Amino-Functionalized Surface Engineering of Elastomers for Robust PEDOT:PSS-Based Stretchable Electronics

Stretchable devices have attracted significant attention due to their mechanical versatility and potential applications in wearable electronics, soft robotics, and biomedical devices. However, their practical implementation is often hindered by challenges in surface engineering, particularly at the interface between stretchable elastomers and conducting polymers like poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). This study introduces a novel strategy to enhance the performance of stretchable devices by engineering the elastomer substrate surface with 2,6-diaminopimelic acid (DAP), an amino-functionalization approach that improves integration with lab-synthesized PEDOT:PSS. DAP, a key diamino dicarboxylic acid component of Gram-negative bacterial cell wall peptidoglycan, is employed to facilitate amino and hydroxyl group activation on the elastomer surface. This process consequently improves the adhesion, mechanical stability, surface energy, and electrical conductivity at the interface between the elastomer and PEDOT:PSS. The electrical properties of the modified films were assessed under various mechanical deformations, demonstrating enhanced conductivity and stability. Chemical analyses using Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) revealed that DAP functions as an interfacial bridge, forming chemical bonds or complexes between the elastomer surface and the functional groups in PEDOT:PSS. Increased adhesivity was confirmed by a lower contact angle and an improved adhesion energy of 134.4 mN/m. In conclusion, DAP-based surface modification is a promising approach for improving the key properties of stretchable devices. These findings support the development of robust electronics, including wearable heaters and alternating current electroluminescent (ACEL) devices, for broader applications in stretchable technologies.