The pH sensitive fluorescence SiO2@TEuTTA/CS composite films and inks for anti-counterfeiting

Functional chitosan (CS) composite films have wide application prospects in many fields. Herein, the lanthanide inorganic-organic hybrid nanospheres with an average diameter of 252 nm (SiO2@TEuTTA) were synthesized by surface modification of silica nanospheres. And the SiO2@TEuTTA was used as luminescent materials and SiO2@TEuTTA/CS composite films were prepared by a simple solution casting method. Subsequently, the compositions and structure, fluorescence and mechanical properties of the SiO2@TEuTTA/CS composite films were characterized. The results show that the SiO2@TEuTTA/CS composite films not only have the smooth surface, high fluorescence property, good flexibility and transparency, but also can emit a bright red color under a 365 nm UV lamp. These provide an important basis for the application of the SiO2@TEuTTA/CS composite films on the anti-counterfeiting packing labels. Additionally, the SiO2@TEuTTA/CS solutions have been successfully used as anti-counterfeiting inks due to its transparency and pH sensitive properties. Compared with the traditional luminescent anti-counterfeiting inks, the pH sensitive SiO2@TEuTTA/CS inks can improve the level of information security, which indicates that the SiO2@TEuTTA/CS inks hold great promise for anti-counterfeiting fields.