A series of side chain liquid crystalline polymers (SCLCPs) containing triphenylene (Tp) units in the side chains

denoted as PMTS (without spacer) and PMTnS (

n

= 2

3

4

6

which is the number of the methylene units between the main chain and Tp moieties in the side chains)

with different lengths of spacers were synthesized through conventional free radical polymerization. The chemical structures of the monomers were confirmed by

1

H/

13

C-NMR

and the phase behaviors were examined by differential scanning calorimetry (DSC)

polarized optical microscopy (POM) and wide-angle X-ray diffraction (1D and 2D WAXD). The molecular characterization of the polymers was performed with

1

H-NMR

gel permeation chromatography (GPC) and thermogravimetric analysis (TGA). The phase behaviors of the polymers have been investigated by a combination of techniques including DSC

POM

1D and 2D WAXD. The results showed that the length of spacer has significant effects on the LC phase behavior of polymers. For PMTS and PMT2S

they displayed the columnar phase developed by the Tp moieties and the main chain as a whole due to the strong coupling effect of the Tp moieties and the main chain. For the PMT3S

PMT4S and PMT6S

they formed the symmetry hexagonal columnar (Φ

H

) phase owing to the decoupling effect. All of these indicated that the "decoupling effect" or "coupling effect" depended on the length of spacers

leading to the different LC phase formation mechanism.