Surface Thiolation of Al Microspheres to Deposite Thin and Compact Ag Shells for High Conductivity

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• 作者：Yilong Wang ; Jianghong Wen ; Suling Zhao ; Zhihong Chen ; Ke Ren ; Jie Sun ; Jianguo Guan
• 刊名：Langmuir
• 出版年：2015
• 出版时间：December 15, 2015
• 年：2015
• 卷：31
• 期：49
• 页码：13441-13451
• 全文大小：627K
• ISSN：1520-5827

文摘

In this work, we have demonstrated a method for controllable thiolated functionalization coupled with electroless silver plating to achieve aluminum@silver (Al@Ag) core鈥搒hell composite particles with thin and compact layers. First, Al microspheres were functionalized by a well-known polymerizable silane coupling agent, i.e., 3-mercaptopropyltrimethoxysilane (MPTMS). Decreasing the ethanol-to-water volume ratio (F) in silane solution produces modification films with high content of thiol groups on Al microspheres, owing to the dehydration of silane molecules with hydroxyl groups on Al microspheres and self-polymerization of silane molecules. Then, ethanol was used as one of the solvents to play a major role in the uniform dispersion of silane coupling agent in the solution, resulting in uniformly distributing and covalently attaching thiol groups on Al microspheres. In electroless silver plating, thiol groups being densely grafted on the surface of Al microspheres favor the heterogeneous nucleation of Ag, since the thiol group can firmly bind with Ag⁺ and enable the in situ reduction by the reducing reagent. In this manner, dense Ag nuclei tend to produce thin and compact silver shells on the Al microspheres surfaces. The as-obtained Al@Ag core鈥搒hell composite particles show a resistivity as low as (8.58 卤 0.07) 脳 10^鈥? 惟路cm even when the Ag content is as low as 15.46 wt %. Therefore, the as-obtained Al@Ag core鈥搒hell composite particles have advantages of low weight, low silver content and high conductivity, which could make it a promising candidate for application in conductive and electromagnetic shielding composite materials.