High-performance mussel-inspired adhesives of reduced complexity

TLDR

Underwater adhesion remains limited despite recent advances, largely because mussel‑inspired wet adhesives rely on complex catechol‑functionalized polymers and multi‑step processing that require extensive optimization. The study aims to simplify wet adhesive primers by developing low‑molecular‑weight catecholic zwitterionic surfactants that exhibit strong adhesion and retain coacervation ability. The catecholic zwitterion adheres to diverse surfaces and self‑assembles into a smooth, sub‑4‑nm, strong glue layer. The resulting surfactant achieves ~50 mJ m⁻² adhesion, forms a thin (<4 nm) glue layer, and shows promise for nanofabrication, demonstrating that combining catechol with hydrophobic and electrostatic groups in a small molecule can simplify wet‑adhesion design.

Abstract

Despite the recent progress in and demand for wet adhesives, practical underwater adhesion remains limited or non-existent for diverse applications. Translation of mussel-inspired wet adhesion typically entails catechol functionalization of polymers and/or polyelectrolytes, and solution processing of many complex components and steps that require optimization and stabilization. Here we reduced the complexity of a wet adhesive primer to synthetic low-molecular-weight catecholic zwitterionic surfactants that show very strong adhesion (∼50 mJ m(-2)) and retain the ability to coacervate. This catecholic zwitterion adheres to diverse surfaces and self-assembles into a molecularly smooth, thin (<4 nm) and strong glue layer. The catecholic zwitterion holds particular promise as an adhesive for nanofabrication. This study significantly simplifies bio-inspired themes for wet adhesion by combining catechol with hydrophobic and electrostatic functional groups in a small molecule.