Electrically sensitive polymers applied electric field

The model of electric field-controlled artificial muscles has been described in 1972 [5], Fragala et al. fabricated an electrically activated artificial muscle system which uses a weakly acidic contractile polymer gel sensitive to pH changes. The pH changes are produced through electrodialysis of a solution. The response of the muscle as a function of pH, solution concentration, compartment size, certain cations, and gel fabrication has been studied. The relative change in length was about 10%, and the tensile force was 1 g/0.0025 cm2 under an applied electric field of 1.8 V and 10 mA/cm2. It took 10 min for the gel to shrink. 

Cerrai and Tricoli examined the polymerisation of anethole by BF Et20 in ethylene chloride under the influence of an electric field. They were able to characterise spectroscopically both the carbocation derived from the monomer at 385 nm (sensitive to the presence of the field as already reported and a catalyst-monomer (or polymer) complex at 333 nm, not affected by the applied field. 

In course of subsequent work Bubeck, Tieke, and Wegner discovered that the action spectrum for photopolymerization of undoped diacetylene multilayers extends into the visible provided some polymer formed in course of previous UV-irradiation is present. Since obviously excitation of the polymer can sensitize the reaction this effect has been termed self-sensitization. Checking the absorption spectrum of the polymer produced via self-sensitization assured that the final product is identical with the product obtained under UV excitation of the monomer. Later work by Braunschweig and Bassler demonstrated, that the effect is not confined to multilayer systems but is also present in partially polymerized single crystalline TS-6, albeit with lower efficiency. Interestingly, the action spectrum of self-sensitization follows the action spectrum for excitation of an electron from the valence band of the polymer backbone to the conduction band rather than the excitonic absorption spectrum of the polymer which is the dominant spectral feature in the visible (see Fig. 21). The quantum yield is independent of the electric field, whereas in a onedimensional system the yield of free carriers, determined by thermal dissociation of optically produced, weakly bound geminate electron-hole pairs, is an linear function of an applied electric field 29.30,32,129) Apparently, the sensitizing action does not... 

Capillary electrophoresis systems are used for chromatographic separation of charged species based on mobility in an applied electric field. UV-visible absorbance and fluorescence detectors are utilized for specific and sensitive quantitation of different analytes. Applications include the determination of inorganic and organic components or additives in plastic formulations, determination of inorganic anions at parts-per-billion levels, and determination of small organic acids in various polymers. 

ELS is a sensitive tool for the study of charge molecules in solution. Most recently we applied this technique to the study of protein-polyelectrolyte com-plexation [38], as shown by the example in Fig. 15.11, which is the mobihty obtained at different pH for RNAse-LBN 66. One notes that the mobihty of the complex starts decreasing around 9.10 as the pH progresses toward phase separation. When pH < 9.10 the measured u values are identical to the mobihty of LBN 66 polymer. The onset of the mobihty change at pH 9.10 can be easily understood as a result of initial protein-polymer complexation by considering the motion of a complex in a electric field. 

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