Synthesis and characterization of Rosebengal end-capped poly(o-chloroaniline)/Ag nanocomposite-based NIR fluorescent probe: a structure-property relationship study

Nowadays, an economically cheaper, NIR fluorescent probe is needed in order to identify the cancerous cells without skin cells damage. For this purpose, conventional conducting polymers are used. Under N₂ environment, the chemical polymerization of o-chloroaniline (OCA) was initiated by peroxydisulphate (PDS) with the help of rosebengal (RB) dye, both in the presence and absence of a 3% weight loading of Ag⁺ ion. The weight of the polymer was used to calculate the rate of polymerization (Rp) and yield percentage. Additionally, FTIR, UV–visible, fluorescence emission, thermogravimetric analysis, scanning electron microscopy and differential scanning calorimetry were used to analyse the poly(o-chloroaniline) (POCA) structure–property relationship. The FTIR spectrum confirmed the presence of benzenoid and quinonoid structures in POCA chains. The percentage yield and Rp both marginally increased in the presence of Ag⁺ ions. The Tg of RB end-capped POCA/Ag nanocomposite system was determined as 103°C. The energy of activation (Ea) value of 66.17 kJ mol^-1 was found for the structural degradation of RB in RB end-capped POCA. In comparison to the straightforward RB end-capped POCA system, the POCA/Ag o nanocomposite system has higher thermodynamic parameter values. The experimental findings are thoroughly examined and contrasted with the values given in the literature. (author)