Integrating transient and sacrificial bonds into biobased elastomers toward mechanical property enhancement and macroscopically responsive property

The development of biobased polymers from renewable resources offers a solution to the growing environmental concerns and scarcity of fossil feedstock. The synthesized biobased polymers, especially for biobased elastomers, are mechanically weak, which greatly restricts their applications. In the present work, we demonstrate that the integration of transient and sacrificial quadruple H-bonding motifs into as-synthesized biobased elastomer can enhance the mechanical properties and bestow it with adaptive performance. Specially, the biobased elastomer was synthesized through melting poly-condensation using biobased di-acids and diols as the starting materials. The biobased elastomer is covalently crosslinked and grafted with ureido-pyrimidinone (UPy) containing acrylate through thiol-ene click reaction by using pentaerythritol tetra(3-mercaptopropionate) as the linkers. Under external load, UPy aggregations based on H-bonding can function as sacrificial units through reversible rupture and re-formation events, leading to significant improvements on the modulus and strength of the biobased elastomer while maintaining the extensibility. In addition, the dissociation and re-formation of H-bonding under thermal stimuli impart the elastomer with thermo-activated shape memory behavior.