Synthesis and preparation of p-terphenyl based polymer with stable fluorescence performance

Based on the rigid structure and conjugation effect of terphenyl, a series of p-terphenyl copolymers (TP-x) were synthesized in this study to investigate the effect of p-terphenyl group on the thermal, optical, and processability of the materials. It was found that Td of the polymers increased from 390 °C (10% p-triphenyl content) to 407 °C (30% p-triphenyl content) in O2. In addition, the fluorescence intensity of the polymer in liquid state enhanced with the enhancement of p-terphenyl content. However, in the solid state, the fluorescence intensity of the samples actually decreased with the increase of p-terphenyl. This is related to the aggregation state of molecular chains. In order to avoid the fluorescence quenching phenomenon caused by the stacking of molecular chains, the polymers were produced into the nanofiber membranes. The electrospun fibers exhibited the bright blue. The fluorescence stability of the fiber membranes were further studied via immersing the fiber sample in different pH solutions. The results showed that the membranes exhibited relatively stable luminescence under acidic conditions, and the fluorescence retention rate under alkaline conditions could reach to 86.5%. This indicates that the polymer membranes developed in this work can be the competitive candidate for flexible fluorescent labeling.