Special interplay of hydrogen bonds and dynamic covalent bonds in sustainable polyurethane vitrimers with excellent recyclability and reprocessability

Abstract

Constructing various reversible bond networks is one of the effective methods to endow polymers with high mechanical properties and recyclability. However, the interplay mechanisms between different reversible bond networks have not been fully understood. In the current work, the polyurethane (PU) vitrimers containing covalent crosslinking network, dynamic imine bond network and hydrogen bond network were prepared. The PU vitrimers exhibit high mechanical properties (tensile strength and modulus), excellent recyclability and reprocessability. The incorporation of the dynamic imine bonds leads to the increase of the number of hydrogen bonds in the PU vitrimers, and improves the degree of microphase separation between soft and hard segments. The presence of this unique interplay between the two different reversible bond networks endows the PU with superior comprehensive properties. These above findings are helpful to guide the design and development of sustainable PU materials with high comprehensive properties.