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Underwater contact adhesion and microarchitecture in polyelectrolyte complexes actuated by solvent exchange


Polyelectrolyte complexation is critical to the formation and properties of many biological and polymeric materials, and is typically initiated by aqueous mixing1 followed by fluid–fluid phase separation, such as coacervation2,3,4,5. Yet little to nothing is known about how coacervates evolve into intricate solid microarchitectures. Inspired by the chemical features of the cement proteins of the sandcastle worm, here we report a versatile and strong wet-contact microporous adhesive resulting from polyelectrolyte complexation triggered by solvent exchange. After premixing a catechol-functionalized weak polyanion with a polycation in dimethyl sulphoxide (DMSO), the solution was applied underwater to various substrates whereupon electrostatic complexation, phase inversion, and rapid setting were simultaneously actuated by water–DMSO solvent exchange. Spatial and temporal coordination of complexation, inversion and setting fostered rapid (25 s) and robust underwater contact adhesion (Wad ≥ 2 J m−2) of complexed catecholic polyelectrolytes to all tested surfaces including plastics, glasses, metals and biological materials.

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Figure 1: Materials inspiration and underwater adhesion.
Figure 2: Mechanism and materials characterization.
Figure 3: Effect of setting time in water on solvent exchange and adhesion.
Figure 4: Underwater friction experiments of mica versus adhesive-coated glass performed using an SFA.


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The authors gratefully acknowledge financial support from the National Science Foundation (NSF) through the MRSEC Program DMR-1121053 (MRL-UCSB), which also supported the MRL Central Facilities (a member of the NSF-funded Materials Research Facilities Network ( J.H.W. and B.K.A. acknowledge support from the Office of Naval Research N000141310867. J.H.W. and J.N.I. also acknowledge support from the US National Institutes of Health (R01 DE018468). Authors thank R. Mirshafian for help with optical microscope and W. Wei for discussions.

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Authors and Affiliations



Q.Z. and J.H.W. conceived the concept of materials processing. Q.Z. was responsible for the experimental part with input from B.K.A. who advised on PAAcat synthesis, SFA, confocal microscopy and FTIR. S.S. synthesized PAAcat copolymers. D.W.L. planned and performed SFA experiments and analysed the data. D.W.L. and B.K.A. performed and analysed confocal microscope experiments. Q.Z., D.W.L., B.K.A. and J.H.W. analysed data and wrote the paper. All authors read and commented on the paper. J.H.W. supervised the overall project.

Corresponding authors

Correspondence to Jacob N. Israelachvili or J. Herbert Waite.

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The authors declare no competing financial interests.

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Zhao, Q., Lee, D., Ahn, B. et al. Underwater contact adhesion and microarchitecture in polyelectrolyte complexes actuated by solvent exchange. Nature Mater 15, 407–412 (2016).

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