Rapid, On-Command Debonding of Stimuli-Responsive Cross-Linked Adhesives by Continuous, Sequential Quinone Methide Elimination Reactions

Adhesives that selectively debond from a surface by stimuli-induced head-to-tail continuous depolymerization of poly(benzyl ether) macro-cross-linkers within a poly(norbornene) matrix are described. Continuous head-to-tail depolymerization provides faster rates of response than can be achieved using a small-molecule cross-linker, as well as responses to lower stimulus concentrations. Shear-stress values for glass held together by the adhesive reach 0.51±0.10 MPa, whereas signal-induced depolymerization via quinone methide intermediates reduces the shear stress values to 0.05±0.02 MPa. Changing the length of the macro-cross-linkers alters the time required for debonding, and thus enables the programmed sequential release of specific layers in a glass composite material. The depolymerization of <1 mol % of a macro-cross-linker gives rise to an amplified response in stimuli-responsive cross-linked adhesives. This amplified response enables rapid and sensitive debonding in response to specific stimuli, as well as pre-programmed debonding of layers in composite materials. The use of depolymerizable macro-cross-linkers transforms an inexpensive monomer into a highly stimuli-responsive adhesive.