Correlation of polymer content and electric permittivity

This proves that only the extended tr-electron system of the diacetylene backbone is responsible for the enhanced polarizability. This conclusion is supported by the experimental analysis for three orthogonal directions in TS single crystals shown in Fig. 9.33 [75]. The minor variations for the two orthogonal directions (2) and (3) can be explained by the changes of the lattice parameters. In contrast, the change of the respective lattice parameters with polymer content does not suffice to explain the change of Ae.  

The linear relation between permittivity and polymer content is in principle surprising because there is a distribution of chain lengths of solid state polymerization, differing between induction period and autocatalytic range. The linearity, shown in Fig. 9.34c, reveals that the polarizability of the rr-electron system saturates already at chain lengths below the shortest ones occurring during thermal solid state polymerization. 

The experimental range for is 1.4 to 2.2 derived for different substituted diacetylenes by Gruner-Bauer [72-75], which agrees with the observations of other groups [76-78]. These values compare favourably with the estimate Ae 1.6 obtained for TS by simplified model calculations [75]. For these theoretical estimates the method of Genkin and 

Mednis [79] has been modified by Gnmer-Bauer, extending earlier work for the transparency region [80], 

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