Macromolecular Metabolism Based on Enaminoneamide Achieving Transformation of Polymer Architecture

Cross-linked polymers are indispensable, but their intractability also puts a great and heavy burden on the environment after the end of use. Although some novel reversible chemistries endue them with reprocessing abilities, their practical potentials are limited by the deteriorated performance after the reprocessing cycle. In this paper, the reaction of enaminone with isocyanate to form enaminoneamide is used to create a new dynamically cross-linked polyurethane with two essential properties. One is that the gel–sol–gel process allows the cross-linked PU to repolymerize itself. The other is that, based on the preferred interaction between amine and isocyanate from the dissociation of enaminoneamide, amine chemicals can be employed as scissors to cut the cross-linked PU, and our unique cross-linked PU can be changed from a cross-linked network to a linear structure. Without the further purification, this type of de-cross-linked polymer can be utilized as a raw material to make new types of re-cross-linked PU, referred to as "children" (new generations) of recycled PU. Like protein metabolism, the designed cross-linked PU exhibits two perfect (closed and open) recycling cycles. This type of metabolism-like reprocessing capability provides great freedom to produce recyclable polymers with high value and customizable features.