Amino acid-modified polysiloxane for superior metal bonding and antimicrobial coatings

The development of high-bond strength polysiloxane adhesives has faced challenges due to limitations in adhesive strength and cohesion. To address this issue, the present study introduced a biobased N-acetyl-L-cysteine (NACL) modified polysiloxane adhesive with antimicrobial properties. This adhesive exhibited enhanced bonding strength through the formation of a substantial number of hydrogen bonds. The carboxyl group in NACL underwent an acid-base neutralization reaction with sodium ethoxide, resulting in the formation of ionic aggregates. These aggregates, along with hydrogen bonding, enhanced the mechanical properties of polysiloxane, leading to a further improvement in bond strength. At ambient temperature, the modified polysiloxane adhesive displayed remarkable lap shear and peel strengths, with maximum values of 8.16 MPa and 20.48 N/m for metallic iron, 3.56 MPa and 14.99 N/m for metallic aluminum, and 5.55 MPa and 20.52 N/m for metallic copper. Furthermore, the inclusion of NACL in the polysiloxane adhesive demonstrated pronounced inhibition against Staphylococcus aureus. As such, this high-performance polysiloxane adhesive has significant potential for use in the metallic bonding of medical devices, adhesive coating of metallic surfaces, and skin adhesion coating.