Thermally and Base-Triggered "Debond-on-Demand" Chain-Extended Polyurethane Adhesives

A series of novel chain-extended polyurethanes (CEPUs) featuring degradable sulfonyl ethyl urethane chain-extenders that permit degradation under base-triggered conditions to afford "debond-on-demand" elastomeric adhesives are reported. Exposure of the CEPUs to tetra-butylammonium fluoride (TBAF) triggered the degradation of the sulfonyl ethyl urethane chain-extenders. Lap shear adhesion tests of the CEPUs exposed to TBAF revealed reductions in shear strength of up to 65% for both aluminum and glass substrates, from 2.18 to 0.76 MPa and from 1.13 to 0.52 MPa, respectively. The selective depolymerization of these polymers makes them suitable candidates as debondable binders for inkjet inks and coatings, enabling removal of inks and adhesive residues from substrates before they enter the recycling process, to prevent surface contaminants decreasing the quality of the recycled material.