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Issue 1, 2014
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Multifunctional poly(ester urethane) laminates with encoded information

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Solvent-cast films from shape memory poly(ester urethane) (PEU) containing different weight contents of microencapsulated thermochromic pigments (T-PIGs) were prepared by drying in air. Spectrophotometric investigations unveiled that gradual loading with T-PIG black resulted in continuous darkening of the films up to filler contents of 20 wt%, accompanied by a steady enhancement of thermochromic properties. Taking this composition as standard, PEU films equipped with T-PIG black, blue and red were deposited atop PEU plaques to obtain laminate structures. Herein, the cover layer thickness (100 ± 5 μm) and the good dispersion of T-PIGs inside the polymer matrix were verified by scanning electron microscopy. Machine-readable information carriers were prepared by laser engraving quick response (QR) codes into the cover layer of the laminates and subsequently cutting cuboidal samples therefrom. Finally, thermo-mechanical programming of the QR code carriers was applied to randomly distort the code patterns, thus rendering them unreadable. Upon heating, surface decolorization and shape recovering occurred; during the ensuing cooling, the surface color and contrast reappeared whereupon the QR codes could be read out. Spectrophotometric, calorimetric and thermo-mechanical investigations gave evidence that the color switching temperature of the T-PIGs roughly coincided with the melting temperature of the ester-based switching segment and thus with the activation temperature of the shape memory effect. Apart from that unique functionality, manifold design concepts may render information carriers difficult-to-copy. Therefore, we anticipate tremendous potential as anti-counterfeiting technology.

Graphical abstract: Multifunctional poly(ester urethane) laminates with encoded information

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Publication details

The article was received on 08 Oct 2013, accepted on 06 Nov 2013 and first published on 20 Nov 2013

Article type: Paper
DOI: 10.1039/C3RA45651J
RSC Adv., 2014,4, 286-292

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    Multifunctional poly(ester urethane) laminates with encoded information

    M. Ecker and T. Pretsch, RSC Adv., 2014, 4, 286
    DOI: 10.1039/C3RA45651J

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