Dual Polymer Cells

Cells with two electrochromic polymers with complementary dyeing characteristics, dual polymer cells, like cells in which FEDOTFSS was combined with polypyrrole gained significant attraction as early as 1997 since besides flexibility they offer potentially high optical contrasts ( 50% transparency) as well as multicolor capabilities and gave rise to an optimistic view of the future of such systems.  

Transition metal ions, electronically coupled to the conjugated backbone, allowed further tuning of the polymer s redox properties, which behaved complementary to FEDOT. A-B-type polymers with EDOT and carbazole structural units turned out to be another class of polymers anodically coloring that can successfully be combined with alkylenedioxythiophenes. -  

Dual cells made from FEDOT and polyaniline as the complementary layer o 331 seem to be less suitable for technical applications since they exhibit a pale yellow bleached state that switches to dark blue. However, a combination with a polyaniline derivative, poly(o-methoxy aniline) a device with high optical contrast of 75% and a transition from fransparent to dark blue was obtained, which exhibited significant degradation in short time. 

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Construction of a dual-polymer electrochromic device (type iii memory device) that has two face-to-face polymer layers in each cell producing 400 (20 x 20) different combinations of absorptions was shown by Sonmez and Sonmez [84], In this study, several examples of this 3x3 pixel dual polymeric electrochromic device composed of red poly(3-alkylthiophene), green poly(2,3-di(thien-3-yl)-5, 7-di(thien-2-yl)thieno[3,4-fc]pyrazine] and blue PEDOT polymers, which switch at different wavelengths, were presented. These distinct absorption states have led to speculation that electrochromic polymers could be used for memory storage devices and computing functionalities. 

Figure 1. Dual polymer electrochromic cell with anodically and cathodically coloring polymers separated by a gel electrode (taken from [409b]).

Saha, M. S., Gullb, A. R, Allen, R.J., and Mukerjee, S. High-performance polymer electrolyte fuel cells with ultralow Pt loading electrodes prepared by dual ion-beam assisted deposition. Electrochimica Acta 2006 51 4680-4692. 

Fig. 37.11. Use of an NO microsensor for detection of the NO release from cultured endothelial cells. The sensor is a dual probe microsensor. The small sensor is a bare Pt UME used to position the sensor in the feedback mode. Onto the larger Pt electrode a polymer was deposited from an acrylic resin containing Ni(4-lV-tetramethyl) pyridyl porphyrin and served as amperometric NO sensor, (a) Schematic of the sensor, (b) optical microphotograph of the sensor surface, (c) Response of the NO sensor to the stimulation of the cells with bradykinin at different distances of the sensor to the surface of the cells. Reprinted with permission from Ref. [104], Copyright 2004, American Chemical Society.

Cotton fibers are single cells composed primarily ( 96%) of the polymer cellulose. In our laboratory (5), cotton fibers were dissolved directly in the solvent DMAC-LiCl. This procedure solubilizes fiber cell wall components directly without prior extraction or derivatization, processes that could lead to degradation of high MW components. MW determinations have been carried out by a size-exclusion chromatography (SEC) system using commercial columns and instrumentation with DMAC-LiCl as the mobile phase. Incorporation of viscometry and refractive index (RI) detectors (6) allowed application of the universal calibration concept (7) to obtain MW distributions (MWDs) based on well-characterized narrow-distribution polystyrene standards (5). The universal calibration concept used by incorporation of dual detectors bypasses the need for cellulose standards. There are no cellulose standards available. Polystyrene standards for a wide range of MWs dissolved readily in DMAC-0.5% LiCl with no activation necessary. 

Chitosan, an important structural component of several fungi cell walls, is a liner p-(l,4)-glucosamine polymer produced by deacetylation of chitin and was reported to be the most active ingredient contained within fungal cell walls [19]. It was convincingly demonstrated that chitosan had a potential dual role inducing... 

A large problem in polymer electrolyte membrane fuel cell operation is a possible partial condensation of water vapor when temperature gradients are present in the fuel cell and a dual-phase water system develops. 

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