The alignment of LC side‐chain polymers in directing electric fields: theory and practice

The factors that control the alignment of LC side‐chain polymers in directing a.c. and d.c. electric fields are critically reviewed. The principles involved when alignment is attempted by cooling from the melt in the presence of an electric field or by direct application of the field to a material in its liquid‐crystalline (LC) state are outlined, and the difficulties which may be encountered in practice are described and evaluated. An “electrical cleaning” method whereby the low‐frequency conductance losses in a sample may be reduced is described and is applied to LC polymer materials. Experimental dielectric data are presented and analysed for two LC polymers which contain azo‐groups in the side chains.