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.