Effects of Molecular Designs and Double‐Network Morphologies for Bioadhesive Semiconductors

ABSTRACT For biointerfaced electronics, bioadhesive properties are critical for achieving intimate and stable interfaces that enable high‐fidelity signal transfer. The recent development of bioadhesive semiconductors has opened opportunities to realize advanced electronic and optoelectronic functionalities directly at bio‐tissue surfaces with long‐term stability. Here, we systematically elucidate the molecular and structural design principles that govern bioadhesive semiconductor (BASC) performance by studying the effects of brush bioadhesive polymer (BAP) side‐chain length, double‐network morphology, and film thickness. BAPs with longer ethylene glycol side chains exhibit enhanced tissue adhesion due to increased water absorption and improved exposure of adhesive groups. Incorporating the semiconducting polymer p(g2T‐T) forms a double‐network structure that increases adhesion toughness through enhanced energy dissipation, while maintaining high charge‐carrier mobility (>0.6 cm 2 V − 1 s − 1 ) across all side chain lengths. Increasing BASC thickness to 200 µm boosts tissue adhesion to 45 J/m 2 , approaching state‐of‐the‐art hydrogel adhesives. The films retain robust tissue adhesion in vivo for two weeks. These findings establish molecular‐to‐mesoscale design principles for BASCs, offering a framework to co‐optimize tissue adhesion and electronic functionalities for advanced implantable bioelectronics.