We have developed a polar polymer film with a fixed polar
assembly
based on the phosphine oxide group. A polymerizable columnar liquid
crystal with a polar triphenylphosphine oxide core was designed and
synthesized. The in situ photopolymerization of the columnar liquid
crystal under electric fields leads to fixation of a one-dimensional
polar alignment of the phosphine oxide group. Fixation of the polarity
of the cross-linked film was confirmed based on the results of second-harmonic
generation measurements. In contrast, the polarity of the non-cross-linked
triphenylphosphine oxide-based columnar liquid crystals was switchable
under external electric fields. Moreover, it was not maintained after
the removal of the electric fields. These findings have significant
implications for potential applications in piezo-responsive devices
and contribute to a broader understanding of polar liquid crystals
and their prospective uses.