Mechanically Robust and Recyclable Vanillin-Based Polyurethane Elastomers toward Sustainable Adhesives with High Adhesion Strength and Ultralow-Temperature Resistance

Polyurethane (PU) elastomers fabricated using renewable resources are currently being actively explored and pursued to address the resource crisis. The development of biobased PU elastomers with excellent mechanical strength and recyclability remains a scientific challenge. Herein, a series of vanillin-based PU elastomers (PUUA x ) with excellent mechanical strength and recyclability are fabricated through the condensation polymerization of poly(propylene glycol) tolylene-2,4-diisocyanate (PPGTD) and sebacoyl hydrazide (SDH) followed by the chain extension of biobased divanillin (DVA). In this design, numerous hydrogen bonds will be generated from the urea and acylhydrazone bonds derived from the reaction of SDH with PPGTD and DVA in the polymer networks of PU elastomers. The as-fabricated vanillin-based PU elastomers exhibit an excellent mechanical strength of ∼56.7 MPa, an ideal tensile strain of ∼1209%, a high toughness of 249.6 MJ m –3, excellent puncture resistance, and excellent elastic recovery ability at room temperature. In addition, due to the presence of various polar groups in the chemical structure of PUUA x, these vanillin-based PU elastomers can be used as high-performance adhesives. PUUA x adhesives show an excellent bonding strength to a variety of substrates. In particular, the lap-shear strength on stainless steel substrates can be as high as ∼15.5 MPa. Moreover, PUUA x adhesives also exhibit excellent tolerance under ultralow-temperature conditions (−196 °C). After being placed at −196 °C for 30 days, the lap-shear strength of the bonded stainless steel substrates still remained at ∼15.3 MPa. This work provides a strategy for developing mechanically strong and recyclable biobased PU elastomers with the potential for use as high-performance and sustainable adhesives that can be used in ultralow-temperature environments.