Dual Cross-linked Vinyl Vitrimer with Efficient Self-Catalysis Achieving Triple-Shape-Memory Properties

Abstract

As an emerging class of dynamic cross-linked network, vitrimers have attracted much attention due to the combination of mechanical advantages of thermosets and recyclability of thermoplastics at an elevated temperature. In particular, most vitrimers with multi-shape memory properties usually involve more than one thermal transition or molecular switch, which might pose a challenge for facile sample fabrication and potentially limits their applications. In pursuit of a more universal and simple route, utilizing commercially available and inexpensive reagents to prepare shape-memory vitrimers with dual cross-linked network from vinyl monomer-derived prepolymers is reported here. Copolymerization of desired vinyl monomers gives prepolymers containing carboxyl and zinc carboxylate groups, which are later converted into vitrimers in a single step by post-curing with diglycidylether of bisphenol A. The Zn²⁺ ions can not only act as physical crosslinking points through ionic coordination interactions, thus providing the triple-shape-memory properties, but also play the role of catalyst to activate transesterification in the dynamic covalent network. This new self-catalyzed vitrimer has excellent transesterification efficiency, triple-shape-memory properties, and can be sufficiently healed and reprocessed at an elevated temperature. The proposed molecular design of self-catalyzed materials opens a new avenue toward commercially relevant fabrication of high-performance vitrimers with multiple shape-memory properties.

Keywords: dual cross-linked; ionic cross-linking; self-catalysis; triple-shape memory; vinyl vitrimers.