聚氧乙烯类表面活性剂体系中银纳米颗粒的合成

Synthesis of Silver Nanoparticles in Nonionic Surfactant System*

将 AgNO3水溶液与非离子表面活性剂 AEO- 7按一定比例混合，即可形成六方液晶 .体系中的 Ag＋被表面活性剂分子 AEO- 7还原成 Ag，形成 Ag的纳米颗粒 .在这一过程中，非离子表面活性剂液晶既是还原剂，又是反应介质和稳定剂 .在合成过程中，聚氧乙烯类表面活性剂的乙氧基形成了氢过氧化物，从而具有了将 Ag＋还原成单质 Ag的能力 . Ag纳米颗粒生长到一定时间不再继续变大，这表明颗粒的长大是靠自身的生长，并不发生颗粒聚集 .控制液晶体系中反应物的浓度、含量以及反应时间可得到不同大小的 Ag纳米颗粒 .所形成的 Ag纳米颗粒的平均粒径一般小于 10 nm.

Silver nanoparticles can be synthesized in liquid crystal systems formed by nonionic surfactant AEO-7 and AgNO3 aqueous solution. The surfactant AEO-7 acts as both reductive and protective agent in the synthetic process. In the system of surfactant with ethoxyl groups, it is believed that ethoxyl groups can form hydroperoxides, and these hydroperoxides endow the surfactant the ability of reduction. The effects of reaction time, concentration, temperature and the characters of the liquid crystal system have all been studied. Silver nanoparticles stop growing with the prolonging of reaction time to certain period. This indicates that the particle' s enlarging is due to self-growing process, but not aggregating of particles. And the average diameters of silver particles obtained are all smaller than 10 nm.