Fabrication and characterization of calix[4]arene Langmuir–Blodgett thin film for gas sensing applications

Microwave irradiation has been found to be a highly efficient method for etherification of p-tert-butylcalix[4]arene with alkyl bromides or ditosylate. The corresponding products were obtained as a pure form in modest yield within short reaction time when the reactions were performed under microwave irradiation.     

Spun films of perylene diimide derivative for the detection of organic vapors with host–guest principle

The optical characterization and chemical vapor sensing properties of 1,7-dibromo-N,N′-(bicyclohexyl)-3,4:9,10-perylene diimide thin film against to organic vapors were discussed in this study by using spin coating, UV–Vis spectroscopy, atomic force microscopy, surface plasmon resonance (SPR) and Quartz Crystal Microbalance (QCM) techniques. The perylene diimide thin films were fabricated with a refractive index values from 1.55 to 1.60 and thicknesses in the range between 15.80 and 26.32 nm using different spin speeds from 1000 to 5000 rpm. In this study, perylene diimide thin film sensor was exposed to dichloromethane, chloroform, carbon tetrachloride, tetrahydrofuran and ethyl acetate vapors by using both SPR and QCM techniques. Also, the swelling behaviors of the perylene diimide thin films prepared at different spin speeds were investigated with respect to dichloromethane vapor at the room temperature by using SPR data. Diffusion coefficients were found to be 11.34?×?10^?17 (1000 rpm), 2.56?×?10^?17 (3000 rpm) and 0.38?×?10^?17 cm² s^?1 (5000 rpm) for dichloromethane vapor by using the Fick’s law of diffusion. It might be proposed that perylene diimide thin film optical chemical sensor element has a good sensitivity and selectivity for the dichloromethane vapor at room temperature.     

Characterization of N-cyclohexylmethacrylamide LB thin films for room temperature vapor sensor application

This study reports the synthesis, characterization and gas sensing applications of N-cyclohexylmethacrylamide (NCMA) monomer material using FT-IR, ¹H and ¹³C NMR, UV-visible spectroscopy, Quartz Crystal Microbalance (QCM) and Langmuir-Blodgett (LB) thin film deposition techniques. The thin film deposition conditions of NCMA monomer material, which are prepared by LB film technique, are characterized by UV-visible spectroscopy and QCM system. The sensing behaviors of the LB film with respect to volatile organic compounds (VOCs) at room temperature are investigated. Surface pressure change as a function of surface area of NCMA molecule at the water surface shows a well-organized and stable monolayer at 18 mN m^?1 surface pressure value for LB film deposition. Transfer ratio values are found to be ≥ 0.94 for quartz glass and ≥ 0.93 for quartz crystal substrate. The typical frequency shift per layer is obtained 20.10 Hz/layer and the deposited mass onto a quartz crystal is calculated as 824.62 ng/layer. The sensing responses of the LB films against chloroform, dichloromethane, acetone, toluene, benzene and ethanol are measured by QCM system. The sensitivities of the NCMA LB film sensor are determined between 0.085 and 0.029 Hz ppm^?1. Sensitivities with detection limits are between 35.29 and 100.33 ppm against organic vapors. These results can be concluded that the monomer LB film sample is found to be significantly more sensitive to chloroform and dichloromethane vapors than others organic vapors used in this work. This material may find potential applications in the development of room temperature organic vapor sensing.     

Organic vapor sensing properties of copolymer Langmuir-Blodgett thin film sensors

In this study, a novel poly[Styrene (ST)-co-Glycidyl Methacrylate (GMA)] copolymer material is used to fabricate Langmuir-Blodgett (LB) thin films and investigate organic vapor sensing properties. Quartz Crystal Microbalance (QCM) system is used to investigate gas sensing performance of copolymer LB films during exposure to Volatile Organic Compounds (VOCs). The poly[Styrene (ST)-co-Glycidyl Methacrylate (GMA)] LB thin film sensor sensitivities are determined to be between 0.12 and 0.25 Hz ppm^?1. Detection limits of the copolymer LB thin film are found to be between 23 and 49 ppm against organic vapors. The copolymer LB thin films are more sensitive to chloroform than other vapors used in this study. The results demonstrated that the poly[Styrene (ST)-co-Glycidyl Methacrylate (GMA)] copolymer material is promising as a organic vapor sensing device at room temperature.     

Calix[4]arene-triazine conjugate intermediate: optical properties and gas sensing responses against aromatic hydrocarbons in Langmuir–Blodgett films

Research on Chemical Intermediates - The detection of organic vapors by chemically based sensors was achieved with macromolecules having convenient molecular cavities. Addressed herein, a...     

A novel triazine‒bearing calix[4]arene: Design,synthesis and gas sensing affinity for volatile organic compounds

A novel triazine-calix[4]arene conjugate was designed and synthesized with the aim to study gas sensing against volatile organic compounds (VOCs) such as dichloromethane, chloroform and carbon tetrachloride. This novel compound was fully characterized by spectroscopic techniques such as FTIR, ¹H and ¹³C NMR along with HRMS and BET analysis. The triazine based calix[4]arene organic materials were fabricated onto quartz glasses and quartz crystal substrates to form a thin film chemical sensor element by using Langmuir-Blodgett (LB) technique. Quartz Crystal Microbalance, UV–Visible Spectroscopy, Atomic Force Microscopy and Scanning Electron Microscopy techniques were employed to characterize all these LB thin film layers. Fick's Equations were used for analyzing the swelling process of LB thin film sensor and diffusion coefficient values of organic vapours for swelling were obtained. The initial experiments have revealed that new triazine appended calix[4]arene derivative exhibited an effective chemical gas sensor characteristic with a large response to dichloromethane vapour.     

Organic vapor sensing properties and characterization of α-naphthylmethacrylate LB thin films

Determination of organic vapor sensing properties of α-Naphthylmethacrylate (α-NMA) monomer based Langmuir-Blodgett (LB) thin films was aimed in this study. LB thin film fabrication was performed on quartz glass and quartz crystal substrates in order to investigate the characterization and organic vapor properties of α-NMA materials by using UV-Visible, Atomic Force Microscopy (AFM) and Quartz Crystal Microbalance (QCM) techniques. π-A isotherm graph was taken and a suitable surface pressure value were primarily determined as 13?mN m^?1 for successful α-NMA LB thin film fabrication. Transfer ratio value was found to be ≥ 0.93 for quartz glass and quartz crystal substrates. The typical frequency shift per layer was obtained as 16.93?Hz/layer and the deposited mass onto a quartz crystal was calculated as 271.30?ng/layer (1.02?ng mm^?2). The sensing responses of α-NMA LB films against dichloromethane, chloroform, toluene and m-xylene were measured by QCM system. Dichloromethane created the maximum shift in the resonance frequency than other organic vapors used in this study. Results exhibited that α-NMA LB thin films were potential candidates for organic vapor sensing applications, especially high sensitive detection of dichloromethane at room temperature.     

Characterization of PDPA-b-PDMA-b-PDPA triblock copolymer Langmuir-Blodgett films for organic vapor sensing application

This study reports the synthesis, characterization, and gas sensing applications of the PDPA-b-PDMA-b-PDPA triblock copolymer material using NMR, UV-visible spectroscopy, atomic force microscopy (AFM), quartz crystal microbalance (QCM), and Langmuir-Blodgett (LB) thin film deposition techniques. The thin film deposition conditions of the copolymer material, which are prepared by LB film technique, are characterized by UV-visible spectroscopy, AFM, and QCM system. In this study, the swelling behaviors of the PDPA-b-PDMA-b-PDPA triblock copolymer Langmuir-Blodgett (LB) films were investigated with respect to volatile organic compounds (VOCs) at room temperature. The sensing responses of the films against VOCs were measured by QCM method. The swelling processes could be investigated using the early-time Fick's law of diffusion.     

Recent progress in pillar[n]arene-based thin films on chemical sensor applications

Journal of Inclusion Phenomena and Macrocyclic Chemistry - Pillar[n]arene is one of the most favorited supramolecular materials that possess a special chiral structure. The major property of...