Transparent Ultraviolet-Shielding Poly(ester amide) Elastomers with Excellent Elastic Recovery via Hydrogen-Bonding Compensation

Abstract

Abstract Developing sustainable elastomers that synergistically integrate intrinsic ultraviolet (UV) shielding, high elasticity, and optical transparency remains a fundamental challenge, as rigid chromophores essential for UV absorption inherently compromise network dynamics and resilience. To address this conflict, we propose a molecular design strategy based on programmable hydrogen-bonding interactions. Employing a single bioderived bifunctional unit, which integrates both amide groups for hydrogen bonding and a vanillin-derived conjugated system for UV absorption, we synthesize a series of triblock poly(ester amide) elastomers via Knoevenagel polycondensation. We demonstrate that the strategically tuned, reversible hydrogen-bonding network effectively compensates for the stiffening effect induced by the conjugated units. Quantitative Fourier transform infrared spectroscopy analysis reveals an optimal effective hydrogen-bonding content (39.47%) for the PHNB60% sample, which also exhibits a well-defined nanoscale microphase-separated structure as visualized by atomic force microscopy. This optimized elastomer consequently reconciles UV-shielding capability with elastic recovery, achieving an exceptional combination of properties: high extensibility, outstanding elastic recovery (approaching 99%), broad-spectrum UV shielding (200–430 nm), and good resistance to UV aging, all while retaining visible-light transparency. This work establishes “hydrogen-bond-compensated functionalization” as a molecular design principle, enabling intrinsic UV shielding, excellent elastic recovery, and mechanical robustness to be achieved synergistically.