Triphenylmethane leucocyanide

Fig. 18. Photostimulated dilation and contraction of polyacrylamide gel containing 1.9 mole % pendant triphenylmethane leucocyanide groups with light of wavelength longer than 270 nm at 25 °C [43]. Wo is the weight before photoirradiation...

Fig. 19a, b. Photostimulated (a) color change and (b) dimension change of polyaotylamide gel containing 1.9 mole % triphenylmethane leucocyanide groups in water [43]. Ig is the initial diameter of the disk-shaped gel befOTe photoirradiation... 

The polyacrylamide gel described abobe is the first example showing a reversible deformation of more than 100%. The effect is purely photochemical and reversible. However, this gel has a serious disadvatage in that the response time is slow. To improve this point the effect of electric field on the gel deformation was examined [44]. A rod-shaped polyacrylamide gel containing triphenylmethane leucocyanide groups (25 mm in length and 2 mm in section diameter) was prepared in a capillary tube. The gel rod was inserted between two parallel platinum electrodes in a small... 

Fig. 20. Photostimulated vibrational motion of a rod shaped polyacrylamide gel having 3.1 mol% triphenylmethane leucocyanide groups under an alternating electric field ( + 0.8 v/cm, 0.5 Hz) in water in the preseiK of4x lO MNaCl...

Figure 4. Photostimulated size and shape changes of polyacrylamide gels having triphenylmethane leucocyanide groups (3.1 mole %) (A) before photoirradiation, (B) the whole gel being irradiated with ultraviolet light, (C)before photoirradiation, (D) upper side of the rod shaped gel being irradiated.

X 19 X 15 mm) with two parallel platinum electrodes(26). The rod-shaped gel was placed parallel to the electrodes to avoid the contact of the gels with the electrodes. The acrylamide gels containing triphenylmethane leucocyanide groups(25 mm in length and 2 mm in section diameter) were prepared in capillary tubes by the same method as described in the previous section. 

Figure 6. Photostimulated bending motion of a rod shaped acrylamide gel (25 mm in length and 2 mm in section diameter) having 3.1 mole% triphenylmethane leucocyanide groups in an electric field (10 V/cm) in water (A) before photoirradiation, (B)under ultraviolet irradiation, (C) under ultraviolet irradiation, polarity of the electric field being opposite to that in (B).

Large, real effects, on the other hand, were observed with hydrogels. A typical result is presented in Fig. 5.12, which shows how a polyacrylamide gel containing 1.9 mol% triphenylmethane leucocyanide swells upon irradiation with UV light at 25 °C [49]. The swelling is correlated to a 18-fold increase in the relative weight. 

Fig. 5.12 Photomechanical effects. UV-light-stimulated dilatation of a polyacrylamide gel containing pendant triphenylmethane leucocyanide groups (1.9 mol%) at 25 °C. Adapted from Irie et al. [49] with permission from the American Chemical Society.

Kurihara S, Ueno Y, Nonaka T. Preparation of poly(vinyl alcohol)-graft-N-isopropylacrylamide binary membranes with triphenylmethane leucocyanide and permeation of solutes through membranes. J Appl Polym Sci 1998 67 1931-1937. 

Polyacrylamide gels containing a small amount of triphenylmethane leucohydroxide or leucocyanide groups 21) were prepared by free radical copolymerization of di(iV,iV-dimethylaniline)-4-vinylphenylmethane leucohydroxide 12, X=OH, R=... 

A concentration cell has been described which is based upon the ionic photodissociation of the leucocyanides of the triphenylmethane dyes crystal violet or malachite green in acetonitrile or alcohol, as in reaction (4).28 This reaction is... 

Radiochromic film dosimeters. Many polymer-based film dosimeters have been developed containing various types of dyes, whose color or depth of color changes during irradiation. Certain leucocyanides or leucomethoxides of triphenylmethane dyes are widely applied in the dose range of 10 -10 Gy (McLaughlin 1974,1977, 1985, ISO/ASTM 51275). 

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