Fibrillar adhesives with unprecedented adhesion strength, switchability and scalability

Changhong Linghu; Yangchengyi Liu; Xudong Yang; Dong Li; Yee Yuan Tan; Mohamed Haziq Bin Mohamed Hafiz; Mohammad Fadhli Bin Rohani; Zihao Du; Jiangtao Su; Yan Li; Yucheng Huo; Hanyan Xu; Xiufeng Wang; Yifan Wang; Jing Yu; Huajian Gao; K Jimmy Hsia

doi:10.1093/nsr/nwae106

Fibrillar adhesives with unprecedented adhesion strength, switchability and scalability

Natl Sci Rev. 2024 Mar 20;11(10):nwae106. doi: 10.1093/nsr/nwae106. eCollection 2024 Oct.

Authors

Changhong Linghu¹, Yangchengyi Liu^{1

2}, Xudong Yang¹, Dong Li¹, Yee Yuan Tan¹, Mohamed Haziq Bin Mohamed Hafiz¹, Mohammad Fadhli Bin Rohani¹, Zihao Du^{1

3}, Jiangtao Su⁴, Yan Li¹, Yucheng Huo¹, Hanyan Xu⁴, Xiufeng Wang², Yifan Wang¹, Jing Yu⁴, Huajian Gao^{1

5

6}, K Jimmy Hsia^{1

7}

Affiliations

¹ School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Singapore.
² School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105, China.
³ Department of Engineering Mechanics, Zhejiang University, Hangzhou 310027, China.
⁴ School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore.
⁵ Institute of High-Performance Computing, A*STAR, Singapore 138632, Singapore.
⁶ Mechano-X Institute, Applied Mechanics Laboratory, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China.
⁷ School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, Singapore 639798, Singapore.

Abstract

Bio-inspired fibrillar adhesives have received worldwide attention but their potentials have been limited by a trade-off between adhesion strength and adhesion switchability, and a size scale effect that restricts the fibrils to micro/nanoscales. Here, we report a class of adhesive fibrils that achieve unprecedented adhesion strength (∼2 MPa), switchability (∼2000), and scalability (up to millimeter-scale at the single fibril level), by leveraging the rubber-to-glass (R2G) transition in shape memory polymers (SMPs). Moreover, R2G SMP fibrillar adhesive arrays exhibit a switchability of >1000 (with the aid of controlled buckling) and an adhesion efficiency of 57.8%, with apparent contact area scalable to 1000 mm², outperforming existing fibrillar adhesives. We further demonstrate that the SMP fibrillar adhesives can be used as soft grippers and reusable superglue devices that are capable of holding and releasing heavy objects >2000 times of their own weight. These findings represent significant advances in smart fibrillar adhesives for numerous applications, especially those involving high-payload scenarios.

Keywords: JKR-DMT transition; R2G fibrillar adhesives; adhesion switchability and scalability; rubber-to-glass (R2G) transition; shape memory polymers.