High-performance, command-degradable, antibacterial Schiff base epoxy thermosets: synthesis and properties

Abstract

Two diepoxides containing a two-benzene-ring-conjugated Schiff base when cured with an aromatic diamine result in high-performance thermosets combining excellent controlled degradability, stability and antibacterial properties. Epoxy resins have been widely used in coatings, adhesives, composites, electronic packaging materials, etc., but they are arduous to recycle and have no antibacterial activity. In this paper, two-benzene-ring-conjugated Schiff base diepoxy monomers were synthesized and further cross-linked with 4,4-diaminodiphenylmethane. The chemical structures of the diepoxides as well as their thermosets were characterized in detail. The property investigation manifested that the thermosets possessed a far higher glass transition temperature of ∼206 °C, tensile strength of ∼122 MPa, and tensile modulus of ∼2646 MPa than a commonly used high-performance bisphenol A epoxy resin. Moreover, they possessed excellent acidity and temperature-controlled degradability, and superior stability in common solvents, thermal treatment and hygrothermal aging. Furthermore, they presented excellent coating properties (including hardness, adhesion, and solvent resistance) and antibacterial properties with a bactericidal capability of ∼91%.