Julolidine fluorescent molecular rotors as vapour sensing probes in polystyrene films

Abstract

We introduce a new sensing polymer system for detection of volatile organic compounds (VOCs) based\ud on the optical response of polystyrene (PS) films doped with julolidine fluorescent molecular rotors\ud (FMRs). The julolidine FMRs exhibited viscosity-dependent changes in the fluorescence intensity, that\ud was enhanced when glycerol was added to ethanol solutions and when they were dispersed in PS films.\ud Thus, reduction in medium mobility slowed down internal motions and allowed for a major radiative\ud decay pathway. The FMR/PS films were exposed to several VOCs, and showed a significant decrease in\ud fluorescence emission when exposed to chloroform, whereas a negligible variation in their emission\ud occurred when methanol was utilized. This vapour sensing behaviour was much more evident when a\ud perfluorodecyl chain was linked to the julolidine core being the molecule segregated at the film surface.\ud This responsive behaviour was affected by solvent composition and its reproducible response was easily\ud determined by luminescence experiments

Prolate and Temperature‐Responsive Self‐Assemblies of Amphiphilic Random Copolymers with Perfluoroalkyl and Polyoxyethylene Side Chains in Solution

“…Random copolymers based on the latter type of monomers have the advantage to be soluble in both water and organic solvents and to be thermally responsive in water solution, due to the occurrence of a lower critical solution temperature‐type (LCST) transition . The introduction of fluorinated comonomer units is known to drastically affect both bulk and surface properties of a copolymer, enhancing for example its ability to spontaneously organize at low energy surfaces and interfaces, both phenomena being driven by the lowest surface energy perfluorinated moieties . Amphiphilic random copolymers of PEGMA with fluoroalkyl methacrylates (FMA) were recently synthesized by ruthenium‐catalyzed living radical polymerization and shown to give rise to single‐chain self‐assemblies, referred to as unimer micelles, in water and 2 H ,3 H ‐perfluoropentane solutions …”

The self‐assembly over nano‐ to submicro‐length scales in water of a fluorescent julolidine‐labeled amphiphilic random terpolymer

“…An in‐depth characterization of the JCBF monomer was recently published . Briefly, UV–vis spectra of JCBF in chloroform solutions showed a characteristic absorption peak at around 407 nm ( ɛ = 21,500 M −1 ·cm −1 ), typical of cyanovinyl julolidine derivatives, and a second absorption peak at about 290 nm, due to the π → π * electronic transition of the biphenyl moiety. The fluorescence emission maximum was at around 500 nm ( λ exc = 410 nm) with a negligible fluorescence quantum yield ( Φ = 2.11·10 −3 ) due to the preferential formation, in low viscosity media, of the radiationless TICT excited state.…”

Vapochromic polyketone films based on aggregation‐induced enhanced emission

“…In addition, pressing issues in global security are triggering the design of novel chromogenic compounds aimed at detecting environment changes with optical responses even more effective. For example, thermoplastic indicators containing fluorophore sensitive to viscosity changes have been used with success for the detection of VOCs . Notably, plastic films containing moderate amounts of the chromophoric probe (<0.1 wt%) display fluorescence variations upon the exposure to well‐interacting VOCs due to an induced plasticization of the continuous polymer phase .…”

“…For example, thermoplastic indicators containing fluorophore sensitive to viscosity changes have been used with success for the detection of VOCs . Notably, plastic films containing moderate amounts of the chromophoric probe (<0.1 wt%) display fluorescence variations upon the exposure to well‐interacting VOCs due to an induced plasticization of the continuous polymer phase . Plasticization means also viscosity decreasing, thus allowing the dispersed fluorophores to aggregate together upon a certain concentration threshold, which in turn causes evident color changes.…”

“…[3][4][5][6][7][8][9][10][11][12] Notably, plastic films containing moderate amounts of the chromophoric probe (<0.1 wt%) display fluorescence variations upon the exposure to well-interacting VOCs due to an induced plasticization of the continuous polymer phase. [3][4][5][6]9,13 Plasticization means also viscosity decreasing, thus allowing the dispersed fluorophores to aggregate together upon a certain concentration threshold, which in turn causes evident color changes. In this context, the 4,4′-bis(2benzoxazolyl)stilbene (BBS) dye has been demonstrated to be an effective probe for the determination of polymer mechanical solicitations and thermal stress.…”