One-component intrinsic self-healing polymer for coatings based on reversible crosslinking by Diels-Alder-cycloadditions

Abstract

Self-healing can be achieved in polymer coatings by the incorporation of extrinsic materials, i.e. a healing agent is embedded into the coating (e.g., within capsules). In contrast the polymeric coating itself can feature the ability for healing – for instance if reversible covalent bonds are introduced into the polymer network. The Diels-.Alder reaction is one prominent example to obtain reversibility within self-healing/mendable materials. In this context, a novel acrylic-based one-component polymer system has been synthesized, which contains both binding units for the Diels-Alder reaction (i.e. the maleimide and the furan moiety) as well as comonomers to tune the mechanical as well as thermal properties. The ATRP (atom transfer radical polymerization) of maleimide methacrylate (MIMA), furfuryl methacrylate (FMA) as well as of different alkylmethacrylates was utilized to synthesize well-defined functional terpolymers, which could be crosslinked subsequently via thermal treatment. The mechanical and thermal properties of these polymers have been investigated in detail. Moreover, the healing ability of these polymer coatings was studied. The influence of the crosslinking density, the kind of the comonomer and the healing temperature was investigated in detail. An efficient healing of these coatings could be observed. Additionally first attempts to tune the healing temperature of these coatings have been performed. The comonomers can also influence the required temperature for the retro-Diels-Alder reaction.