In 2021, China's adhesive production reached 7.09 million tons, while the corresponding waste would turn into another man-made disaster. A paradigm shift toward a more sustainable future can be made through fully recyclable adhesives with a circular life. However, the existing recyclable adhesives suffer from low adhesion strength and poor durability in complex application conditions. In addition, flame retardancy is a key requirement for adhesives in many specific applications. For example, adhesives for electronic device applications often require high flame retardancy to reduce potential fire risks. The development of high-performance reversible adhesives with closed-loop recyclability and multifunction remains a huge challenge in adhesion science and materials engineering.
Recently, Prof. Xiu-Li Wang, Prof. Hai-Bo Zhao and co-workers report a fully recyclable multifunctional adhesive with outstanding advantages of circular life, strong adhesion strength, excellent durability, various harsh-condition resistances, transparency, and flame retardancy. The designed aromatic siloxane adhesive exploits stimuli-responsive reversible assembly driven by π-π stacking, allowing for elimination and activation of interfacial interactions via permeation-volatilization of ethanol. The adhesive can be assembled into an ordered layered micromorphology during ethanol volatilization, resulting in high transmittance (~98%), low haze (~2.5%), as well as robust cohesive energy. Consequently, the water-insensitive siloxane adhesive exhibits strong and durable adhesion (up to 3.5 MPa) on diverse materials. Long-term strong adhesion performances are realized even in harsh conditions of high humidity (85% RH), underwater, salt and strong acid/alkali solutions (pH 1-14), and low/high temperatures (-10-90 ℃). Notably, with reversible assembly/disassembly, the adhesive can be fully closed-loop recycled (~100%) and reused over 100 times without loss of adhesion. In addition, combined with high flame retardancy, the adhesive can be directly used as a durable protective coating, which exhibits unique advantages in many specific applications.
This work is published in Science Advances entitled “Fully recyclable multifunctional adhesive with high durability, transparency, flame retardancy, and harsh-environment resistance”. Prof. Xiu-Li Wang and Prof. Hai-Bo Zhao are the corresponding authors, Zi-Hao Wang is the first author. This work was supported by the National Natural Science Foundation of China, Young Elite Scientists Sponsorship Program by CAST, the 111 Project (B20001), Fundamental Research Funds for the Central Universities, and Institutional Research Fund form Sichuan University (2021SCUNL201).
Link: https://www.science.org/doi/10.1126/sciadv.add8527
