The surface of a shape memory poly(ester urethane) (PEU) was either black- or blue-colored to obtain switchable quick response (QR) codes after laser engraving and thermo-mechanical functionalization (programming). The investigation of dye and functional stability against UVA and hydrolytic aging (at 23 and 60 °C) gave that contrast decline due to dye decolorization (in case of UVA aging) or distinct dye diffusion (in case of hydrolytic aging) finally inhibited the QR code readability. By contrast, PEU as marked base material could be adequately fixed and recovered even when the Michelson contrast in the QR code region was falling in course of aging below a crucial value of 0.1, whereupon the QR code was no longer readable. Hence, we concluded that under the given experimental conditions the decisive parameter for tag applicability was the surface contrast.

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