Poly(methyl methacrylate) films for organic vapour sensing (original) (raw)
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TECHNICAL NOTE: Spun thin films of poly(methyl methacrylate) polymer for benzene sensing
Smart Materials & Structures, 2005
Thin films of poly(methyl methacrylate) (PMMA) were deposited on suitably prepared substrates by spinning the spreading solution in chloroform at 3000 rpm for atomic force microscopy and surface plasmon resonance studies. Four different types of PMMA were used within a range of molecular weight between 540 and 760 kg mol-1. The film surface was found to be uniform. Values of refractive index for PMMA film were found to exist in the range of 1.50 ± 0.04 to 1.53 ± 0.02. All films exhibited fast response to the exposure of benzene vapour but the sensitivity of detection depended upon the molecular weight.
Spun thin films of poly(methyl methacrylate) polymer for benzene sensing
Smart Materials & Structures, 2005
Thin films of poly(methyl methacrylate) (PMMA) were deposited on suitably prepared substrates by spinning the spreading solution in chloroform at 3000 rpm for atomic force microscopy and surface plasmon resonance studies. Four different types of PMMA were used within a range of molecular weight between 540 and 760 kg mol −1 . The film surface was found to be uniform. Values of refractive index for PMMA film were found to exist in the range of 1.50 ± 0.04 to 1.53 ± 0.02. All films exhibited fast response to the exposure of benzene vapour but the sensitivity of detection depended upon the molecular weight.
An Optical Vapor Sensor Based on Amphiphilic Block Copolymer Langmuir–Blodgett Films
IEEE Sensors Journal, 2018
Amphiphilic block copolymers containing poly [N,N-(dimethylamino)ethyl methacrylate] block was used as a chemical sensor material in this paper. The amphiphilic block copolymer Langmuir-Blodgett (LB) thin films were prepared onto a gold-coated glass, quartz crystal and quartz glass substrates to fabricate a thin film chemical sensor element. Atomic force microscopy, quartz crystal microbalance, UV-visible spectroscopy, and surface plasmon resonance (SPR) techniques were used to characterize all the copolymer LB thin films. The mass deposited onto a quartz crystal and the frequency shifts per layer were found to be 4258.01 ng per layer (16.06 ng mm −2) and 188.07 Hz per layer, respectively. Using Winspall software, all experimental SPR data were fitted and the film thickness of this the copolymer LB thin film can be evaluated. The refractive index and thickness per monolayer of LB films were determined as 1.63 ± 0.02 nm and 1.46 ± 0.07 nm, respectively. Amphiphilic block copolymer LB thin film chemical sensor element was exposed to dichloromethane, chloroform, benzene, and toluene vapors. The SPR kinetic measurements showed that the photodetector response change, I rf for saturated dichloromethane vapor is much larger than the other vapors with the I rf value of 0.081 au and with 3.5-s recovery time/4.5-s response time. It can be proposed that amphiphilic block copolymer LB thin film chemical sensor element has a good sensitivity and selectivity for saturated dichloromethane vapor.
Thin Solid Films, 2008
Thin films of azo-calix[4]resorcinarene (AZO) and poly(9-vinylcarbazole) (PVK) have been deposited by the method of spin coating and are studied for the optical detection of volatile organic vapour molecules. Both types of films were exposed to a range of concentrations of the vapours of benzene, toluene, n-hexane, m-xylene, and 1-butanol, and films' interaction with the above molecules was monitored using surface plasmon resonance (SPR) method. The films optical parameters change as a result of such interaction; these changes were determined from the theoretical data fitting of the measured SPR curves. The reflection intensity was also monitored as a function of time at a fixed angle of incidence near the reflectivity minima of the SPR curves. Mechanism of interaction with the studied vapour molecules is discussed in terms of capillary condensation of the vapour molecules inside the nanoporous matrix of PVK and AZO films. The films' responsivity is found to correlate with the solubility of AZO and PVK molecules in the above solvents.
Analytical and Bioanalytical Chemistry, 2002
In order to simplify the procedure for assembling a surface-plasmon resonance (SPR) sensor, a refractive index matching polymer film was prepared as an alternative to the conventionally used matching oil. The refractive index matching polymer film, the refractive index of which was nearly equal to the prism and sensor chip material (a cover glass) of the SPR sensor, was prepared by casting a tetrahydrofuran solution of poly (vinyl chloride) (PVC) containing equal weights of dioctyl phthalate and tricresyl phosphate. The refractive index matching polymer film was found to have a refractive index of 1.516, which is identical to that of the prism and the cover glass used for the present SPR sensor. The utility of the matching polymer film for the SPR sensor was confirmed by the detection of anti-human albumin, based on an antigen-antibody reaction.
A STUDY on the sensitivity and selectivity properties of Polymer based gas-vapor sensors
Journal of the Turkish Chemical Society, Section A: Chemistry, 2016
In this study, the water soluble poly (diphenylaminesulfonic acid) (PSDA) and the diblock copolymer of PSDA with poly(ethylene glycol) (PEG) were used to construct the interdigitated film electrodes (IDEs). Their responses against humidity and various solvent vapors were investigated by impedance measurements. Sorption and desorption behaviors of the solvents were determined by simultaneous registration of the impedance (Z) and the resistive (R, resistance) and capacitive (X, reactance) components of the Z under different potential bias and alternating current (ac) frequencies. The sensor responses were discussed considering the polar/non-polar and polarizability properties of the polymers and solvents. The effect of ac frequency and potential bias on the sensitivity and selectivity of the sensors were discussed. It was found that the solvent polarity is the primary effect on the electrical conductance and capacitance of both PSDA homopolymer and PSDA-b-PEG block copolymer. The results supported that the dipolarity-polarizability properties of solvents have also a critical role on sensor response at low ac frequencies. The more polarizable solvents gave higher sensor responses at lower ac frequencies. The equilibrium response of the PSDA based sensor was correlated with the dielectric constant of the solvents. The values of Z and R of PSDA film under saturated solvent vapors at 1 kHz ac frequency were linearly correlated (R 2 was 0.955, 0.993 and 0.957 for Z, R and X, respectively, in semi-logarithmic scale) with the values of the dielectric constants of the solvents, except water. A similar correlation (R 2 = 0.996) was obtained by using the R values of the PSDA film at 100 kHz ac frequency. In the case of PSDA-b-PEG polymer film, it was also possible to establish an almost linear correlation (R 2 =0.943) between the R at 100 kHz ac frequency and the values of the dielectric constants of the solvents, except acetone and water. Consequently, it was found that the applied ac frequency was distinctive on both the sensitivity and selectivity of the studied sensor.
The 6th International Electronic Conference on Sensors and Applications, 2019
Hydrophobically modified poly(vinyl alcohol)s of varied copolymer composition were tested as active media for optical sensing of humidity. Copolymer thin films were deposited on silicon substrate using water-methanol solution in a volume ratio of 20:80 and concentration of 1 wt%. Films were subjected to low (60 °C) and moderate (180 °C) temperature annealing in order to study the temperature influence on optical and humidity sensing properties. Refractive index, extinction coefficient along with thickness of the films were determined by non-linear minimization of the goal function comprising measured and calculated reflectance spectra at normal light incidence. The humidity sensing ability of the films was studied through reflectance measurements at different humidity levels in the range 5–95 %RH. The influence of temperature annealing on optical and sensing properties was demonstrated and discussed.
Sensors and Actuators B: Chemical, 2007
The optical sensing properties of nanometric polyimide films towards ethanol and methanol vapours have been investigated by surface plasmon resonance technique. To this purpose polyimide sensing layers have been deposited onto gold/glass substrates by glow-discharge-induced vapour deposition polymerization technique. The sensible layer shows reversible and stable responses to different concentrations of methanol and ethanol vapours. A linear dependence between the change in reflectivity and the vapours concentration is observed being the sensitivity to both vapours similar, however, the response is larger in presence of ethanol vapours. Numerical fitting routines on surface plasmon resonance curves indicate that optical changes are motivated by an absorption process of the analyte. This produces a detectable increase of the real refractive index and a swelling process in the polyimide layer. Julián Fernández).
Thin solid films, 1998
Aromatic hydrocarbon sensing has been successfully demonstrated using surface plasmon resonance (SPR) with Langmuir-Blodgett (LB) films of a 5,5′-methylenebis (N-hexadecylsaliclidenamine) Schiff base complex. The LB layers were exposed to concentrations of benzene, toluene, ethanol and water vapours. This resulted in a reversible shift in the resonance depth and position of the SPR curves. The co-ordination polymer was found to be most sensitive to benzene and could reliably detect concentrations of this vapour down to 100 vapour parts per million.