3D Printing of Elastomeric Bioinspired Complex Adhesive Microstructures

Abstract

Bioinspired elastomeric structural adhesives can provide reversible and controllable adhesion on dry/wet and synthetic/biological surfaces for a broad range of commercial applications. Shape complexity and performance of the existing structural adhesives are limited by the used specific fabrication technique, such as molding. To overcome these limitations by proposing complex 3D microstructured adhesive designs, a 3D elastomeric microstructure fabrication approach is implemented using two‐photon‐polymerization‐based 3D printing. A custom aliphatic urethane‐acrylate‐based elastomer is used as the 3D printing material. Two designs are demonstrated with two combined biological inspirations to show the advanced capabilities enabled by the proposed fabrication approach and custom elastomer. The first design focuses on springtail‐ and gecko‐inspired hybrid microfiber adhesive, which has the multifunctionalities of side‐surface liquid super‐repellency, top‐surface liquid super‐repellency, and strong reversible adhesion features in a single fiber array. The second design primarily centers on octopus‐ and gecko‐inspired hybrid adhesive, which exhibits the benefits of both octopus‐ and gecko‐inspired microstructured adhesives for strong reversible adhesion on both wet and dry surfaces, such as skin. This fabrication approach could be used to produce many other 3D complex elastomeric structural adhesives for future real‐world applications.

Robust and durable liquid-repellent surfaces

“…188 These specific doubly and even triply re-entrant structures show incomparable advantages in creating the structural basis for superoleophobicity, and have been widely employed in the design of excellent super oil-repellent surfaces. 191,192,[224][225][226][227] However, these well-defined re-entrant microstructures are usually fabricated by reactive ion etching, 188 photopolymerization based 3D printing, 191,192,[224][225][226][227][228][229] or recently-reported laser-induced localised heating and ablation of a bilayer matrix, 216 which suffer from limited substrate selection and difficulty for scale-up production. Recently, by harnessing the configurable elastic crack engineering, Li et al proposed a facile and high-efficient method to construct arbitrary hierarchical structures (including well-defined, regular array structures) with broad material compatibility by harnessing the configurable elastic crack engineering, and as an example, they fabricated a superoleophobic polypropylene surface with an array of doubly re-entrant structures (Fig.…”

Bio-macromolecular design roadmap towards tough bioadhesives

“…Recently, high-resolution 3D printing using two-photon polymerization was used to fabricate flexible springtail-gecko-inspired adhesive patches from acrylated urethanes. 330 The patches consisted of pillar microstructures that repel liquids from the sides to establish wet adhesion. It was further demonstrated that modifying the pillars by adding octopus-inspired suction cups on the micropillars can significantly improve adhesion compared to those of patches with simple pillar architectures.…”

One-step laser etching of a bionic hierarchical structure on a silicone rubber surface with thermal and acid/alkali resistance and tunable wettability

“…Many methods have been used to construct surface micro/nano structures on silicone rubber surfaces, such as laser etching, 31 spray coating, 32 3D printing, 33 compression molding, 34 injection molding, 35 and soft lithography. 36 Among the above methods, laser etching is an industrial technology and is suitable for preparing rich micro/nanostructures on the surfaces of semiconductors, brittle materials, metals, polymers, ceramics and biomaterials.…”