Improved Salt Spray Resistance of Silver-Plated SiO2 via Self-Assembled Mercapto Inhibitors

Highly conductive fillers are an essential raw material in the fabrication of conductive composites, paste, ink, adhesive, etc. Still, susceptibility to salt spray erosion remains a serious issue for silver-based fillers. Herein, we first prepared highly conductive silver-plated microspherical silica (Ag/pSiO2) through catechol/polyamine surface functionalization and subsequently formed a self-assembled inhibition layer on the surface of Ag/pSiO2 by using (3-mercaptopropyl)trimethoxysilane (KH590) to enhance the salt spray erosion resistance. The results suggested that the self-assembled KH590 greatly improved the salt spray erosion resistance of the Ag/pSiO2. The total shielding effectiveness (SEt) of the composites protected by KH590 was 106 dB after the salt spray erosion, which was even 16 dB higher than that before erosion. In contrast, the SEt of the composites without KH590 decreased significantly from 111 to 76 dB. Further studies revealed that the KH590 inhibitor strongly prevented the penetration of Cl– and subsequently enhanced the salt spray resistance. Considering the facile and effective preparation, this strategy could be applied in large-scale silver-based EMI shielding materials.