Synthesis And Fluorescence Behavior Of A Thermoresponsive Polymer Ended With Fluorescent Group

In this paper, we report the synthesis of a thermoresponsive polymer ended with fluorescent group. And the temperature dependence of its fluorescence intensity was further investigated.On one hand, through a series of simple organic reactions (including the Knoevenagel reaction, Sonogashira reaction, Diels-Alder reaction etc.) we prepared two novel fluorescent compunds 4 and 6. In order to confirm the structures, we did the characterization of NMR (involved'H NMR, 13C NMR, two-dimensional NMR), FTIR and MS(ESI). The crystal structures of compound 4 and 6 were also obtained to further verify the structures. Then compunds 4 and 6 were examined by UV, FL and Luminescence, respectively, which confirmed that compund 6 had a greater conjugated structure than 4.On the other hand, PNIPAm with medium molecular weight and very narrow molecular weight distribution was gained by the method of RAFT of living/controlled radical polymerization. The prepared polymer was characterized by 1H NMR, IR and gel permeation chromatography (GPC) to confirm its structure and molecular weight. Subsequently, PNIPAm-MAh was synthesized by MAh as a functional molecule reacted with the as-prepared polymer.Finally, P-M-6, the thermoresponsive polymer ended with fluorescent group was successfully synthesized by acylation reaction of fluorescent molecule 6 and PNIPAm-MAh prepared beforehand. Meanwhile, the temperature dependence of LCST and the fluorescence intensity of P-M-6 were studied. The thermoresponsive polymer may have potential applications in drug delivery systems as a thermoresponsive switch.