CO_2-responsive Polymeric Fluorescent Sensor with Ultrafast Response

摘要

Response speed is one of the most important evaluation criteria for CO_2 sensors. In this work, we report an ultrafast CO_2 fluorescent sensor based on poly[oligo(ethylene glycol) methyl ether methacrylate]-b-poly[N,N-diethylaminoethyl methacrylate-r-4-(2-methylacryloyloxyethylamino)-7-nitro-2,1,3-benzoxadiazole] [POEGMA-b-P(DEAEMA-r-NBDMA)], in which DEAEMA units act as the CO_2-responsive segment and 4-nitrobenzo-2-oxa-1,3-diazole(NBD) is the chromophore. The micelles composed of this copolymer could disassemble in 2 s upon CO_2 bubbling, accompanying with enhanced fluorescence emission with bathochromic shift. Furthermore,the quantum yield of the NBD chromophore increases with both the CO_2 aeration time and the NBD content. Thus we attribute the fluorescent enhancement to the inhibition of the photo-induced electron transfer between unprotonated tertiary amine groups and NBD fluorophores. The sensor is durable although it is based on "soft" materials. These micellar sensors could be facilely recycled by alternative CO_2/Ar purging for at least 5 times, indicating good reversibility.