An optical chemical sensor based on functional polymer films for controlling sulfur dioxide in the air of the working area: Acrylonitrile and alkyl methacrylate copolymers with brilliant green styrene sulfonate

Abstract

Sulfur dioxide (SO 2 ) belongs to the six major pollutants of atmospheric air [1] and ranks first in the mass of exhausts to the atmosphere. Therefore, studies on the development of methods for determining SO 2 in atmospheric air [2], including those with the use of optical chemical sensors (OCS) [3,4,5] are of high current importance.Among the sensing materials of SO 2 sensors are polycrystalline films [2], polymers with physically bound analytical reagents [4], and Langmuir-Blodgett layers [5]. Complexation reaction between SO 2 molecules and amino groups in molecules of analytical reagents is most often used as an analytical reaction. This reaction is well-known and often used for the extraction of SO 2 from waste gases [6]. In the previously developed optode [4], plasticized PVC films to which molecules of aromatic aldehydes, phenoxazine derivative as the main chromoionophore, and lipophilic alcohols were physically bound were studied as sensing materials. The reversible reaction of the bisulfite anion with aromatic aldehyde molecules followed by the detection of with an acid-base indicator was HSO 3 -HSO 3 -used as the working reaction. Analysis was performed using samples with specially controlled moisture content. The refractometric sensor based on LangmuirBlodgett layers exhibited linear calibration characteristics only in the range of rather high concentrations (500-1500 mg/m 3 ) [5].In recent years, particularly because of the rapid progress of biosensors, it has become evident that the most promising sensing materials are those in which molecules of analytical reagents or basic fragments of such molecules are chemically bound to matrix materials by covalent of ionic bonds. From the viewpoint of the stability of sensor characteristics and therefore, the practical application of OCSs, functional polymers undoubtedly offer most promise among the polymeric materials [7]. In these polymers, fragments of analytical reagents are chemically (via covalent or ionic bonds) bound to the polymer chain. In addition to the thermodynamic stability of sensing materials and the stability of sensor characteristics in time, functional polymers exhibit one more merit. This merit is the possibility of purposeful molecular design (synthesis) of materials with the specified gas-adsorption and sensing properties. It should also be noted that all the aforesaid ARTICLES Abstract-The effects of the chemical and phase composition of acrylonitrile and alkyl methacrylate (Alkyl-MA) copolymers with styrene sulfonates (SS) of triphenylmethane dye cations on the gas permeability and sensing properties of their films were studied for developing an optical chemical sensor (OCS) for sulfur dioxide (SO 2 ) on the basis of functional polymers. Of the three triphenylmethane dyes tested, namely, fuchsine, Crystal Violet, and Brilliant Green (BG), only the last dye was selected for molecular design. It was shown that the copolymer of Decyl-MA with SS-BG with the degree of modification DM = 0.10 is the best material among the studied ones from ...

An Optical Chemical Sensor Based on Functional Polymer Films for Controlling Sulfur Dioxide in the Air of the Working Area: Polydimethylsiloxane Copolymers with Ionically Bound Brilliant Green Cations

“…A comparison of the sensitivities and the times absorbance attained its steady-state value upon the admittance of a gas ( t ss ) for films of polyacrylates of different chemical structures indicates that the gas-permeability of the polymers increases with a decrease in the length of the elementary link of the polymer; for polymers of equal chain lengths (PA-1 and PA-2), gas-permeability increases with an increase in the concentration of sulfonate groups in the macromolecule chain in the order PA-1 < PA-2 < PA-3. A similar dependence of sensitivity on the degree of modification was observed for allyl methacrylate-BG-styrene sulfonate copolymers in [1]. The regeneration of the initial electronic absorption spectra of polymers under mild conditions (by blowing samples with pure air at room temperature) pointed to the complete reversibility of the adsorption of SO 2 .…”

“…As in [1], we took relative changes in absorbance at the long-wavelength absorption maximum ∆ A , % as the sensitivity of electronic absorption spectra to the action of SO 2 . SO 2 was admitted to samples of films of approximately equal thicknesses (0.3 µ m) annealed at room temperature (Table 1) until pressure reached 1 atm.…”

“…In our previous paper [1], we presented the results of studying the effect of SO 2 on the electronic absorption spectra of thin films fabricated of functional polymers from two classes. These polymers were copolymers of acrylonitrile ad alkyl methacrylates with styrene sulfonates of triphenylmethane dyes, in particular, Brilliant Green (BG).…”

“…First, we studied the effect of SO 2 on the electronic absorption spectra of films in vacuum and compared the sensitivities of the studied functional polymers with those of the previously studied polymers [1]. Next, for films of ionogenic PDMSs of different thicknesses, we obtained calibration functions in a wide range of SO 2 concentrations in an air flow.…”

“…The samples were made glass of quartz disks 27 or 30 mm in diameter and 3 mm in thickness, onto which homogeneous thin films of polymers were applied from DMFA solutions using centrifugation (details were described in [1]). To remove the solvent, the samples were placed in a VUP-5 universal vacuum station evacuated to a residual pressure of 2 × 10 -6 mm Hg for several hours.…”