Mechanically Ultra-Strong Pectin with Enhanced Electro-Optic Properties for Bioelectronics via Low-Temperature Supercritical Self-Cross-Linking

Pectin, a widely available biomaterial, has become a promising candidate for bioelectronics. However, residual free carboxyl groups from the extraction process (commonly acid solubilization) cause poor optoelectronic stability, low transparency, and high electrical leakage, rendering pectin unsuitable for bioelectronics. This study employs a biomaterial-friendly supercritical carbon dioxide self-cross-linking (SCS) method to achieve the self-cross-linking of pectin molecules without a cross-linking agent or catalyst at low temperatures, resulting in enhanced pectin properties. SCS treatment induces esterification of free carboxyl groups with the pectin main chain, forming cross-linked ether bonds via intermolecular dehydration, leading to a denser structure replacing the original loose porous structure. The treated pectin film demonstrates superior optoelectronic performance, with a 4-fold reduction in leakage current and enhanced yellow-green light transmittance. An ultra-strong pectin material is obtained, whose Young’s modulus increased to 1.31 GPa, a 21.9% improvement over the untreated material, outperforming other pectin sources. The low-temperature supercritical method enhances pectin’s optoelectronic properties, making it more suitable for bioelectronics, while achieving unprecedented material strength through self-cross-linking. This advancement minimizes functional layer deformation, reduces power consumption, and extends the bioelectronics lifespan.