Controlling The Phase Behavior And Phase Structure Of ILCPs Through Tuning The Length Of The Alkane Chains

The fabrication of ordered structure is very important for the applications ofionic liquid crystal polymers (ILCPs). In this paper, we focused on the design，synthesis, the phase behavior and the supra-molecular structures of a series of ILCPscontained imidazolium based on the Mesogen-Jacketed Liquid Crystalline Polymers(MJLCPs).First, we designed and synthesized a series of novel ionic monomers containedimidazolium,2,5-bis{[6-(4-butoxy-4′-imidazolium phenyl) k-alkyl] oxy carbonyl}styrene bis (fluoroborate) salts (denoted as Mk-6BF4, k represents the number of carbonin the alkyl tails and k=4,8,12,16) and2,5-bis{[m-(4-butoxy-4′-imidazolium phenyl)m-alkyl] oxy carbonyl} styrene bis (fluoroborate) salts (denoted as M4-m BF4, mrepresents the number of carbon in the alkyl spacers and m=2,4,6,10). Thecorresponding polymers Pk-6BF4and P4-m BF4were abtained via radicalpolymerization. The chemical structures of the monomers and the correspondingpolymers were confirmed by1H NMR,13C NMR and fourier transform infraredspectroscopy (FTIR). And the thermal stability has been investigated bythermogravimetric analysis (TGA). It has been demonstrated that these PILCs hadexcellent thermal stability.Combined differential scanning calorimetry (DSC), polarized light microscopy(PLM), small-angle X-ray scattering (SAXS), one-dimensional wide-angle X-raydiffraction (1D WAXD) and two-dimensional wide-angle X-ray diffraction (2DWAXD), Pk-6BF4(k=4,8,12,16) were found to form SmA phase, and thed-spacing of the layer was increasing with increasing of alkyl tail length. What’s more,the degree of the order of the phase structure was inproved.In another system, we find that the ordered structure of this ILCPs P4-m BF4(m=2,4,6,10) can transfer from smecticA phase (SmA) to hexagonal columnar (ΦH)phase with the increase of spacer. Furthermore, these results were confirmed byreconstructed relative electron density map using fast fourier transform algorithm(FFT). It was evident that the alkyl spacer played an important role in the constructingof ordered structure and offered a new method to fabricate different ordered structureof ILCPs.