Enhanced Mechanochemiluminescence from End-Functionalized Polyurethanes with Multiple Hydrogen Bonds

The chemiluminescent mechanophore, 1,2-dioxetane (Ad), is incorporated into the backbone of a polyurethane-based prepolymer, which is further end-capped with dimerizable strong hydrogen bonding units, ureidopyrimidinone and pyrimidinedione (UPy, DHB-2) or hydrogen bonding free unit (EtOH). Mechanical, optomechanical measurements, and small-angle/wide-angle X-ray scattering (SAXS/WAXS) analyses of these end-functionalized polyurethanes have demonstrated that the difference in the strength of hydrogen bonding interactions led to different degrees of chain orientation in the bulk, and consequently, different levels of mechano-activation of Ad with distinguishable mechanochemiluminescence intensity. This study not only offers a straightforward way to enhance the mechanochemiluminescence of Ad containing polymers by tailoring the supramolecular interactions between different macromers but also deepens our understanding of the correlations between chain orientation behavior, magnitudes of hydrogen bonding interactions, and the activation of mechanophores.