Influence of main-chain and molecular weight on the phase behaviors of side-chain liquid crystalline polymers without the spacer

Abstract

A series of end-on side-chain liquid crystalline polymers (SCLCPs) based on a biphenyl mesogen, poly(4,4 0 -alkoxybiphenyl acrylate) (PBiA-m, m = 1, 4, 6, 10, 18), were successfully synthesized by free radical polymerization or reversible addition fragmentation chain transfer (RAFT) polymerization. The chemical structures of the monomers were confirmed by 1 H NMR and mass spectrometry. The phase structures and transition behaviors were studied using DSC, POM and 1D WAXD. The experimental results found that PBiA-m showed the bilayer smectic phase and a higher clearing point (T i ) compared with poly(4,4 0 -alkoxybiphenyl methacrylate) (PBiMA-m). In addition, poly(4,4 0 -hexyloxybiphenyl methacrylate) (PBiMA-6) and poly(4,4 0 -hexyloxybiphenyl acrylate) (PBiA-6) with different molecular weights (M n ) and low molecular weight distributions have been successfully synthesized via the RAFT polymerization. The results indicated that all the polymers exhibited a bilayer smectic phase and T i increased as the M n of PBiMA-6 and PBiA-6 increased. Moreover, PBiA-6 had a higher T i compared with PBiMA-6 with a similar M n value. All the results suggested that the main-chain (acrylate and methacrylate) and M n had a great influence on the properties of SCLCPs without the spacer.

Synthesis and characterization of chiral smectic side-chain liquid crystalline elastomers containing nematic and chiral mesogens

“…6,7 Polymerization of the flexible backbone and different liquid crystalline mesogens with varying orientational ordering endows the LCEs with a lot of unusual traits. [8][9][10] The interplay between the liquid crystalline orders and the polymer network structures makes LCEs applicable for many practical uses, such as micromechanical systems, propulsion systems, optical materials, and electronic devices. [11][12][13][14][15][16][17][18][19] Chiral smectic LCEs were one of the focuses in the LCE research field.…”