程度的影响;最后通过比较三个体系的稳定性动力学指数,得到体系稳定性由高到低依次为乙二醇、水和乙醇。

Nano-silver particles were synthesized through chemical reduction method,using silver nitrate,m-dihydroxybenzene and polyvinylpyrrolidone as silver source,reduction agent and protective agent respectively;and redundant reactants were removed through centrifugation and washing operation.Then different nano-silver colloids were acquired by dispersing the nano-silver particles in water,ethanol and ethylene glycol respectively through ultrasonic dispersion.For comparison,the nano-silver particles mass fraction of all the colloids was 0.2 Wt% during the research.Nano-silver particles were characterized by laser particle size analyzer,transmission electron microscopy(TEM) and scanning electron microscopy(SEM);and the concentration of nano-silver colloids was confirmed through synchronized thermal analyzer(STA).The size distribution result of laser particle size analyzer showed that nano-silver particles were about 100 nm and had uniform size distribution.The images of TEM and SEM showed that the size of nano-silver particles was in nanoscale as well.To evaluate the dispersion stabilities of different nano-silver colloids,Turbiscan optical analyzer which was based on multiple light scattering analysis had been employed in the research;and the principle factors leading to instabilities of nano-silver colloids were also discussed.Results showed that particle size variation and particle migration were major factors which affected the dispersion stabilities of nano-silver colloids.For the nano-silver colloid dispersed in water phase,the backscattering light signal in middle of the sample cell stayed unchanged with time while the backscattering light signals at top and bottom of the sample cell showed dramatic variation during the measurement,which indicated that particle migration was the main reason why the nano-silver colloids was unstable.But for the nano-silver colloids dispersed in ethanol and ethylene glycol phase,the backscattering light signals in bottom,middle and top of the sample cell presented obvious variation at the end of the tests,which certificated that both particle size variation and particle migration affected the stabilities of nano-silver colloids.At last,by comparing the Turbiscan Stability Index(TSI) of three different nano-silver colloids,the stabilities of the systems were outlined by a descending order:ethylene glycol,water and ethanol.