Spacer groups polymers without flexible

Polymers without flexible spacer groups. The DSC curves of t he polymer 3 indicated the existence of a liquid crystalline glassy state at room temperature. The polymer was found to be smectic. Two melting peaks were observed in the temperature range between 300 and 310 deg. C. These peaks are not as easily observed as in the case of the polymers discussed above, since the decomposition takes place in the same temperature range. The occurrence of exothermic peaks on cooling nevertheless indicates that reversible melting and crystallization processes take place. 

Figure 1. Structures of liquid crystalline polymers (LCPs) (A) rigid rod LCP [25, 65] (B) main chain LCP with flexible spacer [26] (C) side group LCP with flexible spacer [27] (D) combined main/side group LCP [28] (E) side group LCP without flexible spacer or mesogen jacketed LCP [29], (F) well-defined three-arm star [30] (G) LC dendrimer [33].

In this paper three kinds of polymers will be considered (polymers 1, 2 and 3) in which mesogenic groups are either attached to the flexible backbone via flexible spacer groups (polymers 1 and 2) or directly without spacer groups. The polymers studied are shown in table 1. 

In polymers 1 and 6, the mesogenic group is separated from the main chain by a flexible polymethylene spacer. For these polymers, the optical anisotropy and the Kerr constant are lower by one order of magnitude than for polymers with a similar structure of the mesogenic side chain but without a flexible unit. 

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