Rational design of thermally reprocessable microphase-separated ionomer with creep resistance and recoverability

Designing reprocessable polymeric materials while maintaining long-term dimensional stability has been recognized as a critical challenge in sustainable materials development. Ion-containing polymers, especially the ones with low charge densities, i.e., ionomers, demonstrate improved toughness due to physical crosslinks of ionic clusters. However, at elevated temperatures, ionic associations become more transient, leading to softening and even terminal flow. In this talk, we will demonstrate that when ionic monomers are confined into a block, diblock ionomers retain elasticity over a wide temperature range, resist creep, and exhibit greater than 90% recovery after five creep-recovery cycles.

Unlike statistical ionomers with 1-3 nm ionic cluster formation, diblock ionomers self-assemble into a highly ordered inverse hexagonal (iHEX) structure with large interdomain spacing (> 30 nm). The glassy ionic domain acts as a rigid scaffold, significantly slowing interdomain diffusion, while the soft, rubbery neutral domain provides flexibility within the cylinders and enables reprocessability. The diblock ionomer is compression moldable at 80 °C while maintaining good mechanical integrity. By tuning the ion distribution, we convert a thermoplastic-like ionomer into a reprocessable elastomer, outperforming conventional thermoplastic elastomers and providing design guidelines for dynamic polymers with mechanical robustness, recoverability, and sustainability.