Compensation for the influence of temperature and humidity on oxygen diffusion in a reactive polymer matrix (original) (raw)
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A new technique to quantify oxygen diffusion in polymer films
Macromolecules, 1992
Diffusion Coefficients for oxygen in polymer films are quickly and accurately obtained by using a near-infrared luminescence spectrometer. The spectroscopic technique described herein uses the 1270-nm phosphorescence of singlet molecular oxygen (l $ 0 2-32,-02) to directly monitor oxygen sorption into polymer films (15-80 Fm thick) of small area (-1 cm X 1 cm). The approach is illustrated by using films of polystyrene for which a 25 "C diffusion coefficient of (2.3 f 0.3) x cm2/s is obtained.
Journal of Food Engineering, 2016
An optical sensor for oxygen detection based on the immobilization of tris 1,10-phenanthroline ruthenium (Ru(phen) 3) into polystyrene (PS) films was employed for monitoring the oxygen permeation through polymeric packaging films. 7-Methoxy-4-methylcoumarin was selected as non-sensitive reference to oxygen and dispersed with the Ruthenium complex in order to develop a ratiometric sensor correcting the artefacts induced by operating conditions and improving the robustness of the sensor. The developed ratiometric sensor was successfully employed for the measurement of the oxygen permeation rate in an enclosed atmosphere (package) using polymeric films made of biaxially oriented polypropylene (BOPP) and polydimethyl siloxane (PDMS). It was observed that the oxygen concentration in the enclosed atmosphere increased from 0% to 21% in 3 hours in the case of PDMS and from 0% to 3.6% in 24 hours for BOPP. The concentration evolvement with time was well predicted by a solutiondiffusion model and the final oxygen concentration in the packed atmosphere was confirmed by chromatographic measurements. According to these results, the ratiometric luminescent sensor is suitable for the development of smart packaging films allowing for continuous monitoring of oxygen concentration in-situ. Highlights • Development of robust ratiometric luminescent sensor • Non-invasive and on-line monitoring of oxygen in food packaging • In-situ measurement of oxygen permeation trough packaging materials • Predicting oxygen concentration in food packaging using molecular probes
Journal of Packaging Technology and Research
An attempt was made in the present study to develop and characterize sodium alginate (SA-MB-NR), sodium caseinate (SC-MB-RSS), and carrageenan (CG-MB) ultraviolet light activated intelligent oxygen indicator. Among all the sensor films, CG-MB displayed least overall migration in all the food simulants. Tensile strength of CG-MB sensor film was found to be the highest among all. FTIR spectra of the original and photo-activated sensor films revealed changes in the alkyl, amide, and hydroxyl groups. Equilibrium moisture content of the sensor films was found to be in the range of 94.73-120.26 g 100 g −1. Peleg model was found to best describe the sorption behaviour of SA-MB-NR while SC-MB-RSS and CG-MB were best described by D'Arcy and Watt model. All the three sensor films were found to be equally sensitive to oxygen concentration varying from 2 to 10% but significantly differed at 1% (P < 0.05). All the three sensor films were found to be equally sensitive to oxygen at as low as below 1% concentration. Hence, it can be concluded that film CG-MB could be potentially applied as an oxygen leak indicator for direct contact (vacuum) or non-direct contact (modified atmosphere) food-packaging applications.
Oxygen sensors based on the ionically conductive polymer poly(dimethyldiallylammonium chloride)
Sensors and Actuators B: Chemical, 1992
Graphite rods coated with poly(dimethyldiallylammonium chloride), poly(DMDAAC), and subjected to immobilization by 7-irradiation have been shown to respond linearly to dissolved oxygen concentration. The oxygen is detected electrochemically by reduction at a potential of-0.40 V versus Ag/AgCI. The concentration range of linearity investigated is 1.4 to 9.3 ppm. The polymer-coated electrode has a sensitivity of 12.5 taA cm-2 ppm-', a detection limit of 1.4 ppm and a response time of 5 min or less. Poly(DMDAAC) also provides the electrode surface with some protection against adsorbing species during the measurement. Further, poly(DMDAAC) can function as the electrolyte in a solid-state cell and allows electrochemical measurements to be made in air in the absence of a supporting electrolyte solution. The response to oxygen concentration in the surrounding atmosphere is shown.
Very fast sensors that are able to track rapid changes in oxygen partial pressure (PO2) in the gas and liquid phases are increasingly required in scientific research – particularly in the life sciences. Recent interest in monitoring very fast changes in the PO2 of arterial blood in some respiratory failure conditions is one such example. Previous attempts to design fast intravascular electrochemical oxygen sensors for use in physiology and medicine have failed to meet the criteria that are now required in modern investigations. However, miniature photonic devices are capable of meeting this need. In this article, we present an inexpensive polymer type fibre-optic, oxygen sensor that is two orders of magnitude faster than conventional electrochemical oxygen sensors. It is constructed with biologically inert polymer materials and is both sufficiently small and robust for direct insertion in to a human artery. The sensors were tested and evaluated in both a gas testing chamber and in a flowing liquid test system. The results showed a very fast T90 response time, typically circa 20 ms when tested in the gas phase, and circa 100 ms in flowing liquid.
A New Diffusion Cell for Characterizing Oxygen Permeation of Fiber Reinforced Polymers
The gas diffusion characterization of polymers is important in many industries. For example, in the food packaging industry, it establishes the product guarantee period for food contained in hermetically sealed polymer wrapping. As a result, several methods are available for measuring gas diffusion characteristics of polymers. Unfortunately, they are not particularly suited for evaluating the much thicker polymers used in infrastructure applications such as fiber reinforced polymers. This paper describes the development of a new diffusion cell and an associated testing technique that makes it possible to characterize thicker polymer films as well as composite systems in which polymers are bonded to non-polymers such as concrete. It provides information on the background and basis of the new testing system including detailed descriptions, data collection and testing protocol.
The Journal of Chemical Physics, 2015
Up until now, gas permeation through polymers under high pressure has not been able to be measured continuously. The combination of a special high pressure cell and a commercially available fluorescence-based oxygen measurement system allows in-situ monitoring of oxygen permeation through a polymer sample under pressure in an aqueous environment. The principle of the oxygen sensor is based on dynamic fluorescence quenching and measurement of the fluorescence decay time. It was observed that the decay time increases non-linearly with the applied pressure, and hence, the displayed oxygen concentration has to be corrected. This deviation between the measured and the real concentration depends not only on the pressure but also on the absolute oxygen concentration in the water. To obtain a calibration curve, tests were performed in the pressure range between 1 and 2000 bars and initial oxygen concentrations in the range between 40 and 280 µmol/l. The polynomial calibration curve was of the fourth order, describing the raw data with a coefficient of determination R 2 > 0.99. The effective oxygen permeation through polymeric samples can be calculated with this function. A pressure hysteresis test was undertaken but no hysteresis was found. No temperature dependence of the oxygen sensor signal was observed in the range between 20 • C and 30 • C. This study presents for the first time data showing the oxygen permeation rates through a polyethylene film in the pressure range between 1 and 2000 bars at 23 • C.
Chemistry of Materials, 2010
A new oxygen sensor, compound 2, was synthesized through a chemical modification of a popularly used oxygen sensor of platinum(II)-5,10,15,20-tetrakis-(2,3,4,5,6-pentafluorophenyl)-porphyrin (PtTFPP). The new sensor compound 2 possesses four crosslinkable methacrylate functional moieties, enabling it to be polymerized and crosslinked with other monomers for polymer sensing film (also called membrane) preparation. Using this characteristic, compound 2 was covalently bonded to hydrophilic poly(2-hydroxyethyl methacrylate)-co-polyacrylamide (referred to as PHEMA to simplify) and hydrophobic polystyrene (PS) films. To better understand the advantages and disadvantages of chemical crosslinking approaches and the influence of polymer matrices on sensing performance, PtTFPP was physically incorporated into the same PHEMA and PS matrices to compare. Response to dissolved oxygen (DO), leaching of the sensor molecules from their matrices, photostability of the sensors, and response time to DO changes were studied. It was concluded that the chemical crosslinking of the sensor compound 2 in polymer matrices: (i) alleviated the leaching problem of sensor molecules which usually occurred in the physically doped sensing systems and (ii) significantly improved sensors' photostability. The PHEMA matrix was demonstrated to be more suitable for oxygen sensing than PS, because for the same sensor molecule, the oxygen sensitivity in PHEMA film was higher than that in PS and response time to DO change in the PHEMA film was faster than that in PS. It was the first time oxygen sensing films were successfully prepared using biocompatible hydrophilic PHEMA as a matrix, which does not allow leaching of the sensor molecules from the polymer matrix, has a faster response to DO changes than that of PS, and does not present cytotoxicity to human lung adenocarcinoma epithelial cells (A549). It is expected that the new sensor compound 2 and its similar compounds with chemically crosslinking characteristics can be widely applied to generate many interesting oxygen sensing materials for studying biological phenomena.
Instrumental Aspects of Oxygen Sensing: Quantitation and Recalibration of a Biofouled Oxygen Sensor
2017
In vivo oxygen sensing is a critical area of research for medical applications, such as ischemic stroke, but this important topic is not fully understood or resolved. In addition, the best method for calibration of in vivo sensors is as yet undetermined. For all implantable devices, biofouling, the adsorption of biological material to the device surface, is another significant problem with no clear or well-defined solution. One method employed is to apply a protective polymer membrane to the sensor surface in order to minimize the adsorption of biological material. The work described here investigates two polymers applied to a gold electrode for oxygen sensing: polyeugenol (PE) and poly-o-phenylenediamine (PoPD). Polyeugenol, while permeable to oxygen, and unhampering to the overall oxygen sensitivity for the sensor, shows polymer instability, and is therefore not applicable to long-term in vivo sensors. PoPD is shown in these works to be both permeable to oxygen and mechanically st...
Optimisation of a polymer membrane used in optical oxygen sensing
Sensors and Actuators B: Chemical, 2004
A method for detection of viable cells utilises a sensor based on the optical measurement of oxygen consuming by cells. Changes in the oxygen level were measured via quenching of the fluorescence of an oxygen-sensitive fluorophor (Ru(dpp) 3 Cl 2 ). The fluorescence lifetime changing was measured in accord with Stern-Volmer equation, using a phase-shift method. The fluorophor was embedded into a polysulfone membrane that is in contact with the cell medium. The sensitivity of oxygen sensor depends on behaviour of polysulfone membrane. Manufacturing method, type of polysulfone and concentration of fluorophor can also change this behaviour. These parameters were explored to obtain the optimum analytical performance, and the optimum sensitive membrane was chosen for 3 mmol/l concentration of fluorophor, when a linear plot was obtained with R = 0.99987 for a sensitivity of 12.11 ± 0.11 mV/% O 2 (n = 5).