Highly Tunable Nanostructures in a Doubly pH-Responsive Pentablock Terpolymer in Solution and in Thin Films

Multiblock copolymers with charged blocks are complex systems that show great potential for enhancing the structural control of block copolymers. A pentablock terpolymer PMMA-b-PDMAEMA-b-P2VP-b-PDMAEMA-b-PMMA is investigated. It contains two types of midblocks, which are weak cationic polyelectrolytes, namely poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and poly(2-vinylpyridine) (P2VP). Furthermore, these are end-capped with short hydrophobic poly(methyl methacrylate) (PMMA) blocks in dilute aqueous solution and thin films. The self-assembly behavior depends on the degrees of ionization α of the P2VP and PDMAEMA blocks, which are altered in a wide range by varying the pH value. High degrees of ionization of both blocks prevent structure formation, whereas microphase-separated nanostructures form for a partially charged and uncharged state. While in solutions, the nanostructure formation is governed by the dependence of the P2VP block solubility of the and the flexibility of the PDMAEMA blocks on α, in thin films, the dependence of the segregation strength on α is key. Furthermore, the solution state plays a crucial role in the film formation during spin-coating. Overall, both the mixing behavior of the 3 types of blocks and the block sequence, governing the bridging behavior, result in strong variations of the nanostructures and their repeat distances

Characterization of 1,7-dibromo-N,N'-(bicyclohexyl)-3,4:9,10-perylendiimide Langmuir-Blodgett film for organic vapor sensing application

1,7-Dibromo-N,N'-(bicyclohexyl)-3,4:9,10-perylendiimide material (FY3) was used as a sensor element in this work. Different number of LB thin film layer was deposited onto a gold-coated glass substrate to produce a thin film sensor element. Fabrication processes were monitored by surface plasmon resonance (SPR) technique. The experimental SPR data were fitted using the Winspall software to evaluate the film thickness and refractive index of this material. Values of the thickness and refractive index of LB films were determined as 0.54 ± 0.01 nm for the thickness per monolayer, and 0.46 ± 0.08 for the refractive index. LB thin film sensor element was exposed to chloroform, benzene, toluene and ethyl alcohol vapors. In-situ SPR measurements showed that the response of the FY3 LB film for saturated chloroform vapor is much larger than the other vapors with 4 s recovery times and 5 s response time. The photodetector response change, ?I rf was monitored when FY3 LB film was exposed to these organic vapors and the response of the FY3 LB film to chloroform was also the largest among organic vapors with the ?I rf value of 0.11 au. It can be proposed that this sensing element deposited onto gold-coated glass substrates has a good sensitivity and selectivity for saturated chloroform vapor. © 2015 Elsevier B.V. All rights reserved

Optical characterization and swelling behaviour of Langmuir–Blodgett thin films of a novel poly[(Styrene (ST)-co-Glycidyl Methacrylate (GMA)]

In this study, FTIR, Raman,1H-and13C NMR spectral studies, thermogravimetric analyses (TGA), UV–vis spectroscopy, atomic force microscopy (AFM), surface plasmon resonance (SPR) and quartz crystal microbalance (QCM) measurements are used for copolymer characterization. A novel poly[(Styrene (ST)-co-Glycidyl Methacrylate (GMA)] is used to fabricate Langmuir-Blodgett (LB) thin films for the purpose of investigating its gas sensing properties. The thickness of this copolymer LB film, determined by the slope of the thickness versus layer number, is found to be 0.99 ± 0.08 nm per monolayer. QCM and SPR systems are used to investigate gas sensing performance of copolymer LB films during exposure to Volatile Organic Compounds (VOCs). The changes in resonance frequency associated with mass changes can be attributed to the swelling behaviour of copolymeric thin films during vapor absorption. Fick's law for early-time diffusion was adopted to quantify real time QCM data for the swelling processes. It was observed that diffusion coefficients (D) for swelling obeyed the t1/2law and could be correlated with the VOCs used. The response of copolymer films to the chosen VOCs has been investigated, and the films were largely sensitive to dichloromethane vapor. © 2016 Elsevier B.V

Optical and Vapor Sensing Properties of Calix[4]arene Langmuir-Blodgett Thin Films with Host–Guest Principles

25,27-(Dipropylmorpholinoacetamido)-26,28-dihydroxycalix[4]arene was used as a chemical sensor material in this work. The calix[4]arene LB thin films were prepared onto a gold-coated glass and quartz glass substrates to fabricate a thin film chemical sensor element. Atomic Force Microscopy (AFM) and Surface Plasmon Resonance (SPR) techniques were used to characterize all the calix[4]arene LB thin films. The film thickness and the refractive index of thin films can be evaluated with the fitted experimental SPR datas. The refractive index and the thickness per monolayer of LB films were determined as a 1.58 ± 0.04 and 1.27 ± 0.09 nm, respectively. The calix[4]arene LB thin film chemical sensor element was exposed to dichloromethane, chloroform, benzene and toluene vapors. The SPR kinetic measurements displayed that, the photodetector response change, ?Irf for saturated dichloromethane vapor is much larger than the other vapors with the ?Irf value of 48 au and the diffusion coefficient value of 5.1 × 10?16 cm2s?1. Swelling process was analyzed by well known Fick's Equations. In this approach diffusion coefficients (D) for swelling were conformed to the square root of time and were correlated with the volatile organic compounds. Our results showed that calix[4]arene thin film has a highly selective with a large response to dichloromethane vapor. © 2018, © 2018 Taylor & Francis Group, LLC.UBAP 2017/HD-MF001This work was supported by the Research Foundation of Usak University (UBAP 2017/HD-MF001). We also thank Usak University Scientific Analysis Technological Application and Research Center (UBATAM) for their support

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

Determination of organic vapor sensing properties of ?-Naphthylmethacrylate (?-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 ?-NMA materials by using UV-Visible, Atomic Force Microscopy (AFM) and Quartz Crystal Microbalance (QCM) techniques. ?-A isotherm graph was taken and a suitable surface pressure value were primarily determined as 13 mN m?1 for successful ?-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 ?-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 ?-NMA LB thin films were potential candidates for organic vapor sensing applications, especially high sensitive detection of dichloromethane at room temperature. © 2019, © 2019 Taylor & Francis Group, LLC.216Z080The authors acknowledge The Scientific and Technical Research Council of Turkey (TUBITAK) for its financial support (Project No. 216Z080)

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, 1 H and 13 C 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. © 2019 Elsevier Ltd2018/MF002The financial support from the Research Foundation of Usak University (Project No: 2018/MF002 ) is gratefully acknowledged. Additionally, we thank UBATAM (Usak University, Scientific Analysis Technological Application and Research Center) for analyses. Appendix

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

In this work, the Langmuir–Blodgett (LB) technique was applied onto the different substrates such as quartz, quartz crystals and gold coated glass for fabricating LB thin films with 25,27-(Dipropylmorpholinoacetamido)-26,28-dihydroxycalix[4]arene. The characteristics of the calix[4]arene LB films were evaluated by UV–Vis, atomic force microscopy (AFM), quartz crystal microbalance (QCM) and surface plasmon resonance (SPR) measurements. The mass deposited on the quartz crystal per bilayer was predicted as 2028.80 ng (7.65 ng mm?2) for the calix[4]arene LB film. The sensing abilities of this LB film towards the development of room temperature organic vapor sensing devices were also examined. QCM and SPR systems were fixed to investigate vapor sensing performance of macrocyclic LB films during exposure to volatile organic compounds (VOCs). The macrocyclic LB thin films were more sensitive to dichloromethane than other vapors. The sensitivity and detection limit values of the calix[4]arene QCM sensor to dichloromethane vapor were calculated as 2.023 Hz ppm?1 and 1.482 ppm, respectively. The sensitivities of the calix[4]arene LB films against organic vapors can be explained with the host–guest interaction between the cavity of molecule and the organic vapor molecules. It is determined that the calix[4]arene LB film is more sensitive to dichloromethane than other vapors at room temperature and the calix[4]arene is a promising material serving as a vapor sensing device. © 2017, Springer Science+Business Media B.V.UBAP 2017/HD-MF001Acknowledgements This work was supported by the Research Foundation of Usak University (UBAP 2017/HD-MF001). We also thank Usak University Scientific Analysis Technological Application and Research Center (UBATAM) for their support