Synthesis and characterization of chiral liquid crystal polymers containing donor–acceptor group

A series of new chiral side-chain liquid crystalline polymers with electron donor–acceptor action were prepared containing chiral monomer with donor group and nematic LC monomer with acceptor group. All polymers were synthesized by graft polymerization using polymethylhydrosiloxane as backbone. The mesomorphic properties were investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), thermogravimetric analyses (TGA), and X-ray diffraction measurements (XRD). The chemical structures of monomers and polymers were confirmed by Fourier transform infrared (FTIR), proton nuclear magnetic resonance spectra (¹H NMR and ¹³CNMR). M₁ did not show liquid crystalline phase and M₂ turned out nematic phase on heating and cooling cycle. Polymers P₂–P₇ were cholesteric phase. Cholesteric phase and low glass temperature liquid crystalline polymers have been obtained, which offered the possibility of application. Experimental results demonstrated that the glass-transition temperatures rose and isotropization temperatures decreased and the ranges of the mesophase temperature reduced with increasing the content of chiral agent. All of the obtained polymers showed high thermal stability.