Synthesis, characterization and phase behaviors of polypeptides bearing biphenyl mesogens and oligo-ethylene-glycol tails

A series of polypeptides bearing biphenyl mesogenic side-chains and oligo-ethylene-glycol (OEG) tails (PPLG n - g -BPOEG m , n = 26 and 63, m = 2, 3, and 7) has been synthesized via a 1,3-dipolar cycloaddition with quantitative grafting density. FTIR results revealed that the polypeptides adopted highly stable α -helix in the temperature range of 25–200 °C. DSC, POM and WAXS analysis revealed that PPLG n - g -BPOEG m ( m ≤ 3) samples with short OEG tail length showed two main phase transitions including crystal to liquid crystalline (smectic C, SmC) phase transition and the melting transition of crystalline E-phase, while PPLG n - g -BPOEG 7 with longer OEG tail length ( m = 7) exhibited the melting transitions without the formation of liquid crystalline phase.