Difference between Mechanochromism and Photochromism of Aminobenzopyranoxanthene in Single-Network and Double-Network Elastomers

We here report different mechanochromic and photochromic behaviors of double-spiro mechanophore ABPX-2OH in single-network polyurethane (PU) elastomer and double-network polymethacrylate-polyurethane (PMA–PU) elastomer. Distinct from in solution, ABPX undergoes a photoinduced single-ring-opening reaction but suffers a force-induced simultaneous ring-opening reaction of double spirocycles in bulk elastomers. Furthermore, the prestretching effect in PMA–PU promotes the mechanochromism of ABPX-2OH significantly, while reducing the free volume to impede the photochromism of ABPX-2OH sharply. The double-spiro mechanophore combined with the interpenetrating polymer network strategy exhibits a controllable multistate stimuli-responsive platform to realize multicolor switches by different stimuli, which not only can improve the recognition ability for stimuli in complex environments but also shows potential in programmable sensing and display.