High-performance mussel-inspired adhesives of reduced complexity

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.

Linear viscoelasticity of complex coacervates

“…The self-assembly of these materials is driven by entropy, where the initial electrostatic attraction between oppositely-charged macro-ions results in the release of small, bound counter-ions and the restructuring of water molecules [1][2][3][4]. Complex coacervates have a long history of use in the food [5][6][7][8][9][10][11][12][13] and personal care [14,15] industries, and have found increasing utility as a platform for drug and gene delivery [1][2][3][4], as well as underwater adhesives [5][6][7][8][9][10][11][12][13][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62]. Coacervation has also recently been implicated in the formation of various biological assemblies [1,[14][15][16]55,…”

Hydrophobicity‐enhanced adhesion of novel biomimetic biocompatible polyaspartamide derivative glues

“…PolyAspAm(DOPA/LA) > PolyAspAm(DOPA/OA) > PolyAspAm(DOPA/HA) > PolyAspAm(DOPA/BA). In other words, as the alkyl chain length increases, the adhesive strength increases accordingly . In the case of copper, a relatively low level of adhesive strength was observed with values of 0.03–0.09 MPa, probably due to the extraordinarily smooth surface of copper substrates .…”

Functional Polymeric Materials Inspired by Geckos, Mussels, and Spider Silk

“…The literature contains a variety of synthetic adaptations, with emphasis on the reduced complexity and improved tractability of the structure and adhesive mechanism. Examples include a random copolymer in which positively and negatively charged acrylates are incorporated, a hydrophobic aryl moiety, a catechol, or a neutral hydrophobic group; but also a small molecule that incorporates the aforementioned characters, and, finally, synthetic peptide mimics of the P. californica , sandcastle worm, adhesives …”