Use Of Polymer Films Research Articles

Polymers in biosensors - a review

Biosensors offer enormous potential to quantitatively estimate a wide range of analytes in health care, chemical process industries, food industries and environmental monitoring. Polymers play an important role starting from the manufacturing of the electrodes to the immobilization process of the biomaterials. This review concentrates on the use of polymer films in the development of advanced biosensors. The functions of polymer film, e.g. removal of interference, immobilization of biocomponent etc. and deposition of polymer films on the sensor surface are discussed thoroughly.

The Development of Solid Spectral Filters for the Regulation of Plant Growth

ABSTRACTPhthalocyanine derivatives have been prepared and incorporated into polymer films for use as spectral filters for the modification of plant growth. The unusual absorption characteristics of phthalocyanines, notably the narrow absorption band in the visible region of the electromagnetic spectrum, allows the selective filtering of wavelengths necessary for excitation of either of the two isomeric phytochrome species. The resulting change in the photostationary state for the phytochrome is shown to have a marked effect on the growth characteristics of both chrysanthemums and antirrhinums. Chrysanthemums (short‐day plants) grown under a far‐red‐absorbing film showed a reduction in height (∼14%) and internodal length compared to those grown under a red‐absorbing film or a control with no absorption in the visible part of the spectrum; both leaf number and time to flowering were not affected by the presence of the spectral filter. For antirrhinums (long‐day plants) both a reduction in height and a substantial increase in leaf area (70%) of the plants grown under the far‐red‐absorbing film were observed, although flowering was delayed. The potential of these filters as replacements for chemical plant growth regulators is discussed.

Volatile Compounds for Control of Botrytis on Strawberry: Duration of Treatment and Use of Polymer Film

A number of natural volatile compounds exhibit promise as postharvest fumigants for control of Botrytis on strawberry fruit. Because some of compounds may cause apparent phytotoxic responses by the fruit, short duration treatment is desirable. The compounds have been evaluated in single fruit bioassays with passively established modified atmospheres using a polymer film. The compound source was removed after 3 hours, 1, 3, or 7 days, or remained in the containers for the 10 day duration of the study. At levels which inhibited Botrytis in closed containers without film, E-2-hexenal was effective with a 1-day treatment, diethyl acetal was increasingly effective as treatment period increased, and 2-nonanone and methyl salicylate were not effective with continuous treatment. The levels of both the source compound and its metabolites were different using the film than without it. The film, used to allow gas diffusion and exchange with the surrounding environment, may allow diffusion of the volatile compounds and their metabolites. Thus, successful use of the compounds in modified atmosphere storage may require knowledge of their diffusion through the films to establish the appropriate levels for effective fumigation of the fruit and avoid adverse quality effects.

Use of polymer films in amperometric biosensors

AbstractDifferent types of polymeric films implemented in various capacities in amperometric biosensor design are reviewed. Conducting and nonconductinzg polymer films and composite films are considered. Methods of film fabrication such as solvent casting, electropolymerization, and adsorption are presented. Film function, including prevention of interference and fouling problems, immobilization of the enzyme or active biocomponent, extension of linear range, or to address biocompatibility problems are described. The use of polymeric films as a medium to incorporate mediators, while an important function, is too vast for review here. The applications of polymer film‐modified biosensors for selected analytical determinations are also presented. This review focuses upon the use of polymer films in amperometric biosensors and emphasizes innovative biosensor designs and unique applications, and omits traditional free‐standing films unless they are coupled with new types of polymer films or used innovatively.

Mass transfer from and through packaging materials

AbstractThe use of polymer films for food packaging requires a knowledge of their transport properties under varying conditions. The permeability to gases and water vapour of the packaging films at the specific conditions of use, i.e. temperature, relative humidity and pressure gradient, are needed for selecting the optimum packaging system to ensure the required shelf‐life of the packed product. Migration from, and absorption by, plastic films also play an important role in their selection.The 02 and CO2 permeabilities of three plastic films at four different temperatures were evaluated and shown to follow the Arrhenius relationship in the range tested. The effects of four thicknesses of one film on its permeability are also reported.Three methods to evaluate migration from polymeric films were compared using different weight/volume ratios. The extraction method recommended by the FDA, using n‐hexane in a stirred flask, was found to be best.The shelf‐life of Matzoth (Jewish Passover bread) packed in polyethylene (stored at 25°C) was found to be longer than the shelf‐life of those packed in the higher barrier PVDC/PE. This was apparently due to the absorption of undesirable oxidation compounds, given off from the Matzoth by the PE, which were not absorbed at detectable levels by the PVDC/PE.

Reactive sputter sectioning: A tool for polymer film analysis

Reactive sputter etching has been used to create thinned ‘‘sections’’ of polymer films for use in microstructural analysis. This paper emphasizes the features of the sputter etching process which must be controlled to permit efficient sectioning without the introduction of artifacts, such as microstructural changes induced by heating and surface texture which might obscure subsequent analysis. Sample mounting techniques which allow oxygen sputter etching rates of 20 μm/h without heating of the film above 50 °C and simple electrode surface design rules which allow etching for long periods with very low levels of surface texturing are described. The minimum oxygen flow rates which must be supplied to prevent a depletion of the oxygen reactant and a concomitant reduction in the etch rate are noted. The utility of the technique is demonstrated with results from a study of the microstructure of a cast polypropylene film as a function of depth through the film.

Photolysis of polymers using the medium pressure mercury lamp: Part 3—Photolysis of poly(2-ethylhexyl acrylate), alone and in presence of benzoin

The photolysis of poly(2-ethylhexyl acrylate) (P2EHA) has been studied using techniques recently devised for the use of polymer films on metal supports. Condensable volatile products have been identified and measured quantitatively for various times of irradiation and the development of crosslinking has been followed by sorption measurements using a radioactive solvent and a non-solvent medium. The effect of a low concentration of benzoin on the photolysis reaction has also been examined. The photolysis products are as expected from the general scheme of polyacrylate photolysis given by Fox et al., comprising carbon dioxide, alkane, alkene, alcohol, aldehyde and formate. No additional materials have been observed. Crosslinking occurs much more slowly in the case of P2EHA than for PMA photolysis: this is attributed to the effect of the bulky branched side group in hindering macroradical combination. A greater proportion of short chain fragments is observed. Benzoin retards crosslinking and the production of volatiles.

Gas permeability of polymer films for use in membrane oxygenators.

Gas permeability of polymer films for use in membrane oxygenators.

Use of polymer films in local repair work on reservoirs

Polymer films can be used successfully as local sealing measures on reservoirs and dams, especially under unfavorable soil conditions (slumping, piping, severely seeping loose soils, etc.). These measures can be provided when designing and used after construction to eliminate the aftereffects of seepage and settling.