Exploiting Supramolecular Interactions from Polymeric Colloids for Strong Anisotropic Adhesion between Solid Surfaces

Blaise L Tardy; Joseph J Richardson; Luiz G Greca; Junling Guo; Hirotaka Ejima; Orlando J Rojas

doi:10.1002/adma.201906886

Exploiting Supramolecular Interactions from Polymeric Colloids for Strong Anisotropic Adhesion between Solid Surfaces

Adv Mater. 2020 Apr;32(14):e1906886. doi: 10.1002/adma.201906886. Epub 2020 Feb 16.

Authors

Blaise L Tardy¹, Joseph J Richardson², Luiz G Greca¹, Junling Guo^{3

4}, Hirotaka Ejima², Orlando J Rojas^{1

5

6}

Affiliations

¹ Department of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, Espoo, 02150, Finland.
² Department of Materials Engineering, The University of Tokyo, Tokyo, 113-8656, Japan.
³ School of Biomass Science and Engineering, Sichuan University, Chengdu, 610017, China.
⁴ Wyss Institute for Biologically Inspired Engineering, John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, USA.
⁵ Department of Applied Physics, School of Science, Aalto University, Espoo, 02150, Finland.
⁶ Departments of Chemical and Biological Engineering, Chemistry and Wood Science, University of British Columbia, 2360 East Mall, Vancouver, BC, V6T 1Z4, Canada.

PMID: 32064702
DOI: 10.1002/adma.201906886

Abstract

Adhesion occurs by covalent bonding, as in reactive structural adhesives, or through noncovalent interactions, which are nearly ubiquitous in nature. A classic example of the latter is gecko feet, where hierarchical features enhance friction across the contact area. Biomimicry of such structured adhesion is regularly achieved by top-down lithography, which allows for direction-dependent detachment. However, bottom-up approaches remain elusive given the scarcity of building blocks that yield strong, cohesive, self-assembly across multiple length scales. Herein, an exception is introduced, namely, aqueous dispersions of cellulose nanocrystals (CNCs) that form superstructured, adherent layers between solid surfaces upon confined evaporation-induced self-assembly (C-EISA). The inherently strong CNCs (E_A > 140 GPa) align into rigid, nematically ordered lamellae across multiple length scales as a result of the stresses associated with confined evaporation. This long-range order produces remarkable anisotropic adhesive strength when comparing in-plane (≈7 MPa) and out-of-plane (≤0.08 MPa) directions. These adhesive attributes, resulting from self-assembly, substantially outperform previous biomimetic adhesives obtained by top-down microfabrication (dry adhesives, friction driven), and represent a unique fluid (aqueous)-based system with significant anisotropy of adhesion. By using C-EISA, new emergent properties will be closely tied with the nature of colloids and their hierarchical assemblies.

Keywords: adhesion; cellulose; colloids; self-assembly; supramolecular interactions.

Abstract

Grants and funding