Aggregation-induced emission active polyamide based on tetraphenylbutadiene and the application in lubricant detection

After aggregation-induced emission (AIE) was proposed by professor Tang in 2001, the research about AIE molecules and their application have been received widespread attention because of their high photoluminescence quantum efficiencies in the aggregation or solid film states. Developing different AIE polymers had always been a research hotspot in this field. Herein, an AIE-active main-chain polymer TPB-PA based on tetraphenylbutadiene (TPB) was prepared by polycondensation of TPB derivatives with two carboxylic acid groups and diamine. The AIE behavior of TPB-PA was measured in the THF/H₂O mixtures. The fluorescence intensity starts to increase gradually when the water fraction (f_w) is 20%, enhances significantly when f_w is higher than 60%, and reaches the maximum and is 6.8 times of the original intensity at f_w = 90%, which indicates their significant AIE characteristics. Furthermore, the fluorescence spectra of TPB-PA and its precursor TPB-COOCH₃ changed obviously when adding different concentration of lubricants to their THF solution, and the different kinds of lubricants have different influence on the photoluminescence properties, which can be used to recognize different kind of lubricants.