Multi-functional PDMS/MMT Coating on magnesium substrates: Hydrophobicity, durability, and EMI shielding

Abstract

In this work, a highly efficient surface coating strategy using polydimethylsiloxane (PDMS) modified low-cost montmorillonite (MMT) was revealed, to enhance the surface performance and durability of magnesium substrates. Contact angle, self-cleaning, wear resistance, corrosion resistance and ultrabroadband electromagnetic absorption and EMI shielding evaluations were comprehensively studied. The obtained PDMS/MMT/Mg substrate consistently exhibited an obvious increased contact angle from 76.1 to 141.9 °, signifying strong hydrophobicity and self-cleaning properties compared to the untreated R-Mg substrate. No significant surface wettability changes were detected even after 50 times of tape peeling or 3.0 wt% NaCl solution immersion for 60 h, indicating high durability of the protective PDMS/MMT coatings. Moreover, the PDMS/MMT/Mg substrates can be applied as microwave-absorbing materials, particularly in high-frequency applications, and as excellent EMI shielding with an SE value above 40 dB. This study highlights the effectiveness of the relatively inexpensive PDMS/MMT coating in enhancing the performance of magnesium substrates, providing a new approach to balance cost control and meet performance requirements in industrial or large-scale production.