2.2 Anticounterfeiting and data encryption
Taking advantage of the fluorescent nature of the HBPSi, their
derivatives can be used for latent fingerprint imaging and data
encryption. Figure 9A illustrated the blue fluorescence imaging of
latent fingerprints. The high-quality image with secondary minutiae
features suggests the preferential adhesion of the polymer on the
fingerprint ridge. Bai et al. used HBPSi “ink” to draw “XUST” and
“NO” on a filter paper and only letters written in normal ink could be
observed under daylight (Figure 9B). However, the blue colored “XUST”
and “NO” were visualized by UV excitation, exhibiting a UV-triggered
anticounterfeiting ability.[46]
Basing on the stimulus responses, polysiloxanes have great potential for
data encryption. Our group reported an HBPSi with data encryption
ability derived from the Fe3+ quenching
effect.[41] Using the Na2EDTA as
the ink, HBPSi coated security paper was blue luminescent under UV
light without diversity, thus the
information was encrypted. The painting of a “key”,
Fe3+ solution, can reveal the “AIE 20th” with a blue
emission under UV light due to the Na2EDTA protected
luminescence of HBPSi from Fe3+ caused quenching. As
can be seen in Fig. 9D, the HBPSi serves as a convenient tool for data
encryption without changing the paper’s appearance.