Synthesis, characterization and chemical sensor applications of pyrene side‐functional polylactide copolymers

Abstract

AbstractA novel polylactide (PLA) polymer containing pyrene side groups (P2) was synthesized and employed as a nitroaromatic compound (NAC) and heavy metal ion (HMI) sensing chemical probe. P2 was prepared in a four‐step reaction sequence, including azidification, esterification, ring opening polymerization and click reactions. First, an azido functional cyclic carbonate monomer (ADTC) was synthesized and then a copolymer of l‐lactide and ADTC monomers was synthesized to obtain PLA with azido functional groups (P(LA‐co‐ADTC), P1). Finally, P1 was modified with pyrene groups using ‘click chemistry’ which is a highly effective modification method (P2). The chemical structures and molecular characteristics of the obtained polymers were clearly verified via Fourier transform infrared spectroscopy, gel permeation chromatography and 1H NMR analysis techniques and the fluorescence properties were examined via UV–visible and fluorescence spectrometry. The prepared P2 polymers were employed as a fluorescent probe towards certain HMI (Zn2+, Hg2+, Mn2+, Pb2+, Cd2+, Co2+) compounds and NACs (1,2‐dinitrobenzene, 2,4‐dinitrotoluene, 2,4,6‐trinitrophenol (picric acid, PA), 4‐nitrophenol (4‐NP), 2,4‐dinitrophenol (2,4‐DNP), 2,4,6‐trinitrotoluene, 4‐nitrotoluene). The fluorescence intensity of the P2 polymers was gradually reduced upon the addition of NACs and HMIs. For all compounds, the highest quenching efficiencies were attained in the presence of PA (94.03%), 4‐NP (91.11%) and 2,4‐DNP (89.08%). Because of its simplicity and sensitivity, the proposed P2 polymers can be especially considered as potential chemical probes to detect NACs. © 2020 Society of Industrial Chemistry