Aggregation induced emission (AIE) active cross-linked poly(-isopropyl acrylamide--tetra(phenyl)ethene di-acrylates): sensors for effective nitroaromatics detection in an aqueous environment

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2022-04, Vol.1 (15), p.5856-5863
• Main Authors: Liu, Feng, Ren, Yi, Lau, Hazel, Tang, Ben Zhong, Zhou, Hui
• Format: Article
• Language: English
• Subjects: Acrylamide; Acrylates; Agglomeration; Aqueous environments; Copolymerization; Copolymers; Crosslinking; Emission; Ethylene; Glass transition temperature; Nitrotoluene; Polydispersity; Polyisopropyl acrylamide; Thermal stability; Trinitrotoluene
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/d1tc06068f

Aggregation induced emission (AIE) active cross-linked copolymers CP1-4 with high molecular weights (12 700-14 100) and low polydispersity indices (1.2-1.3) were prepared through copolymerization of N -isopropyl acrylamide (NIPAM) and tetra(phenyl)ethene (TPE)-based acrylate dimers. CP1-4 show comparable thermal stability to poly( N -isopropylacrylamide) (PNIPAM), while their glass transition temperatures are higher by 11-13 °C than that of pristine PNIPAM. CP1-4 are soluble in common organic solvents and water. They are thermally sensitive like PNIPAM, with reduced lower critical solution temperatures (LCSTs) associated with higher TPE content. CP1-4 show typical AIE properties, which are similar to those of reported linear copolymers LP1-4 . The fluorescence of CP1-4 in pure water could be significantly quenched by a wide range of nitroaromatics, including picric acid (PA), 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (DNT) and 4-nitrotoluene (NT). Nevertheless, the detection sensitivity of CP1-4 could be greatly improved through a collapsing-swelling process, in which the formation and interaction of non-covalent bonding between TPE groups and nitroaromatic molecules are significantly enhanced, resulting in reduced detection levels as low as 0.25 μg mL −1 or 0.25 ppm. Thus, CP1-4 has the potential for highly sensitive detection of a variety of nitroaromatics in aqueous environments. The fluorescence of AIE active polymer CP1-4 in water could be quenched by many nitroaromatics. The detection sensitivity of CP1-4 could be greatly improved to the levels as 0.25 ppm by a collapsing-swelling process.