writer：Gang Wang, Xinrong Huang, Zhengxiang Zhou, Yi Zhang, Yingfeng Yu *
keywords：(De)bonding on-demand，Optically switchable，Pressure-sensitive adhesives，Coumarin，Photodimerization
source：期刊
specific source：Chemical Engineering Journal 2024, 499，155820
Issue time：2024年

Due to the limited adaptability of conventional adhesives that exhibit either permanently strong or reversibly weak adhesion, growing attention has been paid to switchable or programmable adhesives whose adhesion strength could be regulated on demand. Herein, we present a versatile photo-switchable pressure sensitive adhesives (S-PSA) tape platform featuring in coumarin/acrylate co-capped polyurethane prepolymers (CouPUA). Two S-PSA tapes are prepared for bonding on-demand (PSA-4) and debonding on-demand (PSA-3′) by copolymerization with acrylate monomers and CouPUA prepolymers. For bonding on-demand, the switch-on peel strength of PSA-4 is up to 10.15 N cm?1 with impressive storage stability under ambient light. Meanwhile, the peel strength could be decreased via irradiating light at 365 nm, which triggers the photodimerization of dangled coumarin moiety and therefore increases the crosslinking degree of PSA. The switch-off peel strength is low to 0.73 N cm?1. It can recover to 6.63 N cm?1 by irradiating under light at 254 nm, which activates the photocleavage of dimerized coumarin moiety. Notably, well-defined spatiotemporal control of peel strength is achieved by a synergistic strategy combining photodimerization with mask geometric design. Intriguingly, PSA-4 exhibits unexpectedly enhanced peel strength under the debonding on-demand procedure. In addition, for debonding on-demand, photodimerization-induced overcuring could still be achieved after 72 h of attachment for PSA-3′ accompanying the peel strength decreases from 4.73 to 0.97 N cm?1. These results remarkably broaden the performance scope of S-PSA and have a direct influence on the fields that require on-demand adhesion.

全文链接：https://authors.elsevier.com/a/1jsQn_VWlWHRyF   (before November 20, 2024)