Multiple Effects Tailoring the Self-organization Behaviors of Triphenylene Side-chain Liquid Crystalline Polymers <Emphasis Type="Italic">via</Emphasis> Changing the Spacer Length

Long-alkyl tail triphenylene (TP) side-chain liquid crystalline polymers (SCLCPs) with different spacer length (P-m-TP,m =2,3,4,6,8,which is the number of carbon atom in the flexible alkyl spacers) have been successfully synthesized via free radical polymerization.The differential scanning calorimetry (DSC),polarized light microscopy (POM),ultraviolet-visible spectroscopy (UV-Vis),wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) measurements were performed to investigate the influence of multiple effects on the self-organization behaviors of P-m-TP,including steric effect,decoupling effect and π-π stacking effect.The experimental results revealed that P-m-TP (m =2,3,4) formed the columnar phase which was developed by the TP moieties and the main chain as a whole,suggesting that the side-chains had strong steric effect even though the number of spacer length (m)exceeded 4.In addition,the clearing points (Tis) of the polymers were above 300 ℃.When m =6 and 8,the polymers displayed hexagonal columnar phase and exhibited the low Tis (91 and 80 ℃ respectively),originating from the self-assembly of triphenylene due to the decoupling effect and π-π stacking effect.This work offers a viable and inspiring pathway to control the phase transition temperature and phase structure of TP SCLCPs via simply tailoring the spacer length and increasing the alkyl tail length of TP.